The Theory of Evolution and Its Impact

The Theory of Evolution and Its Impact . Aldo Fasolo Editor The Theory of Evolution and Its Impact Editor Aldo F...

Author: Aldo Fasolo

75 downloads 1592 Views 3MB Size Report

This content was uploaded by our users and we assume good faith they have the permission to share this book. If you own the copyright to this book and it is wrongfully on our website, we offer a simple DMCA procedure to remove your content from our site. Start by pressing the button below!
Report copyright / DMCA form

DOWNLOAD PDF

The Theory of Evolution and Its Impact

.

Aldo Fasolo Editor

The Theory of Evolution and Its Impact

Editor Aldo Fasolo Dipartimento di Biologia Animale e dell’Uomo Universita` di Torino Via Accademia Albertina 13 I-10124 Torino Italy [email protected]

The publication of this book has been made possible by the financial support of the Accademia delle Scienze di Torino. ISBN 978-88-470-1973-7 e-ISBN 978-88-470-1974-4 DOI 10.1007/978-88-470-1974-4 Springer Milan Dordrecht Heidelberg London New York Library of Congress Control Number: 2011927742 # Springer-Verlag Italia 2012 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable to prosecution under the German Copyright Law. The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover illustration: Nanni Valentini, Cratere, 1978-80. Private collection. Printed on acid-free paper Springer is part of Springer ScienceþBusiness Media (www.springer.com)

Contents

Introduction: The Sand Walk (on the Darwin’s Steps) . . . . . . . . . . . . . . . . . . . . . 1 Aldo Fasolo Idola Tribus: Lamarck, Politics and Religion in the Early Nineteenth Century . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 Pietro Corsi Darwinism Past and Present: Is It Past Its “Sell-by” Date? . . . . . . . . . . . . . . . 41 Michael Ruse Evolutionary Theory and Philosophical Darwinism . . . . . . . . . . . . . . . . . . . . . . . . 53 Paolo Casini Struggle for Existence: Selection, Retention and Extinction of a Metaphor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 69 Peter Weingart The Theory of Evolution and Cultural Anthropology . . . . . . . . . . . . . . . . . . . . . 83 Henrika Kuklick The Concept of Evolution in Linguistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103 Manfred Bierwisch Theory of Evolution and Genetics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 119 Alberto Piazza Genes, Evolution and the Development of the Embryo . . . . . . . . . . . . . . . . . . . 131 Giuseppina Barsacchi

v

vi

Contents

Evolutionary Mechanisms and Neural Adaptation: Selective Versus Constructive Strategies in the Development and Plasticity of the Nervous System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 159 Ferdinando Rossi Is the Human Brain Unique? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 175 Gerhard Roth Aristotle and the Chicken: Animacy and the Origins of Beliefs . . . . . . . . . . 189 Giorgio Vallortigara Evolution: Remarks on the History of a Concept Adopted by Darwin . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 201 Volker Gerhardt An Evolving Research Programme: The Structure of Evolutionary Theory from a Lakatosian Perspective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211 Telmo Pievani

.

Introduction: The Sand Walk (on the Darwin’s Steps) Aldo Fasolo

Abstract To understand the status of Theory of Evolution, highly multidisciplinary approaches are needed. Thus, the book moves from the historical and philosophical roots, to follow a long and winding road, passing from anthropology, to linguistics, genetics, developmental biology, neuroscience, cognitive studies, to find a final lap on today theories. The inescapable conclusion, quoting the contribution of the philosopher Michael Ruse, is “that in fifty years or a hundred years we will still have the theory of the Origin around. Great, precisely because it does not stand still, but remakes itself and grows and changes by virtue of the fact that it gives such a terrific foundation. Is Darwinism past its sell-by date? Not by a long chalk yet!”

Year 2009 celebrated the triumph of Darwin as global superstar, spinning from the pop icon to the actual understanding to what make him a great innovator, able to give a turn to the whole modern culture. After such a deluge of books, conferences, reviews, gadgets, what is today our vision on theory of Evolution and its Impact? This was exactly the goal of an inter-academy meeting held in Torino (May 27–29, 2010) involving the Accademia delle Scienze di Torino, the Accademia Nazionale dei Lincei and the Berlin-Brandenburgische Akademie der Wissenschaften. The preliminary question was obviously if we needed another meeting on such a topic. In the commentary about a book recently published on the first 150 years since Darwin [1], reporting the dramatic expansion of the applications of evolutionary science in recent years and the wages in terms of confirmations and extensions, David P. Mindell closes saying: “Does all this activity mean evolution has lost its ability to excite fear and opposition?” Not yet. As the root for natural explanations of human origins . . . and ultimate impetus for human moral behaviour and values, evolution remains the disturbing discovery.

A. Fasolo (*) Department of Animal and Human Biology, University of Turin, Turin, Italy e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_1, # Springer-Verlag Italia 2012

1

2

A. Fasolo

This is even more relevant, if we step from biological sciences to humanities. Accordingly, the goal of the meeting was to achieve a broad analysis of the impact, pinpointing on a few specific, but paradigmatic topics. Even the place was well tempered, since Torino was in Italy one the main diffusion spot for Darwinian thought and work, both from the academic and editorial point of view. The present book collects essentially contributions (except for Rossi’ and Pievani’s ones) from the meeting, mixing styles, arguments, subjects. This kind of inter-disciplinary approach may appear erratic, but it conveys flashes of light on the changing scenarios where the theory of evolution is moving. It is on line with the idea to reopen the file of the Two Cultures, looking at shared problems, which are not really the Third Culture invoked by Charles Percy Snow half a century ago, but they can foster it, at least in such a pivotal domain as evolution.

1 Roots and Buds of Evolutionary Theory In history of science, for instance, notwithstanding a few crucial contributions, the intellectual credits of pre-darwinian authors remain rather bad known. “The almost total lack of interest for the state of affairs in the publishing industry of the period under consideration, and the total lack of interest for what books, dictionaries, encyclopaedias actually said, made us blind to major debates of great significance for the history of the life sciences at European level during the early decades of the nineteenth century. Thus the reconstruction of the ways in which Lamarck was read, admired, criticized or denounced might be considered a mile stone of the modern reappraisal of history of evolutionary thought.” Thus Pietro Corsi is crunching the cultural background before and around Darwin, focussing on the set of easy assumptions concerning the place and reputation of Lamarck within the French natural history community of the early decades of the nineteenth century. Such visions acted as true Idola tribus, preventing research and limiting in considerable ways our understanding of the complex intellectual, social and political dynamics of contemporary natural history practices and publishing. In Pietro Corsi’s views, such absence or paucity of interest for made us blind to major debates of great significance for the history of the life sciences at European level during the early decades of the nineteenth century. Accordingly the ways in which Lamarck was read, admired, criticized or denounced might be considered a mile stone of the modern reappraisal of history of evolutionary thought. Even for philosophy it is not true that les jeux sont faits. Wittgenstein famously remarked in [16], “Darwin’s theory has no more relevance for philosophy than any other hypothesis in natural science.” Yet today we are witnessing a major revival of interest in applying evolutionary approaches to philosophical problems, as Michael Ruse accomplished recently with the Philosophy after Darwin [13], an anthology of essential writings covering the most influential ideas about the philosophical implications of Darwinism, from the publication of On the Origin of Species to

Introduction: The Sand Walk (on the Darwin’s Steps)

3

today’s cutting-edge research. Along this same red line, Ruse argues that “work being done today on evolution and philosophy as part of a broader cultural movement. In some very deep sense, it is part of a movement to see human beings in a naturalistic fashion, this being set against more traditional attempts to locate humans in a religious, a spiritual, a non-naturalistic world. One aim, as you might already have guessed, will be to show that the story is not quite as straightforward as one might have expected.” Always on philosophy side, Paolo Casini notes that when John Dewey, in his essay The Influence of Darwinism on Philosophy (1909), remarked “The exact bearings upon philosophy of the new logical outlook are, of course, as yet, uncertain and inchoate. We live in the twilight of intellectual transition”. Nowadays four decades of controversy concerning evolution had elapsed, and Darwin’s Darwinism was eventually accepted, The transition towards evolutionary logic, according to Dewey’s subtle analysis, expelled from biology, and from philosophy as well, all ideal archetypes, the concepts of design and finality, and destroyed the philosophic idol of eidoςτΘ (o species). If we challenge the historical roots of evolutionary theory (as the) with its present day bearings, what remains of emotional ideas like, The Nature, red in tooth and claw? Peter Weingart notes that the metaphor “struggle for existence” takes its origins in everyday language but it was given a specific meaning in the context of evolutionary theory. Subsequently, the metaphor was transferred back into everyday use but had also a tremendous impact on the historical and social sciences. Darwin’s metaphor is one of the most famous cases of this type of metaphor transfer into the sciences and back. Accordingly the usages of the metaphor appear really wide and loose, but nonetheless they had their time. A search for occurrence of such a phrase in titles and/or abstracts of documents in both the SSCI and SCI databases revealed only 21 entries for the period 1973–1999. Evidently it is justified to say that the struggle for existence as a metaphor has not survived the struggle for use and attention.

2 The Mankind Affair Mankind evolutionary history can be tackled in several ways, employing tools from disparate disciplinary fields as cultural anthropology, linguistics, to-date molecular genetics. In a fascinating approach, Henrika Kuklick explores the dialectics and the somewhat contradictory exchanges between Darwinian theory and the new born social anthropology: Anthropological fieldwork framed by a Darwinian biographical approach proved extremely important in changing the discipline, (perhaps paradoxically) leading to a thorough separation of cultural from biological anthropology. . . . Not until the 1980s would evolutionary approaches to the analysis of culture that were advertised as authentically Darwinian seem respectable to more than a distinct minority of socio-cultural anthropologists, but that is a

4

A. Fasolo development that may be most significant as evidence of the rise of conceptual pluralism in anthropology.

A key-corner between biology and society is the language. Manfred Bierwisch draws an elegant and challenging reflection on such a conceptual and experimental labyrinth, where we ignore how many (or if any) are the exits. At a first glance, we are relying on some necessary analogies. Human language history can indeed be logically explained by an evolutionary theory, but its principles are essentially different from those that govern the development of biological species. Then the question is as to whether we have identified a principle of evolution that is universally applicable to the historical development of language and more broadly to sociocultural structures. Favoring the supposition of a fundamental role assigned to language as a basis and ingredient of veritably every sociocultural institution enabling the capacity for unlimited expression, bounding language symbols to agreed convention, Bierwisch notes that there are nonetheless grounds for reservation stemming from two considerations, the domain-specificity of the language faculty and the intentionality of social behavior, including the creativity of language use. The compelling close is that “The faculty of language is the prerequisite of human history, but it does not determine its course.” The theme of the evolution of the language immediately calls us to the extraordinary researches on the genetics of ancient human populations, where pioneering, monumental studies were performed by Luca Luigi Cavalli Sforza, Paolo Menozzi and Alberto Piazza. In the present book, Alberto Piazza is arguing on the role of natural selection, a major factor in Darwinian evolution which is elusive and difficult to dissect, especially when the case of human evolution is dealt with. In August 1858, Charles Robert Darwin and Alfred Russel Wallace presenting to the Linnean Society of London their independent discovery of the theory of natural selection, suddenly and altered our understanding of life on Earth. He is focusing his attention on five major advances of genetics on the analysis of human evolution, and especially on the comparisons between human and chimpanzee genomes and on the very recently published DNA draft sequence of the Neanderthal genome. The very questions for modern humans are: • To which extent has natural selection influenced, at the scale of the entire genome, the degree of population differentiation? • Which type of genetic variants have been preferentially targeted by selection? • Genes and gene variants under strong selective pressures can highlight regions of the genome explaining the current population phenotypic variation? The final challenge is methodological: how can we evaluate the relevance of the sexual selection in humans, starting from the many conjectures and working hypotheses put forward by Darwin, which are very plausible for animals, but very difficult to test for humans, especially in modern times when cultural factors on sexual selection may completely shadow biological pressures.


5

3 Development, a Persistent Problem of Evolutionary Theory If the powerful genetics is sitting in the core of modern evolutionary theory, a blow of new ideas comes from its theoretical belt, as Evolutionary Developmental Biology (Evo-Devo). Thus Giuseppina Barsacchi analyzes the relationships between the processes of individual development and the phenotypic changes of the organism during evolution. Methodological advances such as gene cloning, gene expression screening and visualization of gene activity in embryonic tissues facilitated the emergence of a major theme of the current Evo-Devo research, the evolutionary developmental genetics program. Its foundational achievement was the discovery of extensive similarities in developmental regulatory genes and gene networks among distantly related species. The program concentrates on the evolution of genetic tool-kits and signaling pathways and on the regulatory logic that underlies organism development. Mapping the expression pattern of gene networks and signaling pathways and analyzing their correlation with the constructional features of body architecture, provides information on their possible role in phenotypic evolution. Major morphological transitions in evolution are presently recognized to be accommodated by a few key developmental genetic changes (part of a “developmental reprogramming”) and “case studies” in snakes, ducks, bats, dolphins, insects, and finches, providing valuable insights into principles of evolutionary change, are presented. On the other hand, the molecular changes are rooted in an otherwise conserved developmental genetics tool-kit (e.g., the Hox genes for anterior-posterior patterning, the network for eye formation etc.) that substantiates the “deep homology” underlying diversity of forms. On this ground, the relationship of the deep homology of genes working through development with classic morphological homology is in the Evo-Devo field of exploration. How environmental agents can instruct changes in development, for example altering gene expression – in broad sense searching for a link between proximate causes of development and natural selection-, falls also in the perspectives of newly growing and exciting knowledge, where Evo-Devo integrates with Ecology. The problems are many and very interwoven, as Alessandro Minelli remarks: “a real Evo-Devo biology is now growing in extent and importance, but integration between the two disciplinary components is still basically fought on the battlefield, case by case” ([9], p.118). The case is for instance the principle of “developmental inertia”, raised by Minelli himself, like the arguments about regeneration, developmental pathways, epigenetics, multiplicity of centers of local development dynamics as opposed to global control, and so on. . . Summing up, future work may further give reason for the Charles Darwin’s appraisal of the importance of Embryology for Evolution.

4 Brain Evolution and Plasticity Overcoming the traditional dichotomy opposing neural selectionism to constructivism is the goal of Ferdinando Rossi. In an extreme synthesis, Rossi is arguing in a syncretistic fashion, along the following lines of reasoning. The correct function

6

A. Fasolo

of the nervous system requires complex neural networks bearing precise connections. In principle, the high structural specificity of neural circuits could be achieved by genetically-determined processes, selected and refined during evolution. Highly conserved gene networks regulate some crucial steps of neural development, such as the regionalization of the neural tube and the initial phases of neurogenesis and synaptogenesis. A totally hardwired nervous system may meet the requirements of adaptation and natural selection at the population level, whereas it would be fully inadequate to allow individual organisms to cope with rapid changes of environmental conditions. Neural adaptation to external constraints can be partly achieved by introducing selective mechanisms in neural development. Accordingly, neurons are generated in excess and then partially eliminated to match the actual extension of innervation territories. Such mechanisms, however, are restricted to a set of potentialities, which must be predetermined in the ontogenetic program. On the other hand, constructive mechanisms, in which external stimuli directly influence structural modifications of neural circuits to produce adaptive responses, may allow individual organisms to cope with a wide variety of unprecedented situations. Thus, in the last ontogenetic period as well as in the adult, when the organism actively interacts with the external milieu, experience exerts a strong growth-promoting effect on neural circuits and connections inducing the emergence of specific functional properties. By this mechanism, which requires strict inhibitory control to prevent aberrant growth and dysfunction, the nervous system exploits external stimuli to create adaptive responses to unexpected situations. Such syncretism represents a good way to handle the enormous wealth of data on brain development recently acquired. Nevertheless this approach raises some reflections on tricky concepts such as evolvability [7,11] and exploratory properties in complex systems, namely in neural tissues. Evolvability is an organism’s capacity to generate heritable phenotypic variation. Metazoan evolution is marked by great morphological and physiological diversification, although the core genetic, cell biological, and developmental processes are largely conserved. Metazoan diversification has entailed the evolution of various regulatory processes controlling the time, place, and conditions of use of the conserved core processes. These regulatory processes, and certain of the core processes, have special properties relevant to evolutionary change, reducing the interdependence of components and conferring robustness and flexibility on processes during embryonic development and in adult physiology. Even more ambitiously, we can ask: how our brain evolved? In a masterly way, Gerhard Roth shows that the human brain is not unique in terms of general structure, since it exhibits the basic pattern typical of mammals and more specific of primates. In addition, humans do not have the largest brain either in absolute or in relative terms, although they possess a brain that is seven to eight times larger than expected from general mammalian brain allometry (defined as the study of the change in proportion of various parts of an organism as a consequence of growth). Through an elegant analysis of many other quantitative data, Roth concludes that the greatest differences between humans and all other mammals/consist in (1) a


7

strongly increased growth period of the human brain exposing it to a much higher degree to education, and (2) the presence of the Broca speech area which is a necessary prerequisite of syntactical language. While these two traits appear to be minor steps in human biological evolution, they had enormous consequences for human culture.

5 Old/New Concepts One major methodological and pragmatic problem is an old and persistent one: what is the meaning of similarities, in genetics as in anatomy or in developmental processes? Three old/new friends may help to understand the nature of similarities and their bias. Among new or renewed conceptual tools, one emerging clue is homoplasy [14]. Homoplasy is the independent acquisition of the same trait in unrelated lineages. Parallelism/convergence homoplasy occurs when the same trait is present in two lineages that lack a recent common ancestor. Reversal homoplasy occurs when a trait is present in an ancestor but not its immediate descendants; but appears later in a subsequent descendant. Understanding the diversification of phenotypes through time has been the focus of evolutionary biology for 150 years. If, contrary to expectations, similarity evolves in unrelated taxa, researchers are guided to uncover the genetic and developmental mechanisms responsible. Similar phenotypes may be retained from common ancestry (homology), but a phylogenetic context may instead reveal that they are independently derived, due to convergence or parallel evolution, or less likely, that they experienced reversal. Such examples of homoplasy present opportunities to discover the foundations of morphological traits. A common underlying mechanism may exist, and components may have been redeployed in a way that produces the “same” phenotype. New, robust phylogenetic hypotheses and molecular, genomic, and developmental techniques enable integrated exploration of the mechanisms by which similarity arises. On the other hand, the trendy interest in development can effectively enrich our definitions of homology and our methods to individuate it. The study of developmental processes calls for a comparison at different developmental stages, overcoming the restriction to adults, which has been the focus in classical comparative studies [4]. Too often, comparative neurobiologists have considered brain evolution as the transformations of adult brains over time A more extensive interest in dynamic processes can help unveiling the plastic changes of the brain throughout life. To give a simple example, the developing human brain seems to be different at the functional neuroanatomy level from the adult brain, even in processing single words. Another puzzling problem is the genesis of novelty and its adaptive value. Interestingly enough, very recent molecular investigation on primates suggest that the human brain has probably experienced pronounced evolutionary changes in gene expression during its most recent history [3] and that the evolution of human cognitive abilities was accompanied by adaptive changes in brain metabolism [6].

8

A. Fasolo

These results are open to different theoretical hypotheses and should not overinterpreted, but they suggest that processes of fast genetic reorganization might sometimes occur. In the light on these considerations, a main question presents itself: what are the adaptive pressures behind brain and behavior novelties in evolution? We have no answer yet, but we can agree with the original statement by Williams, in his [15] Adaptation and Natural Selection, frequently quoted in evolutionary psychology, but not so frequently exploited: “Evolutionary adaptation is a special and onerous concept that should not be used unnecessarily, and an effect should not be called a function unless it is clearly produced by design and not by chance. When recognized, adaptation should be attributed to no higher a level of organization than is demanded by the evidence.” A new emphasis on homology in evolutionary biology (the persistence of theoretical problems notwithstanding), may offer new powerful tools for an effective comparative analysis, and may thus help distinguishing between strict biological correspondence and loose metaphoric representations of behavior, which are the mere result of an uncritical assumption of an evolutionary stance. Especially in cases of highly complex behavior, ethics being a paradigmatic example, biology and culture are certainly tightly entrenched: the claim that these kinds of behavior have evolutionary bases is simply a truism. The interesting point would be the possibility to identify the characters, if any, which show continuity and can be challenged by a homological analysis. The evolution of the brain involved a complex set of relationships among individual structures, both at the quantitative and the qualitative level. As aforementioned, there is some controversy concerning this idea, but the core problem (e.g., whether changes are directly selected or not) remains unsolved. It seems plausible, however, that some processes are related to environmental pressures, while others emerge in response to the need for more flexible answers, and still others are part of a less specific and foreseeable ecological niche. Likewise, brain structures have developed along several lines, and one usually finds a “mosaic-like” pattern even within a particular line. In such a mosaic of integrated parts, whatever the evolutional process might have been, at least a part of the variation has not been selected per se, but it represents a collection of exaptations [5]. For instance, the molecular evolution of ASPM gene in hominoids may indeed be an example of a molecular exaptation, in that the originally selected function of ASPM was for something other than large brain size, since the ASPM gene sequence shows accelerated evolution in the African hominoid clade, and this precedes hominid brain expansion by several million years [8]. The idea that novelty may arise from and exaptation (“functional cooptation” in Darwin, then “pre-adaptation” in Ernst Mayr) can have strong impact on our views. Three typologies of processes, i.e. classical Darwinian adaptations by natural selection; the functional shift, by natural selection, from a previous function to a secondary one; spandrels and other side effects with no adaptive reasons in their beginning, possibly co-opted by natural selection in new external conditions can extend the taxonomy of fitness [5,10].


9

6 Cognition and Reasoning Moving from comparative neuroanatomy to modern cognitive neuroscience, Giorgio Vallortigara explores recent research updating Darwin’s implicit suggestion that there maybe primitive neural pathways that ensure a bias toward sensory cues about other living things, in particular members of the same species. There has been of course a long road from the primitive animacy detectors that we can see operating even in simple brains to the intricacies of agency attribution and theory of mind of human beings. Nonetheless, the origins of beliefs in supernatural things and of our intuitive dualism seem to be deeply rooted in natural history. “Thus reason does not have to keep repeating why it holds itself to be so important if it can see how it became necessary and under what conditions it is in fact indispensable.” Volker Gerhardt believes that evolutionary theory can liberate reason from the burden of its thousands of years of self-confirmation and lead it back to the conditions that preceded it that are themselves not yet rational. It might not exist any other problem that the natural sciences and the humanities should take a greater interest in. For it is in the natural elucidation of the origin and the potential achievements of reason and consciousness that both fields have the chance to shed light on themselves as well and to clarify why they not only emerged from the same impulses of curiosity, knowledge, and rational guidance, but continue to depend on one another. Finally, Pievani reflects on the current status of theory of evolution: how it changes and grows, remakes itself keeping alive and reinforcing its Darwinian explanatory core. The starting point is the awareness that the capacity of assimilation of scientific novelties by Modern Synthesis (MS) seems to be progressively declining. The problem is seemingly no longer its “incompleteness”, but the adequacy of the whole conceptual structure of the theory [5]. Using Imre Lakatos’ methodology, Pievani argues that the transition in progress from the MS to the so called “Evolutionary Extended Synthesis” (ES) [12] could be represented as a shift from a previous evolutionary research, and a new evolutionary research program, with an extended Neo-Darwinian core and a protective belt of new assumptions and auxiliary hypotheses with a pluralistic and integrative explanatory approach. Promising and advanced researches – like those concerning evolutionary developmental biology (Evo-Devo), epigenetics, multiple ways of speciation and the role of structural internal constraints – find in this perspective a realistic interpretation as theoretical and empirical novelties with huge implications, nevertheless not incoherent with an extended Neo-Darwinian explanatory core. Such approach seems also useful discussing the extension of evolutionary models in non biological fields, in order to avoid just metaphorical forms of “ultra-Darwinism”. Summing up, the debate on evolution is still open and strives us to exchange and change ideas. What may be our philosophical and scientific endeavour, we can agree with Michael Ruse, expecting “that in fifty years or a hundred years we will still have the theory of the Origin around. Great, precisely because it does not

10

A. Fasolo

stand still, but remakes itself and grows and changes by virtue of the fact that it gives such a terrific foundation. Is Darwinism past its sell-by date? Not by a long chalk yet!”

References 1. Bell MA, Futuyma DJ, Eanes WF, Levinton JS (2010) Evolution since Darwin: the first 150 years. Sinauer, Sunderland 2. Dewey J (1909) The influence of Darwin on philosophy, «Popular Science Monthly», (1910) reprinted in The influence of Darwin on philosophy and other essays in contemporary thought. Indiana university Press, Bloomington 3. Enard W, Khaitovich P, Klose J et al (2002) Intra- and interspecific variation in primate gene expression patterns. Science 296(5566):340–343 4. Fasolo A (2006) The nature of resemblance, homologies in the nervous system, and behavior. In: Boniolo G, De Anna G (eds) Evolutionary ethics and contemporary biology. Cambridge University Press, Cambridge, pp 56–73 5. Gould SJ (2002) The structure of evolutionary theory. Harvard University Press, Cambridge, MA 6. Khaitovich P, Lockstone HE, Wayland M et al (2008) Metabolic changes in schizophrenia and human brain evolution. Genome Biol 9(8):R124 7. Kirschner M, Gerhart J (1998) Evolvability. Proc Natl Acad Sci USA 95(15):8420–8427 8. Kouprina N, Pavlicek A, Mochida GH et al (2004) Accelerated evolution of the ASPM gene controlling brain size begins prior to human brain expansion. PLoS Biol 2(5):e126 9. Minelli A (2011) A principle of developmental inertia. In: Halligrimsson B, Hall BK (eds) Epigenetics, linking genotype and phenotype in development and evolution. University of California Press, Berkely, pp 116–133 10. Pievani T (2003) Rhapsodic evolution: Essay on exaptation and evolutionary pluralism. World Futures 59:63–81 11. Pigliucci M (2008) Is evolvability evolvable? Nat Rev Genet 9(1):75–82 12. Pigliucci M, M€uller GB (2010) Evolution – the extended synthesis. MIT Press, Cambridge, MA 13. Michael R (2009) Philosophy after Darwin: classic and contemporary readings. Princeton Press, Princeton 14. Wake DB, Wake MH, Specht CD (2011) Homoplasy: From detecting pattern to determining process and mechanism of evolution. Science 331(6020):1032–1035 15. Williams GC (1996) Adaptation and natural selection. Princeton University Press, Princeton 16. Wittgenstein L (1961) Tractatus logico-philosophicus. Routledge & Paul Kegan, London

Idola Tribus: Lamarck, Politics and Religion in the Early Nineteenth Century Pietro Corsi

Abstract There is no doubt that traditionally the history of evolutionary ideas has been and is Darwin-centred. I have no dispute with this, being a convinced “Darwinian”, in spite of years of work I have devoted to study Lamarck and the many non-Darwinian theories of evolution current in Europe and the United States before and after 1859. Whereas historians have paid some attention to post-Darwinian, non Darwinian theories, pre-Darwinian theories have been much neglected. Attention is usually paid to so-called “Lamarckian” attitudes present in European natural history debates from the early 1800s to the 1850s, only to conclude that Lamarck played no role, was almost unanimously neglected and in any case unanimously vituperated. This was hardly the case. However, the aim of my paper is not to vindicate Lamarck, but to argue that even concentration on Lamarck would amount to gross anachronism. After analysing reasons – essentially political and religious – that have been given to explain the alleged oblivion into which Lamarck’s works had fallen (if they ever rose to attention) I will examine evidence concerning the wider debate on Lamarck’s ideas within the medical literature of the 1810s and the 1820s. This will open up a new research area, focussed on the translation into French of major German authors (Meckel, Tiedemann, Carus, Treviranus, Burdach, Oken) and on the attempts to re-formulate key Lamarckian tenets in the terms of German natural philosophy, comparative anatomy and embryology, and medicine. The debate on the development of life – historical and embryological – was wider and much more interesting than the debate on Lamarck’s own theories, which in any case well deserves to be rescued from oblivion.

P. Corsi (*) The Old Boys High School, University of Oxford, Oxford, UK e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_2, # Springer-Verlag Italia 2012

11

12

P. Corsi

All differences taken into account, Lamarck and Darwin shared the common destiny of being often identified with doctrines they never upheld, or not exactly in the form history has attributed to them. Over the last century and one half, wave after wave of the recurrent debate on “Lamarckism” vs. “Darwinism”, and the repeated rituals of centenary and other anniversary celebrations have done much to obscure the real contribution of the two naturalists to the debates on evolution. In saying so, I am of course taking for granted several assumptions, some of which will be spelled out and discussed in the following pages. A major assumption which will not be critically scrutinized, and is presented here as a comment at the end of one year of world-wide celebrations, is that in-depth and easily available historical studies on Lamarck and Darwin have been rarely read or consulted by a good number of commentators who during 2009 have been very active explaining who Darwin really was. Nor have they been consulted by the much lower number of those who remembered that 2009 marked not only the bicentenary of the birth of Charles Darwin, but also of the publication of the Philosophie zoologique, one of Lamarck’s key evolutionary texts. The impression one gets, after reading, viewing, or listening to a statistically relevant portion of what has been said on Darwin during 2009 through several continents and languages, is that his works, as those of Lamarck, are not that well known, and that the work of professional historians who have engaged the primary sources is scarcely taken into account. This is not a novelty, after all: since the early 1800s much of the debate on what we call today “evolutionary” doctrines was carried on without much attention to the actual articulations of the “scientific” arguments under discussion. Before stating and developing the key themes of my paper, let me provide only one example of what I peremptorily stated above. There is no doubt that the doctrine of the inheritance of acquired characteristics is universally regarded as the cornerstone of Lamarck’s theory and the major point of difference with Darwin and Darwinism. Yet, as Jean-Gayon has persuasively argued, and a rapid search by word of the Lamarckian corpus available on line will confirm, Lamarck never spoke of the theory of the inheritance of acquired characteristics.1 He most surely believed that new needs originate new behaviours, and new behaviours increase or decrease the size and functions of the solicited organs, to the point that new species and genera are formed. Life is thus constantly transformed, since the process is cumulative through inheritance. This was a conviction he shared with many authors active at the end of the eighteenth and at the beginning of the nineteenth Centuries, to the point that early critics of Lamarck rarely complimented or reproached him for this. The key issue when discussing Lamarck was always whether the process of change he had described was sufficient to overcome the species or the genus barrier – a point some were ready to concede – as well as higher divides (family, order) – which very few granted. Fifty years later, the same reaction characterized the early

1

Jean Gayon, “Lamarck Philosophe”, in P. Corsi et al., Lamarck philosophe de la nature, Paris, PUF, 2006, pp. 9–35. See P. Corsi, http://www.lamarck.cnrs.fr/ for the complete edition of Lamarck’s theoretical works, his manuscripts and herbarium.

Idola Tribus: Lamarck, Politics and Religion in the Early Nineteenth Century

13

(and later) debates on natural selection: many saw it as a plausible mechanism to explain the fixation of varieties, which could in no way put in doubt the constancy of species, or of genera. The interesting question that emerges from carefully comparing the relevant Lamarckian and Darwinian texts, is that the capability of organisms to change and to pass on to the next generation whatever was gained or lost during their lifetime was severely limited in the case of Lamarck, and less so with Darwin. For Lamarck, only very young organisms, in which the tissues were still very soft, and the circulation of blood, nymph, and the nervous and other fluids was particularly brisk, showed a potential for adaptive change: never the adults. This was not Darwin’s opinion. When presenting the ill-fated and little studied theory of pangenesis, among other phenomena of heredity Darwin sought to explain how a change that occurred at a given point in the life of one organism tended to appear again at the same stage of individual development in his progeny. Furthermore, whereas Lamarck simply took up a widely shared, almost commonsensical belief that the characteristics of the parents were passed on to the next generation, Darwin spent time and ink to understand how this was possible, even discussing similar theories put forward by authors such as Georges-Louis Leclerc, Comte de Buffon (1707–1788) and Charles Bonnet (1720–1793), on whom Huxley had called his attention.2 Lamarck spent much less time on the matter: he simply argued that since the male seminal fluid (akin to electricity and magnetism) acquired specific peculiarities within each type of organism, it was legitimate to infer that the same fluid would take up slightly different anatomical and functional properties by circulating through an organism that had undergone a very slight change during the early phases of its life. Indeed, for Lamarck, fully blown characteristics were the end result of a cumulative process of very minor changes within the fluid dynamics internal to all and every organism. Thus, if a new need was requiring a more pronounced use of a given organ, thereby increasing the flow of blood, nutritional and nervous fluids to that part, what was passed on to the next generation (provided the young individuals that had gone through the same process reproduced together when adults), was not a character that as yet did not exist, but the slight change in the pattern of the fluid dynamics and the slightly modified features of the seminal fluid. On the contrary, Darwin admitted the inheritability of changes occurring in a single parent, and asked himself how these could be maintained through successive generations. This is not to conclude that Darwin was more Lamarckian than Lamarck, but to insist on the fact that the mere reading of the works of Darwin and Lamarck would prevent all hasty and easy generalizations. Even though rarely read by those who should, the scholarship on Darwin of the last 40 years has been on the whole excellent and has powerfully contributed to a

2

See C. Darwin, The Variation of Animals and Plants under Domestication, 2 vols., London, J. Murray, 1868, vol. 2, Ch. XXVII, “Provisional hypothesis of pangenesis”, pp. 357–404.

14

P. Corsi

less anachronistic appreciation of the man, his career and doctrines.3 The case of Lamarck, on which I will devote the main bulk of my paper, is to some extent quite different. There are of course excellent studies of his work and career, though the writings of the French naturalist have not been translated or edited with the same alacrity and systematic dedication.4 There is no correspondence left worth mentioning, no notebooks, no autobiographies or diaries. Much of the Lamarckian manuscripts are in fact drafts or final versions of printed works. Lamarck was very parsimonious with information about himself, his life and thoughts, to the point that much of the scarce biographical hints we have are due to members of his family, his enemy Cuvier or to a young medical practitioner who interviewed him in the early 1820s.5 Moreover, whereas over the last 20 years or so important scholarship has appeared offering insights into the wider natural history scene (institutional, intellectual and social) of the United Kingdom, the same cannot be said of France during the times in which Lamarck was active. In other words, the scholarship on Lamarck has not incited new studies on the wider scientific and institutional context characterizing the life sciences during the early decades of the nineteenth century in France.6 The rare albeit excellent exceptions to the rule have not helped us to gain a less anachronistic view of contemporary priorities, actors and debates. The set of traditional assumptions concerning the context of Lamarck’s work remain stubbornly unchanged, in spite of growing evidence that should advice historians to enlarge the scope of their research. It is a few of these implicit, often untold assumptions I wish to tackle in the following pages. Basically, they turn around a major conviction, the total or almost total isolation Lamarck lived in. This assumption generates in its turn a host of further assumptions – if not prejudices – asked to perform a causal role in the narrative. They can be ranged, historically and thematically, from the (usually French) patriotic and whiggish explanation that Lamarck was born too early, or that he was seeing too far, to the less charitable (usually Anglo-American, pro-Darwinian) view that he was simply wrong, overwhelmed by top brass of science such as Georges Cuvier (1769–1832), PierreSimon Laplace (1749–1827), or Antoine Lavoisier (1743–1794) and his pupils.

3

I will only refer here to the biographies by A. Desmond and J. Moore, Darwin, London, Michael Joseph, 1991 and Darwin, Oxford, Oxford University Press, 2007; and J. Browne, Charles Darwin, 2 vols., London, Jonathan Cape, 1995–2002. 4 See for instance R. Burkhardt, The spirit of system: Lamarck and evolutionary biology, Cambridge, MA, Harvard University Press, 1977, 1995. 5 Georges Cuvier,. “E´loge de M. de Lamarck, lu a` l’Acade´mie royale des sciences le 26 Novembre 1832”, in Me´moires de l’Acade´mie royale des sciences de l’Institut de France, 13 (1831–1833), pp. i–xxx; Isidore Bourdon, “Lamarck”, Dictionnaire de la conversation et de la lecture, 34 (1837), pp. 265–269. 6 See for instance J. Secord, Victorian sensation: the extraordinary publication, reception, and secret authorship of Vestiges of the Natural History of Creation, Chicago and London, University of Chicago Press, 2000, and J. Endersby, Imperial nature: Joseph Hooker and the practices of Victorian science, Chicago and London, University of Chicago Press, 2008.


15

He had no chance to be listened to in a world moving towards disciplinary specialization and epistemological rigour. A second assumption concerns the inevitability of Lamarck’s isolation in the increasingly conservative political climate of the Consulate and the Empire, and in the ultra-conservative intellectual atmosphere of the restored monarchy. His materialistic biology and transformist doctrines (it is claimed) were unacceptable to authorities determined to curb any form of political and intellectual subversion. Finally, the third assumption we are going to examine below is the one concerning the audience of Lamarck’s works. Followers of various versions of assumptions one and two will find this third point completely superfluous. To them, Lamarck had no audience worth talking about, at least until the 1820s, and even then the few who paid any attention to him did not, in fact, support his views as the old naturalist would have wished. In France as well as in Europe, Lamarck’s materialism found sympathetic hearing only within the radical fringes, thereby adding to the already long list of reasons people had to dismiss him outright.7 The way in which the assumptions we have sketched above have been argued by historians does not lack plausibility and evidential support. Yet, consensus has been gained at the price of restricting the research horizon to the point of neglecting major features of natural history practices and debates of the early nineteenth century, in France as well as elsewhere in Europe.

1 Lamarck Versus Institutional Science Very few historians of early nineteenth century life sciences appear to doubt that the major educational and institutional reforms introduced by successive revolutionary governments, the Directory, the Consulate and the Empire deeply changed the social and intellectual practices of research within the complex articulation of disciplines still constituting the “histoire naturelle”. To a significant extent, they are absolutely right. In 1792, 1793 and 1799, two naturalists occupying the opposite sides of the epistemological spectrum in the debate over natural history agreed that France was not doing much, after all. Jean-Claude de la Me´therie (since 1793 simply “Delame´therie”) and the then still little known Cuvier insisted that Germany was better equipped than France in several sub-domains of natural history. Cuvier pointed out that almost every German university town was publishing its own scientific or medical journal and hosted important private and public collections. In France, almost everything was concentrated in Paris, and Parisian naturalists were too happy to sit on the top of their monopolistic privileges to care about sharing their knowledge with colleagues in the provinces and abroad. As a

7

The best known and best argued representative of the view that Lamarck was acceptable only to extreme radicals is Adrian Desmond, The Politics of Evolution. Morphology, Medicine and Reform in Radical London, Chicago and London, University of Chicago Press, 1989.

16

P. Corsi

consequence, France was rather poor in periodical publications, since only a handful had survived the revolutionary years, and there were not that many even before 1789, for that matter.8 In the space of a few years the situation changed dramatically and unpredictably. The Revolutionary armies engaged in the systematic plundering (which they called “confiscation”) of conquered lands, to finance the huge state deficit and the costs of the war. Cash, precious minerals, paintings and sculptures, natural history and scientific instrument collections took the road to Paris in hundreds of over-charged wagons. The Museúm national d’histoire naturelle, established in June 1793, was the ideal place were natural history collections could be hosted, catalogued and studied on behalf of the Republic of knowledge, which did not know of frontiers or wars. Confiscations were undertaken with a higher view in mind, the benefit of mankind, French authorities insisted.9 By 1802, Paris hosted the largest and richest natural history collections ever assembled in Europe. Naturalists from all over the Continent had to pay frequent visits to the French capital: some, undoubtedly, to pay due homage to the new rulers; others, because they had to keep up with their own work. The local German collections Cuvier had extolled in 1799 were no more sufficient to guarantee cutting edge research. French scientific publishing also benefited from the new impulse successive governments accorded to the practice of science.10 The at times purely symbolic

8 Georges Cuvier, “Extrait d’une Notice biographique sur Bruguie`re, lue a` la socie´te´ philomathique, dans sa seánce geńe´rale du 30 nivoˆse an VII”, in Magasin encyclope´dique, 5th year, vol. 3 (1799), pp. 42–57; Louis Marchant, Lettres ine´dites de Georges Cuvier a C. H. Pfaff sur l’histoire naturelle, la politique et la litte´rature, Paris, Victor Masson, 1858, p. 78: “Les sciences ont aujourd’hui peu de dignes preˆtres en France, et cette pauvrete´ est d’autant plus peńible, que l’on se souvient encore de l’ancien ećlat dont elles ont brille´”; Jean-Claude Delame´therie, “Discours pre´liminaire”, in Journal de physique, 42 (1793), p. 7. See also A.-L. Millin, “Journal d’histoire naturelle”, in Magazin encyclope´dique, 1, n. 8 (8 dećembre 1792), pp. 57–60, “L’Allemagne voit paroıˆtre un grand nombre de collections, et de recueils d’histoire naturelle”, p. 57. 9 For two recent systematic studies of the accumulation of collections in Paris see B. Daugeron, Apparition-Disparition des Nouveaux mondes en Histoire naturelle, Enregistrement-Epuisement des collections scientifiques (1763–1830), Paris, EHESS, The`se de doctorat, 2007, 2 vols.and P.-Y. Lacour, La Re´publique naturaliste. Les collections françaises d’histoire naturelle sous la Re´volution, 1789–1804, Florence, European University Institute, Ph. D. Dissertation, 2010, 2 vols. It is interesting to point out that in his biographical notice of Bruguie`re (see n. 8) Cuvier complained that the collections amassed at great public expense were now collecting dust at the Museúm, since no one appeared to work on them. This too was soon to change, but systematic exploitation of the conquered natural history riches only started after 1802, that is, after Cuvier became full professor there. The political innuendos of Cuvier’s astonishing biography of Bruguie`re, his equally astonishing veiled attacks against colleagues working at major State institutions have never been analyzed in detail. 10 Amongst many, the testimony of Louis Marchant, Lettres ine´dites de Georges Cuvier, is telling, p. 30: “C’e´tait une e´poque tre`s-favorable pour les sciences et ceux qui les cultivaient; le premier consul se trouvait tre`s-honore´ du titre de membre de l’Institut, il le mettait en teˆte de tous les autres. Les premiers hommes de la science, comme Laplace, Chaptal, Monge, e´taient en meˆme temps les


17

encouragement lasted until the end of the 1790s, followed by real investments – especially as far as the Museum d’histoire naturelle was concerned, during the early 1800s. Yet, already in the second half of the 1790s the rhetorical and ideological support for science-oriented activities was sufficient to massively increase the market for natural-history publications: collective works of Buffon, dictionaries and encyclopaedias, textbooks and innovative surveys of new or renewed domains of research (among which Cuvier’s Leçons d’anatomie compareé), manuals for the new school systems found eager buyers and were exported throughout Europe and the Americas.11 Unfortunately, this feature of the French publishing market has been little studied and even less appreciated. Furthermore, no attention has been paid to the dense population of naturalists surviving thanks to their pen. Historians have tended to ignore a highly articulated editorial, epistemological and research scene and have instead concentrated their attention on a handful of individuals and institutions. As it is often the case within the history of science, our contemporary concept of proper scientific practice deeply influences our reading of the past. In spite of the pioneer work of Dorinda Outram, published in 1984, historians insist (at times very ably indeed) that the natural history scene was dominated by Georges Cuvier, who exercised an undisputed leadership, set the standards, and marginalized whoever did not conform to his anti-speculative, matter of fact approach to natural knowledge.12 The Museúm national d’histoire naturelle and the Institut de France were the strongholds from where Cuvier, the so-called Napoleon of intelligence, manoeuvred his troops and kept epistemological order. Outram richly documented the difficulties Cuvier experienced, the set-backs he had constantly to suffer, and pointed out that many of the institutional gains the naturalist scored were often the consequence of his political shrewdness and power rather than the indication of his undisputed scientific authority. When in 1818 a distant relative and admirer of Cuvier, Jean-Jacques Coulmann (1796–1870), visited London, he was amazed to notice that the anatomist was better known in the English capital than in Paris.13 As I have myself documented, Cuvier’s leadership was constantly challenged, in some

premiers aux affaires. L’institution grandiose du Jardin des plantes, a` laquelle des savants spećiaux d’une grande ce´le´brite´ e´taient attache´s pour chaque branche de l’histoire naturelle, pour la geógnosie, la geólogie, pour la chimie theórique et pratique, a` laquelle se reliaient les grands museés nationaux, avait surtout une grande part dans cette sollicitude et ces encouragements.” 11 For further contemporary testimonials, see, among others, F. W. Blagdon, Paris as it was and as it is, London, C. and R. Baldwin, 1803, vol. 2, p. 582, and passim. See also P. Corsi, “After the Revolution: Scientific Language and French Politics, 1795–1802”, in M. Pelling and S. Mandelbrote, eds., The Practice of Reform in Health, Medicine, and Science, 1500–2000, Aldershot, Ashgate, 2005, pp. 223–245 12 D. Outram, Georges Cuvier: Vocation, Science and Authority in Post-Revolutionary France, Manchester, Manchester University Press, 1984. 13 J -J Coulmann, Re´miniscences, Paris, Michel Le´vy fre`res, 1862–1869, vol. 1, p. 233: Coulmann was the younger brother of the wife of General Frederic-Louis-Henri Walther (1761–1813), Cuvier’s first cousin. Outram, 1984, has called attention to the role Walther played in introducing Cuvier to powerful figures in Paris in early 1795, when Walther was already a significant figure within the army.

18

P. Corsi

cases openly derided, and the publications directed to the general public he sponsored failed miserably (his famous and very successful specialized works were too expensive to reach the ordinary reader), to the joy of his opponents. Cuvier did try his best to convince contemporaries that he was the depositary of true scientific values and achievements. His e´loges of deceased academicians, his reports to the Emperor on the progress of science in France and Europe spared no effort to turn celebration and highly selective information into prescription. Yet, year after year the Journal de physique devoted the entire January issue to review scientific publications and achievements throughout Europe. Delame´therie, its editor, made no secret of the fact that he was challenging Cuvier’s rival accounts. For instance, Cuvier never mentioned current debates on spontaneous generation, to him a nonsubject, whereas Delame´therie informed readers – and the historians – of how many variants of spontaneous generation doctrines were available in Europe during the 1800s and the 1810s. I mentioned above the highly competitive market of dictionaries and collective works. During the 1790s, Charles-Nicolas-Sigisbert Sonnini de Manoncourt (1751–1812), a former collaborator of Buffon, launched an edition of his master’s work, to which scores of volumes were added, to turn it into a “Complete course” of natural history. 127 volumes were published and sold to over 1,400 subscribers throughout France and Europe.14 In 1803 the same editorial team launched the Nouveau dictionnaire d’histoire naturelle, completed in the space of 2 years.15 The 24 volumes, relatively cheap set was sold to some 2,300 readers at Continental level.16 Cuvier reacted with anger, as I have already documented elsewhere. In 1804 he issued an announcement inviting readers to subscribe to the forthcoming Dictionnaire des sciences naturelles, placed under the editorship of his brother Fre´de´ric (1773–1838). Adopting a tone of ease and superiority, Cuvier warned readers not to buy the rival publication, which was not issued by the Professors of the Museum as his own dictionary was, but by amateurs without much experience.

14

Charles-Nicolas-Sigisbert Sonnini de Manoncourt, ed., Histoire naturelle, geńe´rale et particulie`re, par Leclerc de Buffon. Nouvelle e´dition, accompagneé de notes, dans lesquelles les supple´mens sont inse´re´s dans le premier texte, a` la place qui leur convient. [. . .], Paris, F. Dufart, Year VII (1798)-1808. The list of more than 1400 subscribers does not take into account direct sales from the printers and publishers. 15 Julien-Joseph Virey, Nouveau dictionnaire d’histoire naturelle appliqueé aux arts, a` l’agriculture, a` l’ećonomie rurale et domestique, a` la me´decine, etc., par une Socie´te´ de naturalistes et d’agriculteurs, 1803–1804. 1st ed., 24 vols., Paris, De´terville. 1816–1819; 2d ed., 36 vols., Paris, De´terville. Already in 1807 the publishers were considering a second edition. 16 For an interesting contemporary comment on the Nouveau dictionnaire see H. Redhead Yorke, Letters from France in 1802, 2 vols., London, H. D. Symonds, 1804, vol. 2, p. 333: “This precious work is published at so reasonable a price, that the sale will scarcely defray the expenses of paper and printing. It is essentially a patriotic undertaking by Sonnini, Virey, Parmentier, Huzard, Bosc, Olivier, Latreille, Chaptal, Cels, Thouin, Du Tour, and Patrin, men possessed of great knowledge of the subjects of which they treat”.


19

Cuvier badly lost the war of dictionaries. Only volume 5 of the Dictionnaire des sciences naturelles appeared and only a handful of subscribers received copies of volume 6. In 1816, the publishers of the Nouveau dictionnaire started a new expanded edition. This time, 36 volumes were distributed in the space of 3 years to almost 3,000 subscribers. Cuvier immediately retorted by changing the cover of the first 6 volumes left unsold in 1804–1805, and launched the Dictionnaire des sciences naturelles a second time over. Volume 60 was issued only in 1830, and a careful perusal of the entire set (a task historians have surprisingly failed to undertake) reveals that Cuvier and his brother did not, on the whole, spend much time on it. Cuvier’s dictionary is a rather disappointing publication, lacking a firm editorial line and, at time, even basic supervision. Embarrassingly, determined enemies of Cuvier were allowed to write entries that contradicted what the famous naturalist was preaching since his coming to Paris, as it was the case with the entry “Matie`re verte”, confided to Jean-Baptiste Bory de Saint-Vincent (1778–1846), who did not miss the ironic chance of promoting spontaneous generation on the pages of a publication nominally under the tutelage of Cuvier.17 One final point needs to be emphasized. In the printed announcement we mentioned above, Cuvier insisted that his dictionary represented institutional science, and his rivals were only members of the unruly crowd of unreliable if not desperate amateurs. If one compares the list of contributors to both dictionaries, one will immediately realize that Cuvier did not tell the truth. The rival dictionary could boast contributions by Jean-Antoine Claude Chaptal (1756–1832), member of the Institut and until 1804 Minister of the Interior; of Andre´ Thouin (1746–1824), the famous head gardener of the Jardin des Plantes and himself member of the Institut; and of Antoine-Augustin Parmentier (1737–1813), the ultra-popular pharmacist, lover of potatoes, and expert in food preservation, among many other accomplishments. Parmentier, it is appropriate to mention, was the main sponsor of the Nouveau dictionnaire d’histoire naturelle: in no way could he be considered an amateur. Thus, even Cuvier was at pain to draw a clear line between the “institutional” science he was supposed to lead and the actual articulations of natural history practices and publications over which he clearly exercised little control. During the 1810s and the 1820s, a series of popular generalist encyclopaedias and of more specialized medical and natural history dictionaries did not hesitate to openly challenge Cuvier’s authority. By 1816, Cuvier almost completely withdrew from all teaching engagements, paid assistants and secretaries to do his job, and became a full time member of the political establishment. Authors ranging from Louis Antoine Desmoulins (1794–1828), E´tienne Geoffroy Saint-Hilaire (1772–1844) and François-Vincent Raspail (1794–1878) did not refrain even from alluding to the fact that Cuvier was limiting himself to the writing of prefaces to the various, very expensive volumes of the Re`gne animal or the Histoire naturelle des poissons compiled by a host of ghost writers and researchers: he

17 J.-B. Bory de Saint Vincent, “Matie`re verte”, in Dictionnaire des sciences naturelles, 29 (1823), pp. 314–336.

20

P. Corsi

had become an author of coffee table books.18 The question is not whether the allegations (undoubtedly exaggerated) were true or not. The point to be emphasized is that during the 1820s Cuvier’s authority was challenged at various institutional and editorial levels, and the only power he could exercise was on his own salaried staff: within certain limits, as we shall see below. Thus, the view that Lamarck was silenced by Cuvier’s dominant and domineering position within the hierarchy of contemporary natural sciences cannot be substantiated. Cuvier hardly managed to silence anyone, even colleagues he hated, such as the geologist and monarchist Barthe´lemy Faujas de Saint-Fond (1741–1819, whom he nick-named “Sans fond” in reference to his colleague’s constant need for money), Geoffroy Saint-Hilaire (who was writing with the style of a “cook”, Cuvier mused), Lamarck (a lonely man dominated by his imagination), or wizards of the natural history publishing industry such as Delame´therie (editor of the then famous Journal de Physique) or Sonnini de Manoncourt. The latter repeatedly and publicly made fun of his junior colleague, who pretended to discipline all the rest of the community of naturalists by waving at them his pathetic school teacher’s stick: people knew better, and bought the works he, Sonnini, was producing.19 If one pays close attention to Cuvier’s career after the very early 1800s, one is struck by the decreasing time he spent teaching and undertaking first hand research. He was often absent from Paris, and when in town he devoted much of his seemingly boundless energy to perform administrative duties and to keep his many State jobs. Staying in power is never a given, and Cuvier, as contemporary witnesses such as Stendhal, de Chateaubriand, or Cuvier’s distant relative we mentioned above testify, worked very hard to keep surfing the treacherous, incessantly breaking waves of contemporary power.20 The assumption that Cuvier exercised a decided and unquestioned authority over the natural history disciplines of his time can be maintained only at the price of ignoring four fifths of the natural history scene of the time. As we will argue below, Cuvier did not exercise full authority even on his direct collaborators, who were wholly dependent on his good will to continue to earn a salary. They obeyed, did what they were told, but in turn actively supported naturalists who did share their admiration for the master, but felt free to pursue lines of research Cuvier was very critical of, or openly despised. As a client of power, Cuvier was hardly in a position to challenge power, even when decisions concerning his own career and appointments were taken that forced

18

Antoine Desmoulins, Histoire naturelle des races humaines, Paris, Me´quignon-Marvis, 1826, p. viii; François-Vincent Raspail, “Coteries scientifiques”, Annales des sciences d’observation, 3 (1830), pp. 151–159, p. 157; on Geoffroy Saint-Hilaire’s repeated attacks against Cuvier, see Corsi, The Age of Lamarck, ch. VIII. 19 I have discussed Sonnini’s defiant attitude against Cuvier in The Age of Lamarck, pp. 36–38. 20 Stendhal, The Life of Henry Brulard, translated and with an introduction by Jean Stewart and Bert C. J. G. Knight, London, 1958, p. 180


21

him to swallow very unsavoury compromises. One single example will suffice. When the highly respected former collaborator of Buffon, Louis-Jean-Marie Daubenton, died at the end of December 1799, Cuvier aspired to succeed him to the Chair of mineralogy at the Colle`ge de France. This was to him an important step forward, and a prestigious, highly symbolic promotion. Delame´therie, who had spared no ink in publicly deriding his junior colleague, whom he depicted as an able yet arrogant social climber, felt the chair belonged to himself: he was after all (in his own eyes at least) one of Europe’s most prestigious mineralogists. Politics played a key role in the appointment. Delame´therie was supported by General Bonaparte’s independently minded brother Lucien (1775–1840), and by his own brother Antoine (1751–1804), an opaque yet faithful “yes-man” of the First Consul Bonaparte. Antoine had helped Lucien to orchestrate and execute the coup-d’e´tat of Brumaire 1799 that imposed the Consular regime and established Bonaparte’s leadership. Almost on the day of the appointment Lucien and Napoleon quarrelled, and Lucien’s authority was greatly diminished. The chemist and successor to Lucien to the Ministry of Interior, ad interim in the fall of 1800, and fully in 1801, Chaptal, and his friend Bernard-Etienne de Lace´pe`de (1756–1825), a naturalist also very close to General Bonaparte, favoured Cuvier, who was duly appointed. Yet, political debts to Antoine Delame´therie had to be paid as well, and the letter of appointment specified that Cuvier was granted the chair, but JeanClaude Delame´therie was accorded the position of assistant. His salary was going to be one-third of the salary allotted to the full chair, which Cuvier had to pay directly to the hated rival.21 It was only in November 1802 that Cuvier was finally given a full chair at the Museúm, the same year in which he was appointed perpetual secretary to the First Class of the Institute. As Dorinda Outram pointed out several years ago, Cuvier would have been very pleased to know that historians would make him the undisputed emperor of natural sciences. This would have consoled him of the enormous efforts he kept producing to maintain his many jobs and his many salaries in the real world of politics. He had little patience with academic rituals – which he did nevertheless perform as an accomplished master – and did his best to revenge himself against his intellectual and political enemies. Whether he succeeded is of course another matter, and to assume that he managed to condemn Lamarck to a bitter isolation is precisely a groundless assumption.

2 The Politics and Religion of Science As we mentioned above, Lamarck has left precious little archival material; the thousands of pages of manuscripts still preserved are in fact, for the most part, drafts of his published works. Thus, we have only his printed works to try to understand

21

H. D. de Blainville, Observations sur la chaire d’histoire naturelle du Colle`ge de France, Paris, 1832.

22

P. Corsi

his standpoints on dramatic and burning issues such as politics and religion before and after the French revolution and during the Empire and the Restoration. As far as politics is concerned, Lamarck kept a low profile, though in 1794 he dedicated his Recherches sur les principaux faits physiques to Jean-Paul Marat, refusing, he added, earlier suggestions to inscribe the work to Louis Capet, the deceased King. As far as religion is concerned, some commentators have insisted on his mentioning the Deity here and there as evidence that Lamarck was at least a deist, though they failed to notice that reference to a Superior Being increased with the increasingly conservative intellectual and political climate of the Consulate, the Empire and the Restoration. As an eternalist who claimed that nothing can be created or destroyed in nature, since all elements exist since eternity; as someone who wrote that religious ideas were created and spread by self-interested elites aiming at dominating the majority of the population; and as someone who at the end of his life affirmed that there was no metaphysical principle sustaining human life and consciousness – no soul, in other words, there is little doubt that he was not a fervent nor even a lukewarm Christian, and I personally doubt he was even a deist. What we know for sure is that he waited a relatively long time before baptizing his children, and did so only in 1808.22 This was well into the Empire, when it was abundantly clear to everyone that the regime would not tolerate open profession of atheism. Lamarck’s post-1800 views, his transformist doctrines in particular, were indeed accused of leading to, or even of advocating atheism. Julien-Joseph Virey (1775–1846) explicitly linked Lamarck to atheism in the successful Nouveau dictionnaire d’histoire naturelle, and repeated his charges several times until the 1830s. A precious testimony has recently been unearthed by Herve´ Ferrie`re in his ground-breaking doctoral dissertation on Bory de Saint-Vincent.23 In 1804 Bory’s best friend, the entomologist JeanMarie León Dufour (1780–1865) was in charge of seeing through the press Bory’s Voyage dans les quatre principales ıˆles des mers d’Afrique since the author was away from Paris on military duties. Dufour unsuccessfully tried to convince Bory to suppress a chapter, in which the young naturalist sketched a non-Lamarckian evolutionary model for the history of the Earth and of life, inspired by current debates on the “Theórie de la Terre”: was he not aware, Dufour insisted, of what priests and bigots (“preˆtraille” and “bigotaille”) were saying against Lamarck? Prudence was called for, to avoid unnecessary danger and polemic. Though further research is required to establish the actual foundation and origin of this rumour, there

22

Raphae¨l Bange, “Les ressources de l’e´tat civil parisien pour l’histoire des sciences. L’exemple de Lamarck”, Bulletin de la Socie´te´ d’histoire et d’e´piste´mologie des sciences de la vie, 1 (1994), pp. 30–41. 23 H. Ferrie`re, Bory de Saint-Vincent (1778–1846): naturaliste, voyageur et militaire, entre Re´volution et Monarchie de Juillet; essai biographique, The`se de doctorat, 2 vols., Universite´ Paris 1, Pantheón-Sorbonne, 2001 and Bory de Saint-Vincent: l’e´volution d’un voyageur naturaliste, Paris, Syllepse, 2009.


23

is no doubt that Dufour is referring to something people talked about within natural history circles. Historians have often insisted on the atheistic tendency of Lamarck’s tenets to account for his alleged isolation, and I have myself pointed out instances which show Lamarck’s awareness of the risks he was facing. Though Lamarck has been credited to be one of the earliest proponents of the word “biologie” (yet by no means the first, as some historians love to repeat), the systematic analysis of the Lamarckian corpus reveal that the proud announcement of his new project, the establishment of biology, in January 1802, was followed only 6 months later by a stern disclaimer: his age, commitments and bad health would prevent him from carrying the project forward. In the Preface to the Philosophie Zoologique, the famous two-volume work he published in 1809 as textbook for the new Imperial University, Lamarck reassured readers that his biology was completely abandoned. Surprisingly, in the preface to the first volume of the Histoire naturelle des animaux sans verte`bres (1815) Lamarck informed his readers that he was working to establish a new discipline, for which not even a name existed, which he proposed to call “biology”. In a study I published a few years ago, I reconstructed the political reasons that made Lamarck aware, in July 1802, that his project, and the word he chose, “biologie”, could be associated to another word and project, “ideólogie”, then at the centre of intense political debate. As the ideologues wished to reform philosophy and dispense with metaphysics and religious tutelage, Lamarck wished to establish a science of life equally free from religious and philosophical preconceptions, and solidly grounded on a set of explicitly materialistic assumptions. In 1803 the ideologues were severely punished by General Bonaparte because of their republicanism, but also for their opposition to the partial re-establishment of the Catholic religion in the country, thanks to the Concordat of 1801. The second section of the Institut, devoted to the moral and political sciences, was closed down, and its members dispersed throughout the other sections. Many ideólogues retained a certain measure of influence, mainly through their work within the field of education and legislation, but were kept at a safe distance from any form of political influence and power.24 A man too proud to court powerful patrons, or simply socially inept, as Cuvier suggested, Lamarck well knew that he was in a much weaker position than representatives of ideólogie. A campaign against his tenets and philosophical propensities could have led to his dismissal, which would have meant total destitution for himself and his family. He therefore spared no words to reassure his readers and potential critics that he had learned the lesson, and would not persist in pursuing a line of research people saw as contrary to the sound principles of religion. In 1815, Lamarck believed, as many Frenchmen did, that the Chart the restored King Louis XVIII granted to the French people guaranteed full freedom of opinion and of expression. He thus took up again his biology project, though the language was now

24 Pietro Corsi, “Biologie”, in P. Corsi et al., Lamarck, Philosophe de la nature, Paris, PUF, 2006, pp. 37–64.

24

P. Corsi

more guarded and prudent. The last works he composed from 1816 through 1820 expanded upon his materialistic interpretation of psychological and intellectual phenomena, though here and there he paid lip service to the superior truths of Revelation, which were guiding and correcting research when the highest moral and metaphysical concerns were involved. During the 1820s, Lamarck’s health deteriorated, his blindness became total after 1818, and he withdrew from public life and teaching. The Institut granted him the privilege of getting the token extracompensation accorded to members who attended sessions: the old naturalist could not afford missing one. The question to be asked, one I did not ask myself in my article of 2006 on the politics of biologie, is the following: can we generalize the situation Lamarck experienced, and conclude that the practice of natural history was subjected to close scrutiny if not censorship during the Consulate, the Empire and the Restoration? The answer is complex, and all the evidence at our disposal suggests great prudence before embarking upon hasty generalizations. That Lamarck was afraid for his job and livelihood does not mean that others were as well. Then, as now, the danger of defending a minority or a fringe position was inversely proportional to the social and political weight of the single individual going public. A few examples will suffice to clarify this point. We have already referred to Delame´therie in connection with his appointment as assistant to Cuvier at the Colle`ge de France. Delame´therie was known as a die-hard materialist. Though he often used a language compatible with main stream traditional eighteenth century deism, Delame´therie liked to entertain foreign visitors on the different shadows of contemporary French atheism.25 In one particular instance, when accompanying a party of Englishmen on a private visit to the Museúm national d’histoire naturelle, he made fun of one of his guests, who, astounded by the beauty of the display of the richness of living nature, had made a comment on the clear indication the splendid collections offered of the existence of God: “He smiled and returned for answer, that I ought to recollect I was in an ecstasy”, his guest Henry Redhead Yorke (1772–1812) recalled.26 During the 1800s and the early 1810s, Delame´therie closely mirrored Lamarck’s publications, taking up almost the same topics and issues, to the point that a visitor like the Italian geologist count Giuseppe Marzari Pencati (1779–1836) could mistake works by Lamarck for works published by Delame´therie, as Cuvier himself did (for different reasons, needless to say). The differences between the two authors were significant, especially as far as the doctrine of the transformation of life throughout the history of the Earth was concerned. Delame´therie believed in a primeval Ocean in which rocks

25

On Delame´therie’s atheism, see H.. D. de Blainville, “Notice historique sur la vie et les ećrits de J.-C. Delame´therie”, in Journal de Physique, 85 (817), pp. 78–107, p. 89. 26 H. Redhead, Letters from France in 1802, vol. 1, p. 225. See also J. A. C. Sykes, ed., France in Eighteen Hundred and Two Described in a Series of Contemporary Letters by Henry Redhead Yorke, London, William Heinemann, 1906, p. 93. Sykes appeared to ignore the original work. His edition is marred by hilarious spellings of the names of the main actors of Parisian life in 1802.


25

and life were formed through countless ages thanks to processes of crystallization, and maintained that all life forms known to man developed from a restricted number of prototypes equally generated by specific forms of crystallization – all of which Lamarck firmly denied. Yet, there is no doubt that Delame´therie thought that Lamarck had copied some of his ideas, and wrote extensively on the action of habits in giving new shapes to organs – within the well defined limits of the original crystallization process that had established the prototypic form, one should hasten to add. On this subject his discussion was more detailed and sustained than Lamarck’s. Delame´therie too was a civil servant, not very well off, having decided to repay the heavy debts his brother incurred at gambling. Yet, his political connections and his high European reputation as editor of the Journal de physique – a periodical historians are very unwise to ignore – bought him a degree of free expression, higher than the one Lamarck felt was allotted to him. We have already mentioned the dark prophecy León Dufour addressed to his friend Bory de Saint-Vincent. The Catholic party would not forgive him for his materialist account of the history of the Earth and of life on it. It is interesting to note that Dufour too, as Marzari Pencati and Cuvier, appeared to believe that Lamarck endorsed the hypothesis of a primeval Ocean. What is more interesting from the point of view of our discussion is that no Catholic reviewer took up the challenge. As Herve´ Ferrie`re has brilliantly shown, Catholic reviewers were not nice to Bory, and even accused him of having deserted the famous expedition to the South Seas led by Captain Nicolas-Thomas Baudin (1754–1803) – which was indeed true, since Bory (together with other naturalists of the expedition) jumped ship at the Iˆle de France, today’s Mauritius, and refused to continue the journey. Yet, no one mentioned the materialist and possibly atheistic tendency of the book. Favourable reviewers also avoided any comment on the incriminated chapter, though only 3 years earlier the debate on the Theory of the Earth had aroused generous comment, and Delame´therie was never tired of providing new evidence for his own geological and biological views in the pages of the Journal de physique. So, why, contrary to the prediction made by Dufour, and in spite of religious attacks against Lamarck and his doctrines, friends and foes alike avoided commenting on Bory’s equally objectionable doctrines? We cannot know for sure and here again further research is required. Yet, the fact that Bory’s uncle and surrogate father (the young naturalist was an orphan), Bernard Journu-Auber (1745–1815), was one of the richest men in the country, and a close collaborator of General Bonaparte as Regent of the Central Bank of France, may explain why no one dared to attack a naturalist placed under such a tutelage. Even the serious accusation of desertion came to nothing: indeed, Journu-Auber even proposed that his prote´ge´ should be promoted to the rank of Captain for the services rendered to the State during the expedition he deserted. A final example, concerning an amateur naturalist well known in his time throughout Europe, and completely ignored by historians, will reinforce the point that during the Consulate and the Empire the danger of maintaining unsavoury philosophical or scientific tenets was inversely proportional to the social status of the proponent. Jean-Baptiste Fray-Fournier (1764–1835) was a surgeon and

26

P. Corsi

amateur naturalist who lost the use of his right hand and opted for a lucrative career as a purveyor for the army (Commissaire Ordonnateur des Guerres) and organizer of military hospitals for the Grande Armeé.27 He travelled and worked through several German States, and resided for sometime in Berlin, Magdeburg and Ulm, from where he engaged in correspondence with leading German naturalists. Fray’s passion, and in his mind his title to consideration, were his experiments on the spontaneous generation of organic molecules. He got Pierre Jean Georges Cabanis (1757–1808) interested in his work, and even performed at Arcueil, under the eyes of Claude Louis Berthollet (1748–1822) and his assistants. Fray, a believer and a Christian, was convinced that organic molecules were formed thanks to the action of solar rays, and they could combine to give birth to elementary forms of life. Once life started developing, everywhere in the world it would climb the ladder of complexity from monad to man. Though the process was the same everywhere on Earth, the end result (as well as the intermediate steps) was marked by the physicochemical peculiarities of the locality were the process started. Thus, he explained, on the top of the Pyrenees one can find trees that are specific to the locality, since they developed from spontaneous generations made up of basic molecules typical of the physico-chemical constitution of those mountains. Though Fray did not doubt that the process had been providentially designed by an all-benevolent creator, his account of the origin and development of life on Earth bore here and there close resemblance to points Delame´therie, Bory and other materialists advocated. Fray’s work attracted favourable attention in Germany. Top naturalists such as Friedrich Tiedemann (1781–1861), Johann Friedrich Meckel (1781–1833) and Wilhelm August Eberhard Lampadius (1772–1842) praised his work, and adapted it to their own views of the origin and development of life forms. In France, Antoine Desmoulins quoted with approval – without mentioning the name of Fray – the explanation for the peculiar flora and fauna showed by isolated geographical areas such as the picks of the Pyrenees, whereas during the 1820s Bory de SaintVincent and others denied that Fray had preceded them in elaborating the theory of the spontaneous generation of organic molecules. In the British Isles, Fray’s work was well known to John Barclay (1758–1826), a famous teacher of anatomy at Edinburgh, who in 1822 devoted a long chapter of his An Inquiry Into The Opinions, Ancient And Modern, Concerning Life And Organization to a refutation of the Frenchman’s work (whom he considered a better thinker than Erasmus Darwin), filled with quotations in French. Barclays even bothered to reproduce the paragraphs Cabanis devoted to the first experiments performed by Fray in the early 1800s.28 I do not need to expand upon the fact that in France no one appears to

27

Joe¨lle Jezierski, “De fleur et de sang. Parcours d’un herbier napoleónien”, in Machine a` feu. Revue du livre et de la lecture en Limousin, 25 (2007), pp.40–41 28 Jean-Baptiste Fray, Essai sur l’origine des corps organise´s et inorganise´s, et sur quelques pheńome`nes de physiologie animale et ve´ge´tale, Paris, Mme Ve Courcier, 1817. An earlier and shorter version of the work, Nouvelles expe´riences extraites d’un manuscrit qui a pour titre: essai sur l’origine des substances organiseés et inorganiseés had been published in Berlin, L. Quien,


27

have challenged Fray’s tenets or asked him to distance himself from current materialist and atheist explanations for the history of life on earth. His trusted role as a pillar of the medical services of the Grande Armeé acted as a very effective shield. What about the Restoration? After an initial tolerant attitude towards the freedom of the press and of opinion, successive ultra-monarchic administrations introduced increasingly restrictive measures. Censorship was exercised with the utmost severity on theatre productions, or on the teaching of history in schools preparing students for the Agre´gation.29 In 1825 an anti-blasphemy legislation was passed, so extreme that even a famous writer and right wing politician such as François-Rene´ de Chateaubriand (1768–1848) felt that Chares X had done what no King of France had ever dreamt of. One might expect scientific doctrines openly or implicitly favouring atheism and materialism to be repressed, denounced or at least censored, Lamarck’s in primis. Systematic perusal of periodicals, encyclopaedias, dictionaries and single works published during the Restoration reveal that this was not the case. Conservative writers, including Cuvier, denounced as leaning towards pantheism, if not atheism, Lamarckian transformism, the doctrine of the unity of composition prevailing – according to Geoffroy Saint-Hilaire and his allies – throughout the animal and vegetable kingdoms, or the theory of embryonic recapitulation, according to which the phases of development of the embryo summed up the major steps in the development of life throughout the history of the Earth. Cuvier’s or Virey’s strictures only added to the success of “dangerous” doctrines with the reading public. From the pages of the internationally successful Dictionnaire classique d’histoire naturelle (which travelled with Darwin on the Beagle) he edited from 1822 to 1832, Bory de Saint-Vincent blasted against the Jesuits and the theory of the immortality of the soul, as well as against Cuvier’s conservatism, and extolled the virtues of Lamarck’s dedication to scientific truth and his colleague’s transformist doctrines. Bory vigorously campaigned in favour of polygenism, and his many works provided readers in Europe and the United States with accurate summaries of the various standpoints debated by French naturalists. He avoided mentioning, needless to say, that Lamarck believed in the unity of the human species. During the 1820s, the golden decade for Lamarck’s reputation in France and Europe, his doctrines were subjected to a variety of criticisms and only a few commentators insisted on the dangerous leaning of his teaching and theorizing. From Edinburgh to G€ ottingen, from Turin to Paris, it was common to pay homage to the old naturalist, who had left a monument of taxonomic achievement such as the Histoire naturelle des animaux sans verte`bres (7 vols., 1815–1822). The fact

and Paris, chez Nicolle, 1807. J. Barclay, An Inquiry Into The Opinions, Ancient And Modern, Concerning Life And Organization, Edinburgh, Bell and Bradfute, 1822, pp. 126–142; for the quotations from Cabanis, see pp. 127–128. 29 V. Granata, Politica del teatro e teatro della politica: censura, partiti e opinione pubblica a Parigi nel primo Ottocento, Milano, Unicopli, 2008.

28

P. Corsi

that Lamarck had become blind in 1818, and was now too sick to take part in public and scientific life, only added to the respect surrounding him during his last years. It is therefore clear that the assumption that Lamarck was isolated because of the religious and philosophical implications and consequences of his transformist doctrines has no foundation, and can be maintained only by ignoring the actual state of affairs in contemporary French and European scientific, political and cultural life.

3 Authors and Audiences Historians of science have traditionally shown a remarkable reluctance to accept the simple fact that at every given moment, the production of knowledge in a given society is as varied and diversified as the social, political or the religious scene. Since some individuals or groups of individuals appear to share our concept of science, or to approach it the most, they are taken as the only ones worth spending one’s time on. In doing so, a host of very interesting phenomena and events are completely ignored, even the ones that should appeal to the historians of the development of scientific “truth”. The case of Cuvier and his collaborators we mentioned above, or the composite nature of the natural history scene during the decades in which Lamarck acted his own life, deserve comment. I will deal in particular with selected features of debates within the medical profession; the latter’s changing political and intellectual allegiances; and the editorial ventures that represented the viewpoint of prominent factions within it. This will open up new and fascinating perspectives on the relationship between France and Germany during the first three decades of the nineteenth century, and on how Lamarck was read by different audiences. I hinted above that Cuvier was hardly in a position to dominate the natural history scene of his time, and experienced some difficulty even with his own collaborators, who depended on his good will more than anyone else. I will limit my comments to the two young authors who put Cuvier’s lectures on comparative anatomy in good form and published it. As is well known, Andre´ Marie Constant Dume´ril (1774–1860) took care of volumes 1 and 2 of the Leçons d’anatomie compareé (5 vols, 1800–1805), whereas his colleague Georges Louis Duvernoy (1777–1855) edited vols. 3–5. Dume´ril was undoubtedly the more independent of the two. A brilliant and precocious anatomist and medical lecturer, he arrived in Paris in 1800, and was immediately recruited by Cuvier to help him in all sorts of tasks, including the editing of his lectures. Dume´ril also engaged in teaching in the school of medicine of the capital that had taken the place of the abolished Medical Faculty. Duvernoy was coming from Montbe´liard, Cuvier’s home town, and was a distant relative of the naturalist. He was not as brilliant as Dume´ril, and his career was less conspicuous. Yet, even Duvernoy played a role we still know little about, and an important one, for that matter. As I pointed out years ago, his views of life


29

before entering Cuvier’s service were not as Cuvierian as one might assume. He saw an important role the medical philosopher could play when reflecting on the properties of living beings. He appeared to see life in terms of a fluid dynamics not dissimilar to the one Lamarck endorsed, though he rejected Delame´therie’s and Lamarck’s materialism. He also expanded upon the role of use and lack of use in shaping organs.30 We pointed out at the beginning of this article that the gathering of important collections in Paris forced naturalists from all over Europe to spend time in the French capital in order to take advantage of the unprecedented wealth of specimens. A young ambitious German anatomist, Johann Friedrich Meckel (1781–1833), spent the years 1804–1805 working in Cuvier’s laboratory. Back to Germany, Meckel translated the Leçons d’anatomie compareé before embarking on his own ambitious editorial projects. The role of Meckel in early nineteenth century German comparative anatomy and embryology is now well known, thanks to important studies published during the last 20 years.31 Yet, it is always assumed that during his stay in Paris the young anatomist worked with Cuvier. Now, this is again an easy and reasonable assumption, albeit one that it is difficult to prove. During the very early 1800s Cuvier was dividing his time between extensive travel through the French provinces, as Inspector General of higher education, and his growing political commitments. What we know for sure is that Meckel embarked upon the careful dissection of a limited number of human foetuses under the direct supervision, and collaboration, of Duvernoy.32 If we follow Duvernoy’s highly interesting narrative of events, published in 1849, we learn that Meckel worked on nine foetuses (a rare specimen to obtain even in Germany, though less so in Paris), and called upon Duvernoy to attest the reliability of his observations. Back home, in 1806 (in fact, already in 1805)

30

G.-L. Duvernoy, “Re´flexions sur les corps organises et les sciences dont ils sont l’objet”, in Magasin encyclope´dique, 5th year, vol. 3 (1799), pp. 459–474. See Corsi, The Age of Lamarck, pp. 75–76. 31 S. Gliboff, H.G. Bronn, Ernst Haeckel, and the Origins of German Darwinism: A Study in Translation and Transformation, Cambridge, MA, MIT Press, 2008. P. Hunemann, ed., Kant and the Philosophy of Biology, Rochester N.Y., University of Rochester Press, 2007. R. Richards, The Romantic Conception of Life: Science and Philosophy in the Age of Goethe, Chicago, University of Chicago Press, 2002. T. Lenoir, “Kant, Blumenbach, and Vital Materialism in German Biology”, in Isis, 71 (1980), pp. 77–108, and The Strategy of Life: Teleology and Mechanics in Nineteenth Century German Biology, Dordrecht, Reidel, 1982. T. Bach, Biologie und Philosophie bei C. F. Kielmeyer und F. W. J. Schelling, Stuttgart, Bad-Cannstatt, 2001. S. Schmitt, Les forces vitales et leur distribution dans la nature: un essai de “syste´matique physiologique”. Textes de Kielmeyer, Link et Oken traduits et commente´s, Paris, Brepols, 2007. 32 G.-L. Duvernoy, “Ovologie”, in Dictionnaire universel d’histoire naturelle, 9 (1849), pp. 281–353.

30

P. Corsi

Meckel published in German an essay, Fragments sur l’histoire du de´veloppement du foetus humain (we are of course following Duvernoy, who gave titles and texts in French), which ended with the conclusion: Je suis loin de regarder comme une ideé simplement ingeńieuse, celle de Kielmeyer, qui pense que le foetus humain passe par les divers degre´s de de´veloppement auxquels s’arreˆtent les animaux inferieurs. Un trop grand nombre de faits viennent le confirmer.33

One can therefore surmise that Meckel and Duvernoy discussed several issues in comparative anatomy and embryology, and it is possible that Meckel told Duvernoy of the many new ideas Carl Friedrich Kielmeyer (1765–1844), whom he had met and listened to, was expanding upon in his lectures and manuscripts. Of course, Cuvier too knew rather well what Kielmeyer was speculating upon. Yet, Duvernoy, who in his contributions to the Dictionnaire universel took pains even to show that Geoffroy Saint-Hilaire’s transcendental anatomy was in the last analysis due to Cuvier, is completely silent on the role his master played in directing Meckel’s work. Indeed, Cuvier does not appear to have played any role in Meckel’s research. As hinted above, the young German anatomist asked Duvernoy to witness his anatomies: he would not have missed the chance to say that the mentor’s role had been fulfilled by the already famous Cuvier, who by the way never paid much attention to embryology and deeply opposed the doctrine of embryologic recapitulation. It is possible that Antoine E´tienne Renaud Augustin Serres (1786–1868), the French main proponent of embryologic recapitulation, discussed recapitulation with Meckel, whom he met in 1805. Serres was a consumer of German works and became a keen reader and admirer of Lorenz Oken (1779–1851). The point which is important to stress is that Meckel became proficient in the French language and forged close personal links with several French colleagues, especially among the young aspiring naturalists and medical researchers courting notoriety through their anatomical research. Further research is required to reach a better understanding of the workings of Cuvier’s laboratory – and the laboratories of other Professors of the Museum – and the modalities of exchange with foreign visitors and researchers. Dume´ril was apparently more successful than Duvernoy in attracting young talent, though what follows only constitute the result of a first survey in need of more sustained research. A precocious anatomist and medical teacher at 19, Dume´ril, as we have already pointed out, reached Paris at the beginning of 1800. He was quickly noted by Cuvier, who associated him to his Leçons d’anatomie compareé, asked him to teach his class at the Ećole Centrale du Pantheón – one of the many jobs Cuvier was starting to hand out to faithful pupils – and in 1804 even

33

Duvernoy, “Ovologie”, p. 348. J. F. Meckel, “Fragmente aus der Entwicklungsgeschichte des menschlichen fœtus”, in Abhandlungen aus der menschlichen und vergleichenden Anatomie und Physiologie, Halle, Hemmerde und Schwetschke, 1805, pp. 277–381, now available at Edition Classic VDM Verlag Dr. Muller, 2007. See L. G€ obbel and R. Schultka, “Meckel the Younger and his Epistemology of Organic Form: Morphology in the pre-Gegenbaurian Age”, in Theory in Biosciences, 122 (2003), pp. 127–141.


31

passed on to him the task of writing a textbook on natural history he had no time to engage in, commissioned by the Government for the Lyceés. Dume´ril showed himself a reliable follower. In the textbook, he never mentioned Lamarck as an expert on invertebrates, but only Cuvier. All innovation in the classification of invertebrates was due to Cuvier’s anatomical research – which was to a great extent true- and Lamarck had played no role in reforming this important branch of zoology. Thus, no mention was made of the Syste`me des animaux sans verte`bres Lamarck had published in 1801, and his name appeared briefly in the text in the sections devoted to botany.34 Yet, if one lists the pupils Dume´ril himself took under his wings, and one considers what he himself published, one can see that he kept a good measure of independence from his master. In the very early 1800s he taught a young doctor, Jean Burdin, author of a Cours d’e´tudes me´dicales (1803) which contained the first published hint that the cranium could be seen as formed of expanded vertebrae.35 The three volumes work was translated into English and German within the year, even though we have no idea of who paid for this – possibly Henri de Saint-Simon (1760–1825), then still quite wealthy, and apparently close to Burdin. Early in 1808, Dume´ril himself proposed a vertebral theory of the cranium to the Institut, but was laughed down when someone in the audience uttered the ironic comment “here is the thinking vertebra”.36 He also endorsed the theory of the unity of plan prevailing throughout the animal kingdom, about which Cuvier was expressing growing reservations. Another pupil of Dume´ril was the irascible, highly original Antoine Desmoulins, who during the 1820s became a fierce and relentless opponent of Cuvier. It must be said that Desmoulins managed to quarrel with everybody in Paris, and even succeeded in making Geoffroy Saint-Hilaire defend Cuvier in print, so outrageous were his attacks against the famous naturalist. The last pupil Dume´ril coached and protected of whom I am aware is Antoine Jacques Louis Jourdan (1788–1848), an author deserving close attention. After studying medicine and opting at first for the lower qualification of surgeon, Jourdan left France to join the French army in Germany. He was mainly based in K€onigsberg and Berlin, and remained in the German states from 1808 until 1814 (with the exception of short stays in Paris, when training at the military hospital of Val de Graˆce). We have no idea of whether he had met Meckel in 1804–1805, when he was already a pupil of Dume´ril. What is certain is that he forged personal links

34 C. Dume´ril, Traite´ e´le´mentaire d’histoire naturelle, Paris, Crapelet, 1804, 2nd ed., 2 vols. Paris, De´terville, 1807. It is to be pointed out that in 1803 Dume´ril was appointed assistant to Lace´pe`de, who had taken up heavy political and administrative duties. 35 C. G. Carus, Traite e´le´mentaire d’anatomie compareé, suivi de recherches d’anatomie philosophique ou transcendante [. . .] traduit de l’Allemand par A.-J.-L. Jourdan, 3 vols., Paris et Londres, J.-B. Baillie`re, 1835. See pp. 4–5 for comments on Burdin, and on the contemporary development in France and Germany of ideas about the vertebrae composing the cranium. Carus also pointed out that Italy and England had contributed precious little to the “philosophical” developments in anatomy. 36 See Corsi, The Age of Lamarck, pp. 237–238.

32

P. Corsi

with many German anatomists and medical researchers, Meckel included, and started a systematic and gigantic project of translating German works into French. In his long career, he signed more than 70 major translations, including the works of Christian Friedrich Samuel Hahnemann (1755–1843), the founder of Homeopathy, a medical doctrine Jourdan endorsed and introduced to France. From the point of view of Cuvier, Jourdan showed a remarkable propensity to translate all the authors the great anatomist deeply disliked, Karl Friedrich Burdach (1776–1847) Gottfried Reinhold Treviranus (1776–1837) or Carl Gustav Carus (1789–1869) among others. Jourdan became a very active collaborator to the Dictionnaire des sciences me´dicales (60 vols. 1812–1822) a remarkable achievement of the French publishing industry. In 1818 he also became one of the chief authors and probably one of the editors of the Journal comple´mentaire du Dictionnaire des sciences me´dicales, a periodical that, as the title suggests, was designed to update the entries already published in the dictionary, as well as to provide welcome summaries of medical progress throughout Europe. It is significant that the editorial statement printed in issue n. 1. (signed by the publishers, but bearing clear marks of Jourdan’s style) listed 30 medical periodicals published in German, 6 in Italian, 5 in English and 1 in Dutch. Last but not least, Jourdan and the Journal comple´mentaire paid particular attention to Meckel and his innovative, systematic and truly impressive attempt to unite the study of comparative embryology and the study of comparative anatomy. No polemical hint was made – at least until the mid-1820s – but medical people well understood the meaning of the translation campaign from German and the policy pursued by the very successful Journal comple´mentaire and other medical publications The fact is that several representatives of the medical profession did not like Cuvier’s attempt to establish his own superiority in comparative anatomy and human anatomy. Many openly extolled the work of Marie François Xavier Bichat (1771–1802), the true reformer of French anatomical studies: no need to add that, in their view, Cuvier was not. During the late 1810s, Geoffroy Saint-Hilaire early incursion in and statements on transcendental anatomy, supported by eminent representatives of the medical profession, such as Serres and members of the Socie´te´ d’anatomie, as well as Geoffroy’s work on teratology, were perceived as constituting a satisfactory vindication of the autonomy of medical research with respect to research conducted within natural history disciplines. An alliance could be forged with Geoffroy, because of his strong links with the medical profession, and his growing confrontation with Cuvier. Moreover, starting with the early-1820s, severe repressive measure against leading members of the medical community, including the then old and extremely respected Philippe Pinel (1745–1826), threw leaders of the profession and ranks and file doctors into determined opposition to the Government. Medical journals and encyclopaedias, pamphlets and reports of meetings of medical organizations joined naturalists such as Geoffroy and his son Isidore or Bory de Saint Vincent in deprecating the poor state of natural sciences in France, mirroring the poor state of political freedoms. What about Lamarck in all this? And what about the larger picture of FrancoGerman scientific relationships during the early decades of the nineteenth century?


33

Jourdan expressed his admiration for Lamarck in a review of the Histoire naturelle des animaux sans verte`bres and in a long entry, “Germe”, devoted to the question of epigenesis and preformation, published in volume 18 of the Dictionnaire des sciences me´dicales.37 Contrary to his colleague Virey, who also wrote extensively for the dictionary and kept insisting that Lamarck’s doctrines lead to atheism, Jourdan summed up Lamarck’s main tenets with fairness and admiration, though he felt free to disagree on several key points. Jourdan, who had attended Lamarck’s lectures in 1806, was reading his teacher’s work with German eyes, so to speak. Thus, for instance, he argued that Lamarck’s insistence on the role of organic fluids and on fluid dynamics in explaining biological phenomena was very similar to the doctrines put forward by Johann Christian Reil (1759–1813), the founder of the famous Archiv f€ ur die Physiologie (1796–1815).38 Jourdan’s account of the doctrine of spontaneous generation proposed by his former teacher Lamarck correctly included reference to the different origins of the plant and animal kingdoms, and possibly of several branches of main types of animal organization (p. 161). His interpretation of the progress of organization made no reference to the “tendency” of life to develop more complex anatomical and functional structures. Jourdan rightly stressed that, according to Lamarck, from time to time the dynamic interaction between the organism and the environment required a change in the distribution pattern of fluids and nutrients, thereby favouring those parts that were solicited by a change in the habits of animals. In its turn, the change of habits was the consequence of a change in the physical or biological environment. More diversified and complex distribution channels for the fluids also implied a more specialized, and in the end more rapid circulation. The nervous system in humans constituted the best example of extremely fast movements of fluids inside a very sophisticated network of nervous fibres (pp. 167–180). Thus, the only “progressive” change in living bodies was constituted by the inevitable increase of the speed at which fluids moved within organisms, due to the specialization and refinement of conveying networks and ultimately of the fluids themselves. This did not, however, determine the way in which the organism was going to develop, since the creation of new organs depended on the actual circumstances in which animals found themselves and the actual challenges they had to face (pp. 163–164). Jourdan was not a convert, however. He expressed his conviction that the species barrier could not be overcome. Advanced experiments in domestication showed that even though much could be achieved by breeders, never a zebra had become a horse, he ironically concluded.

37

A.-J.-L. Jourdan, “Histoire naturelle des animaux sans verte`bres”, in Journal universel des sciences me´dicales, 2 (1816), pp. 145–181, and “Germe”, Dictionnaire des sciences me´dicales, 18 (1817), pp. 226–277. 38 Jourdan devoted a long article to the career and doctrines of Reil, again pointing out the similarities with Lamarck, “Litte´rature me´dicale allemande. Sur la connaissances et le traitement des fie`vres, par Jean-Chre´tien Reil”, in Journal universel des sciences me´dicales, 2 (1816), pp. 217–239.

34

P. Corsi

The entry in the medical dictionary, published a few months after the review we have alluded to, adds interesting dimensions to Jourdan’s attitude towards Lamarck. As in his review of the Histoire naturelle, the tone was respectful and sympathetic. Lamarck was to Jourdan one of the chief supporters of epigenesis, one who had convincingly shown the weakness of the preformist doctrine. Jourdan summarized with favour the theories that saw embryos and individual adults develop thanks to the addition of parts made possible by nutrition or produced thanks to environmental chemical and physical agents. Jourdan stressed that both preformism and epigenesis impinged upon our conception of the origin and the development of animal and plant life on Earth. Whereas preformists tended to embrace a strong or a weak version of creationism (all germs of all animals were created at the beginning of time, or successive creations of new germs occurred to fill gaps and losses), the followers of epigenesis were open to the idea that organisms were formed in succession through endless ages and endlessly changing environments. Lamarck, according to Jourdan, was the most coherent representative of the latter view.39 Once again, Jourdan was not a convert. His grasp of the niceties and complexities of the Lamarckian theoretical corpus is often well above what historians and other commentators have customarily said of Lamarck. Yet, he was not convinced that use and lack of use, and more generally the dynamic interaction between organisms and their environment was sufficient to explain macro-evolution. The Lamarckian mechanism accounted for the fixation of varieties into good species, perhaps for the production of new genera, but could not explain the emergence of new and more complex anatomical and functional structures. For this, one had to call upon the still unknown laws of development, at the level of the embryo, as well as at the level of the history of life on earth. In later years, Jourdan agreed with Meckel, Tiedemann, and his colleague Serres, that the development of the embryo showed the steps life had to climb in order to produce increasingly perfect beings. Once life was created, indeed, as Lamarck had pointed out, once several forms of spontaneous generation had appeared, each endowed with its own specific structural properties, each form could climb only according to the potential for growth its structure allowed. The laws of development were the key factor, both in ontogeny and in phylogeny. Lamarckian mechanisms only explained how birds adapted to all the environments they were found in, not how the anatomical and functional type “bird” had originated, or, better, had developed from less complex vertebrates. Jourdan commented on Lamarck’s ideas on several occasions, and always with the utmost respect. To him, as well as to Bory or Geoffroy, Lamarck deserved the full respect of the scientific community. He had dared to be wrong, whereas Cuvier simply censored other people’s ideas. And he had left a scientific legacy which Cuvier’s compilations could never match. There is of course no space to analyse the attitudes of other members of the medical community towards Lamarck – authors

39

A.-J.-L. Jourdan, “Germe”, Dictionnaire des sciences me´dicales, 18 (1817), pp. 226–277.


35

such as Nicolas Philibert Adelon (1782–1862), for instance, who wrote one of the rare reviews of Lamarck’s last work, the Syste`me analytique des connaissances positives de l’homme (1820), and kept referring to Lamarck in every successive edition of his successful medical textbook.40 It is by now abundantly clear that the restriction of the analysis of the reception of Lamarck’s doctrines to what Cuvier or a handful of naturalists had to say seriously distorts our understanding of debates on the life sciences during the early decades of the nineteenth century. Not only the vast majority of practitioners of natural history and authors of natural history publications have been denied any hearing, but the vociferous and politically very active population of medical writers and practitioners has been completely ignored. As far as France is concerned, it is not uninteresting to mention that among the most prolific medical authors of the late 1810s and the 1820s a good number were former medical officers of the Napoleonic armies, left without pay, as all former army senior staff had been, by a vindictive decree of the Restoration Government. Many wrote as much as possible simply to implement their income. Their economic needs, their need for recognition and their wounded pride contributed to create an explosive mixture that added to the mounting tension leading to the July 1830 revolution. It is not by chance that after July 1830 many medical radicals of the 1820s returned to their professional occupations, lowered their tone and relented their assaults against “official” science. Many journals, such as the Journal comple´mentaire, even abandoned their campaign in favour of German medicine and anatomy. It was time to stop imitating foreigners. True, other journals did take up the fight, and dictionaries of the 1830s, 1840s and 1850s kept discussing transcendental anatomy or Lamarckian doctrines. Simply, those discussions had lost the political pregnancy and urgency they had taken on during the 1820s. One final comment is called for. The question of the relationship between French medical authors and their German colleagues cannot be looked at as a parochial anecdote or a minor episode within the larger picture of European debates on life of the early nineteenth century. Several historians have recently argued for the importance of German anatomical, embryological and medical doctrines for the debates on the life sciences that marked the period 1820–1850 in Scotland and England, for instance, and for the formation of Charles Darwin’s view of nature and of life.41 It is perhaps useful to recollect that Jourdan’s translations of Meckel, Tiedemann, Carus, Burdach, Treviranus were in fact destined to the British book trade as well

40

N. P. Adelon, “Syste`me analytique”, in Revue encyclope´dique, 9 (1821), pp. 257–267, and Physiologie de l’homme, 4 vols., Paris, Compe`re jeune, 1823–1824, see vol. 4, pp. 3–4, 103–104, 114–115, 232, for favorable summaries of Lamarck’s ideas. Adelon was one of the editors of the Dictionnaire des sciences me´dicales. 41 See R. Richards, The Romantic Conception of Life: Science and Philosophy in the Age of Goethe, Chicago, University of Chicago Press, 2002, for an authoritative presentation of this argument and the relevant bibliography. See also Philip F. Rehbock, The philosophical naturalists: themes in early nineteenth-century British biology, Madison, University of Wisconsin Press, 1983.

36

P. Corsi

as to the French one. It was the entrepreneurial genius of Jean-Baptiste Marie Baillie`re (1797–1885) that saw the opportunity for profit to be gained in England, and from his shop in Regent Street the French translations of German works were sold to private and public medical libraries. More than that: the English language edition of Tiedemann’s seminal work Anatomie du cerveau: contenant l’histoire de son de´veloppement dans le foetus was undertaken from the French translation, not from the German original.42 The introduction by Jourdan, as well as his annotations to the text, was probably considered a kind of added value, though one cannot exclude that during the 1820s and the 1830s it was easier to find in London a translator from the French language rather than from the German one. Meckel’s works circulated in England in the French editions, rarely in the original German. Even famous anatomists who knew German, such as the polyglot Robert Edmund Grant (1793–1874), or Robert Knox (1791–1861), owned Meckel in the French edition, not the German one. An English language edition of the handbook of anatomy by Meckel was nevertheless published in the United States from the French edition edited by Jourdan, though the translator informed his readers that he had consulted a German speaking medical man, in order to correct a few mistakes and inaccuracies present in the French edition.43 The set of easy assumptions concerning the place and reputation of Lamarck within the French natural history community of the early decades of the nineteenth century has traditionally acted as true Idola tribus, preventing research and limiting in considerable ways our understanding of the complex intellectual, social and political dynamics of contemporary natural history practices and publishing. The almost total lack of interest for the state of affairs in the publishing industry of the period under consideration, and the total lack of interest for what books, dictionaries, encyclopaedias actually said, has made us blind to major debates of great significance for the history of the life sciences at European level during the early decades of the nineteenth century. The reconstruction of the ways in which Lamarck was read, admired, criticized or denounced cannot be undertaken without reconstructing the actual articulations of the contemporary natural history and medical scene, in all its institutional, social and political dimensions.

42

The French translation of Tiedemann appeared in 1823; the English language edition, The anatomy of the fœtal brain: with a comparative exposition of its structure in animals [. . .] Translated from the French of A. J. L. Jourdan, by William Bennett, M. D., appeared in Edinburgh in 1826, J. Carfrae and Son. 43 Manual of general, descriptive, and pathological anatomy, by J. F. Meckel [. . .] Translated from the German into French, with additions and notes, by A. J.L. Jourdan and G. Breschet. Translated from the French, with notes, by A. Sidney Doane, 3 vols., Philadelphia, Carey & Lea, 1832. Doane, a graduate from Harvard University, had studied in Paris during 1830–1832. He translated several French medical textbooks and specialized monographs into English.


37

References 1. Adelon NP (1821) Syste`me analytique des connaissances positives de l’homme. Revue encyclope´dique 9:257–267 2. Adelon NP (1823–1824) Physiologie de l’homme, vols 4 . Compe`re jeune, Paris 3. Bach T (2001) Biologie und Philosophie bei C. F. Kielmeyer und F. W. J. Schelling. BadCannstatt, Stuttgart 4. Bange R (1994) Les ressources de l’e´tat civil parisien pour l’histoire des sciences. L’exemple de Lamarck. Bulletin de la Socie´te´ d’histoire et d’e´piste´mologie des sciences de la vie 1:30–41 5. Barclay J (1822) An inquiry into the opinions ancient and modern concerning life and organization. Bell and Bradfute, Edinburgh 6. Blagdon FW (1803) Paris as it was and as it is, 2 vols. C. and R. Baldwin, London 7. Blainville HD (1817) Notice historique sur la vie et les ećrits de J.-C. Delame´therie. Journal de Physique 85:78–107 8. Blainville HD (1832) Observations sur la chaire d’histoire naturelle du Colle`ge de France. Paris 9. Bory Saint de Vincent JB (1823) Matie`re verte. Dictionnaire des sciences naturelles 29:314–336 10. Bourdon I (1837) Lamarck. Dictionnaire de la conversation et de la lecture 34:265–269 11. Browne J (1995–2002) Charles Darwin, 2 vols. Jonathan Cape, London 12. Burkhardt RW (1995) The spirit of system: Lamarck and evolutionary biology. Harvard University Press, Cambridge, MA, 1977 paperback ed 13. Burkhardt RW (2007) The leopard in the garden: life in close quarters at the Museum d’Histoire Naturelle. Isis 98:675–694 14. Carus CG (1835) Traite e´le´mentaire d’anatomie compareé suivi de recherches d’anatomie philosophique ou transcendante [. . .] traduit de l’Allemand par AJL Jourdan, 3 vols. Paris et Londres JB Baillie`re 15. Corsi P (2005) After the revolution: scientific language and French politics 1795–1802. In: Pelling M, Mandelbrote S (eds) The practice of reform in health medicine and science 1500–2000. Ashgate, Aldershot, pp 223–245 16. Corsi P et al (2006) Lamarck philosophe de la nature. PUF, Paris 17. Corsi P (2006) Biologie. In: Corsi P et al (eds) Lamarck Philosophe de la nature. PUF, Paris, pp 37–64 18. Coulmann JJ (1862–1869) Re´miniscences, 3 vols. Michel Le´vy fre`res, Paris 19. Cuvier G (1799) Extrait d’une Notice biographique sur Bruguie`re lue a la socie´te´ philomathique dans sa seánce geńe´rale du 30 nivoˆse an VII. Magasin encyclope´dique 5th year, 3, pp. 42–57 20. Cuvier G (1831–1833) E´loge de M. de Lamarck lu a` l’Acade´mie royale des sciences le 26 Novembre 1832. Me´moires de l’Acade´mie royale des sciences de l’Institut de France 13: i–xxx 21. Darwin C (1868) The variation of animals and plants under domestication, 2 vols. J. Murray, London 22. Daugeron B (2007) Apparition-Disparition des Nouveaux mondes en Histoire naturelle Enregistrement-Epuisement des collections scientifiques (1763–1830) Paris EHESS The`se de doctorat, 2 vols 23. Delame´therie JC (1793) Discours pre´liminaire. Journal de physique 42:3–34 24. Desmond A (1989) The politics of evolution. Morphology medicine and reform in radical London. University of Chicago Press, Chicago/London 25. Desmond A, Desmond A, Moore J (1991) Darwin. Michael Joseph, London 26. Desmoulins A (1826) Histoire naturelle des races humaines. Me´quignon-Marvis, Paris 27. Dume´ril C (1807) Traite´ e´le´mentaire d’histoire naturelle Paris Crapelet 1804, 2nd edn, 2 vols. De´terville, Paris 28. Duvernoy GL (1799) Re´flexions sur les corps organises et les sciences dont ils sont l’objet. Magasin encyclope´dique 5th year, 3: 459–474

38

P. Corsi

29. Duvernoy GL (1849) Ovologie. Dictionnaire universel d’histoire naturelle 9:281–353 30. Endersby J (2008) Imperial nature: Joseph Hooker and the practices of Victorian science. University of Chicago Press, Chicago/London 31. Ferrie`re H (2001) Bory de Saint-Vincent (1778–1846): naturaliste voyageur et militaire entre Re´volution et Monarchie de Juillet ; essai biographique. The`se de doctorat, 2 vols. Universite´ Paris 1 Pantheón-Sorbonne 32. Ferrie`re H (2009) Bory de Saint-Vincent l’e´volution d’un voyageur naturaliste. Syllepse, Paris 33. Fray JB (1817) Essai sur l’origine des corps organise´s et inorganise´s et sur quelques pheńome`nes de physiologie animale et ve´ge´tale. Mme Ve Courcier, Paris 34. Fray JB (1807) Nouvelles expe´riences extraites d’un manuscrit qui a pour titre: essai sur l’origine des substances organiseés et inorganiseés. Berlin L. Quien and Paris chez Nicolle 35. Gayon J (2006) Lamarck philosophe. In: Corsi P et al (eds) Lamarck philosophe de la nature. PUF, Paris, pp 9–35 36. Gliboff SHG (2008) Bronn Ernst Haeckel and the origins of German Darwinism: a study in translation and transformation. MIT Press, Cambridge, MA 37. G€obbel L, Schultka R (2003) Meckel the younger and his epistemology of organic form: morphology in the pre-Gegenbaurian age. Theory Biosci 122:127–141 38. Granata V (2008) Politica del teatro e teatro della politica: censura partiti e opinione pubblica a Parigi nel primo Ottocento. Unicopli, Milano 39. Hunemann P (2007) Kant and the philosophy of biology. University of Rochester Press, Rochester 40. Jezierski J (2007) De fleur et de sang’. Parcours d’un herbier napoleónien In Machine a` feu. Revue du livre et de la lecture en Limousin 25: 40–41 41. Jourdan AJL (1816) Histoire naturelle des animaux sans verte`bres [. . .]. Journal universel des sciences me´dicales 2:145–181 42. Jourdan AJL (1816) Litte´rature me´dicale allemande. Sur la connaissances et le traitement des fie`vres par Jean-Chre´tien Reil [. . .]. Journal universel des sciences me´dicales 2:217–239 43. Jourdan AJL (1817) Germe. Dictionnaire des sciences me´dicales 18:226–277 44. Lacour PY (2010) La Re´publique naturaliste. Les collections françaises d’histoire naturelle sous la Re´volution 1789–1804. Ph.D. Dissertation 2 vols. Florence European University Institute 45. Lenoir T (1980) Kant Blumenbach and vital materialism in German biology. Isis 71:77–108 46. Lenoir T (1982) The strategy of life: teleology and mechanics in nineteenth century German biology. Reidel, Dordrecht 47. Marchant L (1858) Lettres ine´dites de Georges Cuvier a C. H. Pfaff sur l’histoire naturelle la politique et la litte´rature. Victor Masson, Paris 48. Meckel JF (1805) Fragmente aus der Entwicklungsgeschichte des menschlichen fœtus In Abhandlungen aus der menschlichen und vergleichenden. Anatomie und Physiologie Halle Hemmerde und Schwetschke, pp. 277–381 49. Meckel JF (1832) Manual of general descriptive and pathological anatomy by J. F. Meckel [. . .] Translated from the German into French with additions and notes by AJL Jourdan and G Breschet. Translated from the French with notes by A Sidney Doane, 3 vols. Carey & Lea, Philadelphia 50. Millin AL (1792) Journal d’histoire naturelle. Magazin encyclope´dique 1(8):57–60 51. Outram D, Cuvier G (1984) Vocation science and authority in post-revolutionary France. Manchester University Press, Manchester 52. Raspail FV (1830) Coteries scientifiques. Annales sciences d’observation 3:151–159 53. Rehbock PF (1983) The philosophical naturalists: themes in early nineteenth-century British biology. University of Wisconsin Press, Madison 54. Richards R (2002) The romantic conception of life: science and philosophy in the age of Goethe. University of Chicago Press, Chicago 55. Schmitt S (2007) Les forces vitales et leur distribution dans la nature: un essai de “syste´matique physiologique”. Textes de Kielmeyer Link et Oken traduits et commente´s. Brepols, Paris


39

56. Secord J (2000) Victorian sensation: the extraordinary publication reception and secret authorship of vestiges of the natural history of creation. University of Chicago Press, Chicago/London 57. Sonnini de Manoncourt CNS (1798–1808) Histoire naturelle geńe´rale et particulie`re par Leclerc de Buffon. Nouvelle e´dition accompagneé de notes dans lesquelles les supple´mens sont inse´re´s dans le premier texte a` la place qui leur convient. L’on y a ajoute´ l’histoire naturelle des quadrupe`des et des oiseaux dećouverts depuis la mort de Buffon celle des reptiles des poissons des insectes et des vers; enfin l’histoire des plantes dont ce grand naturaliste n’a pas eu le temps de s’occuper. Ouvrage formant un cours complet d’Histoire naturelle. [. . .] 127 vols. F. Dufart, Paris, Year VII 58. Stendhal (1958) The life of Henry Brulard translated and with an introduction by J Stewart and Bert CJG. Knight, London 59. Sykes JAC (1906) France in eighteen hundred and two described in a series of contemporary letters by Henry Redhead Yorke. William Heinemann, London 60. Tiedemann F (1816) Anatomie und Bildungsgeschichte des Gehirns im Foetus des Menschen: nebst einer vergleichenden Darstellung des Hirnbaues in den Thieren N€urnberg Steinischen Buchhandlung 61. Tiedemann F (1823) Anatomie du cerveau: contenant l’histoire de son de´veloppement dans le foetus: avec une exposition comparative de sa structure dans les animaux; traduite de l’allemand . . . par AJL Jourdan. JB Baillie`re, Paris 62. Tiedemann F (1826) The anatomy of the foetal brain: with a comparative exposition of its structure in animals [. . .] Translated from the French of AJL Jourdan by William Bennett MD. To which are added some late observations on the influence of the sanguineous system over the development of the nervous system in general. Illustrated by fourteen engravings. J. Carfrae and Son, Edinburgh 63. Virey JJ (1816–19) Nouveau dictionnaire d’histoire naturelle appliqueé aux arts a` l’agriculture a` l’ećonomie rurale et domestique a` la me´decine etc. par une Socie´te´ de naturalistes et d’agriculteurs 1803–1804. 1st edn, 24 vols, Paris De´terville ; 2nd edn, 36 vols 64. Virey JJ (1816–19) Nouveau dictionnaire d’histoire naturelle appliqueé aux arts a` l’agriculture a` l’ećonomie rurale et domestique a` la me´decine etc. par une Socie´te´ de naturalistes et d’agriculteurs 1803–1804. 1st edn, 24 vols, Paris De´terville; 2nd edn, 36 vols, Paris De´terville 65. Yorke H (1804) Redhead letters from France in 1802, 2 vols. HD Symonds, London

.

Darwinism Past and Present: Is It Past Its “Sell-by” Date? Michael Ruse

Abstract The year 2009 was the 200th anniversary of the birth of the English naturalist Charles Darwin, and also the 150th anniversary of his great book, On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life. No one who takes science seriously would begrudge Darwin his fame, but there is a major question that is worth asking. Do we honor Darwin as an important figure in the history of science, but not necessarily as one whose thinking still speaks to us today? Or are there aspects of Darwinian thinking that are still important today? Is it possible, desirable indeed, to be a Darwinian in the sense found in the Origin?

1 Evolution as Fact I want to go right to the heart of the matter, asking whether in the Origin Darwin really made a case for evolution – for evolution through natural causes – and whether this was successful and lasting. Did Darwin in the Origin give us an argument to merit taking evolution to be factual, in any reasonable sense of the term? Did Darwin give an argument that is still central to discussions today? Did Darwin give an answer that should be compelling to reasonable people? My focus is more on the fact of evolution rather than its causes, in the Darwinian case rather than on natural selection, or what today is usually cashed out as differential reproduction. It is obvious, however, that although ideally one might like to separate questions about the fact of evolution from questions about the cause or mechanism of evolution, in practice this is not really possible. This is especially true in the case of the Origin, for Darwin so often runs the two together. And in truth, really one would not want to separate the questions entirely. If evolution did

M. Ruse (*) Department of Philosophy, Florida State University, Tallahassee, FL, USA e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_3, # Springer-Verlag Italia 2012

41

42

M. Ruse

occur (fact) then there must have been some reason why this happened (cause). Hence, although the focus here is more on fact than on cause, I do not take the discussion to be irrelevant to the significance of natural selection. In his Autobiography, written towards the end of his life, Darwin wrote of the Origin as containing “one long argument” ([6], p. 140). But what was this argument? Actually it came in several (at least three) parts. In a letter written a year or two after the Origin was first published, Darwin made explicit mention of his strategy: In fact the belief in natural selection must at present be grounded entirely on general considerations. (1) on its being a vera causa, from the struggle for existence; & the certain geological fact that species do somehow change (2) from the analogy of change under domestication by man’s selection. (3) & chiefly from this view connecting under an intelligible point of view a host of facts. (Letter to George Bentham, 22 May 1863 [7]- Vol. 11, p. 433)

Mainly because I and others have elsewhere discussed the first two parts at length, but also because Darwin (as in this letter) thinks the third part the most important, I am going to focus on “this view connecting under an intelligible point of view a host of facts.” But before I turn to the Origin, I want to set some background, asking about influences and the methodological authority to whom Darwin would have turned in making his case.

2 The Consilience of Inductions One authority above all stands out: William Whewell, formerly professor of mineralogy at the University of Cambridge, later professor of moral philosophy and Master of Trinity, writer of textbooks, authority on the tides, and above all for Darwin’s purposes a good friend and mentor and an expert on scientific methodology [30]. Darwin had known and respected Whewell when an undergraduate, he was much in Whewell’s company when he returned from the Beagle voyage (first directly in Cambridge and then in London through shared involvement in the Geological Society), and he read and knew of Whewell’s beliefs about methodology. He read twice in the year of publication [33] the three-volume History of the Inductive Sciences and he knew well the contents of the later (1840) two-volume Philosophy of the Inductive Sciences from having read a detailed review by the astronomer-philosopher John F. W. Herschel [18], author of influential discussions of scientific methodology [17], later noted by Darwin [5]. Whewell came through loud and clear on the issues worrying Darwin. Why should one accept a causal theory when one doesn’t see it in action – at least, one does not see it in action enough to do everything that is claimed? Whewell framed his inquiry in Newtonian terms. What would the great Sir Isaac Newton have done and said? Well, we know what he did. He explained everything in terms of the force of gravity. But precisely what Newton said about this was frankly ambiguous. Apparently we are to invoke true causes, verae causae. What is a vera causa? Here Newton was less than helpful, but Whewell was happy to help out.

Darwinism Past and Present: Is It Past Its “Sell-by” Date?

43

Clearly influenced by the rationalist strain in philosophy (Whewell was much enthused with the Kantian system), he argued that a true cause is something that comes at the center of what he called a “consilience of inductions” ([34], p. 2, p. 230). And what is this precisely? It is a situation where we have a hypothesis about a cause, which may well not be observed or encountered directly, but which explains a wide range of empirical facts. In other words, as in a detective story, the causal culprit is identified not through the act itself (which is generally unseen and unknown), but through the clues – the bloodstains, the footprints, the tobacco ash (a favorite of Sherlock Holmes), the broken alibi, the motive. The culprit did it, explains the clues, and conversely (in a feedback argument) the clues convict the culprit. Those of us who are professional philosophers of science know that this kind of argumentation – varieties of which have also gone under the name of “abduction,” the term of Charles Sanders Peirce [2], and “inference to the best explanation,” popularized by the late Peter Lipton [22] – has been discussed ad nauseam. Here, I am going to assume that even though there are debates about why it is a good form of explanation, it certainly can be a good form of explanation. It can properly convince you of the truth of the binding premise. Note that we are not now asking for logical necessity, and note that often supporters of this kind of explanation demand that (having made the argument) one look for fresh, hitherto-unknown evidence of its truth. Whewell was strong on this. A real consilience shows it worth by pointing to unknown facts, perhaps even totally unexpected facts, thus convincing that it is really about objective reality and not just an ad hoc construal to build a pretty picture. All of the clues point to one potential culprit and then you find that (as in The Hound of the Baskervilles) he is the unknown next-in-line to the family fortune. Now that’s convincing! The young Darwin heard all of this, took note, and put it into practice. Let us now run quickly through the Origin and show precisely how Darwin put his Whewellian methodology to work.

3 Darwin’s Argument The first part of the Origin sets the scene, introducing natural selection, in part (as Darwin said in his letter) through the analogy with artificial selection and in part (also in the letter) by deducing natural selection in its own right. There is also discussion of subsidiary issues like sexual selection and the ways in which evolution branches and lines go their different ways (what Darwin called the “principle of divergence”). Next come discussion of problems like heredity, all of which clears the way for the positive treatment that takes us through the main part of the work. In turn, we take up behavior or instinct, hybridism and the links and gaps between groups, paleontology and the fossil record, biogeography and the distribution of organisms, systematics, anatomy, embryology, and ending with a gasp at rudimentary organs.

44

M. Ruse

In the case of instinct we get the explanation through selection of a beautiful example of what Richard Dawkins [9] has called the “extended phenotype.” Why is it that honey bees build hexagonal spaces for their young? Why not squares or circles or whatever? Through a number of rather ingenious experiments (involving the use of colored wax to see exactly how and when the bees use their building materials) Darwin was able to show that this is the most efficient use of the wax and as strong as you are ever going to get. He also showed that this seems not to be something that arrived in one instant, but that less efficient insects suggest that this ability of the honey bees is something that developed gradually. Moving on to the fossil record, much of the time Darwin was on the defensive, trying to show why it is that there are so many gaps in the record. But then he started to make the positive points, for instance about the roughly progressive nature of the record, a clear indication of descent with modification (to use Darwin’s phrase for evolution). Darwin made much of the extent to which one finds earlier fossils in the record, fossils that look like the combination of very different extant organisms. Lying behind a discussion such as this was the kind of Germanic thinking that led the anatomist Richard Owen [27] to his archetypal theory, where organisms within a group (like vertebrates) are seen as modifications of a basic ground plan or archetype, what Stephen Jay Gould was to call a Bauplan [14]. For an idealist like Owen, there was considerable doubt as to whether the archetype was a real organism, but for Darwin it was always an ancestor. Biogeography was a winner for Darwin, since it was the denizens of the Galapagos that set him on the road to evolutionism. Of course, there had to be a lot of discussion about how organisms could cross large oceans – Darwin always favored rafts and like phenomena rather than now-vanished land bridges – but basically it was gravy all of the way, as Darwin showed how the oddities of geographical distribution fall away under the gaze of natural selection. The Galapagos naturally had a starring role, as did the fact that the organisms of islands tend to resemble their neighbors on local land masses rather than animals and plants on lands far away. Darwin moved on through the fields. Systematics makes sense because of common descent. Anatomy comes to life because of evolution through selection. Phenomena noted and mysterious since the time of Aristotle – the homologies (as Richard Owen labeled them) between animals of very different lifestyle – are truly inexplicable if one is thinking purely in terms of function. “What can be more curious than that the hand of a man, formed for grasping, that of a mole for digging, the leg of the horse, the paddle of the porpoise, and the wing of the bat, should all be constructed on the same pattern, and should include the same bones, in the same relative positions?” ([4], p. 434) But of course they make perfectly good sense within the Darwinian picture. “The explanation is manifest on the theory of the natural selection of successive slight modifications,—each modification being profitable in some way to the modified form, but often affecting by correlation of growth other parts of the organisation. In changes of this nature, there will be little or no tendency to modify the original pattern, or to transpose parts” (p. 435).


45

Embryology, as we draw to a close, was a particular point of triumph for Darwin, and I suspect may have been a case where Darwin thought he was going beyond his original consilience and turning up new confirmatory information of a kind that was unexpected. Everyone knew that the embryos of organisms very different – human and chick – frequently look very similar. How can this be? Descent with modification, obviously. But then Darwin went into detail, showing how selection and his analogy from the world of breeding can provide real insight. The Darwinian argument is that adults have been torn apart by selection in the struggle for existence. But the young, by and large, are protected from the struggle, so there is no reason to expect them made different by selection. Turning to the domestic world, Darwin hypothesized that since breeders are generally interested only in the adults, we should find the young are far less different than their grown parents. Checking on horses – carthorses versus race horses – and dogs – greyhounds versus bulldogs – Darwin found his prediction to be correct, even though breeders had assured him that there was nothing to his supposition. And so (after some remarks about vestigial organs) we come to the end of the Origin, with that final flowery passage about entangled banks, singing birds, flitting insects, and crawling worms. “There is grandeur in this view of life, with its several powers, having been originally breathed into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being, evolved” (p. 490).

4 From Then to Now With the Origin now published and before us, I am going to jump 150 years. It is well known that, in its day, the Origin had mixed success [28]. Almost overnight, the world converted to evolution. Natural selection had to wait for acceptance. No one denied the mechanism outright, but few thought it as powerful as Darwin argued. It was in fact not until the 1930s, with the mathematical basis of Mendelian genetics well established, that people generally recognized the importance of selection and it started to take the place that it still has today. Without further ado, let us turn to the next question: Is the Darwinian consilience still active today and does it play the same role as it did in the Origin? Let us go once again through the range of biological phenomena seeing if and how Darwinian ideas explain and are in turn given support. Let me say straight out, however, that if we find ourselves saying no more than was said 150 years ago, I shall be surprised and disappointed. As Thomas Kuhn [21], above all others, pointed out, good science is not static. It moves forward solving problems (Kuhn called them puzzles) while staying true to the basic ideas. The structure and the spirit may stay the same but if the content is unchanged then truly we have a problem. Even if Darwin was right, why should anyone care? At least, why should anyone care other than as a matter of historical interest?

46

M. Ruse

5 The Consilience Today As with the discussion of the Origin, I am brushing right past such topics as artificial selection and the ways in which today’s biologists attempt to reproduce natural situations in the laboratory. Also, ways in which one might hope to find direct evidence of evolution in nature. I will focus exclusively on the argument across the whole of the life sciences. Start as before with instinct, by which Darwin very much meant social behavior. In the past half century, this whole topic has exploded outwards, in theory and in experiment and in study in nature. It has even been given its own name of “sociobiology.” Such evolutionary biologists as William D. Hamilton [15] and John Maynard Smith [23] in Britain and George C. Williams [35] and Robert Trivers [32] in America offered selection-based models explaining social behavior and following this theoretical work there was massive empirical attention. By the middle of the 1970s, the world’s leading ant biologist, Edward O. Wilson of Harvard, was able to write his magnificent overview Sociobiology: the New Synthesis [36] and Richard Dawkins of Oxford penned his popular account The Selfish Gene [8]. Take a first-class exemplar of this kind of work, Wilson’s own study of the leafcutting ants of the Amazon, the Atti. They have many castes – the large soldiers, the smaller foragers and then the leaf-cutters, the gardeners who tend the growing of fungi on the chewed-up leaves, the nursery workers who tend the young, and of course the massive queen. All told, the ant genus Atta has seven classes of workers. A key feature of Atta social life. . . is the close association of both polymorphism and polyethism with the utilization of fresh vegetation in fungus gardening. . . An additional but closely related major feature is the “assembly-line” processing of the vegetation, in which the medias cut the vegetation and then one group of ever smaller workers after another takes the material through a complete processing until, in the form of 2-mm-wide fragments of thoroughly chewed particles, it is inserted into the garden and sown with hyphae. ([37], p. 150)

Why the different castes and why the proportions? Wilson ran experiments (usually involving removing whole castes) to determine what is the most efficient way of using resources. If the ants want to get the most bang for the buck, less metaphorically get the greatest results in the sense of producing new, fertile, gene bearers for the minimum amount of effort, what role do the various castes play and is the proportion of one to another the most efficient? This kind of “optimality” thinking [26] – what would natural selection do to achieve the greatest adaptive efficiency – paid big dividends. “What A. sexdens has done is to commit the size classes that are energetically the most efficient, by both the criterion of the cost of construction of new workers. . . and the criterion of the cost of maintenance of workers.” I hardly need say that this is way beyond any kind of thinking that Darwin had, and yet in another sense is completely Darwinian. Most especially in making the division of labor absolutely crucial. Listen to Darwin in the Origin, speaking of sterile workers: “we can see how useful their production may have been to a social


47

community of insects, on the same principle that the division of labour is useful to civilised man” ([4], p. 241). The fossil record always fascinates. Again, in respects, we are far ahead of Darwin. For a start, we have absolute dates now. The beginning of the Cambrian 540 Mya, for instance. More than this, we have evidence of pre-Cambrian life [20]. To his embarrassment, Darwin had none and gave text-book examples of scientific adhockery – the fossils would be where the oceans are now and, even if we could drill, the weight above would have squashed them into non-being. Now we have a pretty good record of life from its beginnings and moreover this is life which starts simple and gets more complex, precisely as expected. We have lots more transitional fossils, most recently the fish-amphibian Tiktaalik from the upper reaches of snowy Canada. Or if you want a sequence, then the line leading up to humans is excellent [25]. Think about Lucy, Australopithecus afarensis, about 3.5 million years old, less than 4 ft tall, on her hind legs although not as good a walker as we (but probably a better climber), with a chimpanzee-size brain – 400 cc as opposed to our 1,200 cc [19]. Much contested is the question of whether Darwin was right in seeing (as he did) the history of life as a smooth process, leading from one form to another. For Darwin, this was part and parcel of his commitment to adaptation. Rapid changes would take organisms out of adaptive focus. He had no place for “hopeful monsters.” Famously, the late Stephen Jay Gould together with fellow paleontologist Niles Eldredge argued that the true course of history is much more one of stop and go – periods of relative evolutionary inaction (stasis) broken by times of rapid change [12]. Much ink has been spilt over this theory of “punctuated equilibrium,” including the question of how smooth a Darwinian gradual change must necessarily be. As with so many controversies, there is some truth in the Gould-Eldredge hypothesis but nothing like as much as was claimed at times by enthusiasts [31]. Rates of change do vary, but then what would you expect? At the micro-level, change is probably going to be pretty gradual, although precisely what one might mean by “pretty gradual” can be contested. Dimensions might be distorted drastically, very quickly, with major implications. Richard Dawkins’s [10] example is of a 747 Jumbo Jet being stretched, virtually overnight from the original form, to make for more passengers. We might get a change in (say) reptilian form pretty quickly this way. It is however unlikely that we would get something like the overnight change from reptile to bird. And of course the bird-reptile Archaeopteryx shows that this did not happen. (The Archaeopteryx fossils started to emerge in the early 1860s, and soon found their way into the Origin.) Biogeography was one of Darwin’s strongest supports for his theory and it continues to be so today. But here the changes have been truly staggering, because we are now in the era of plate tectonics, leading to continental drift. Although no one denies the powers of bird-dispersal and the like, there is no need of fabulous hypotheses – and especially not fabulous hypotheses about now-missing land links – because we now know that the continents move around the globe on massive plates, things which arise out of the earth, move in a stately fashion across the surface, and finally return into the bowels in an almost Wagnerian fashion. You can

48

M. Ruse

explain for instance why it is that the Permian reptile Lystrosaurus, a slug of a brute if ever there was one, can be found in Africa, India, and Antarctica. It did not go traveling under its own volition. It stayed where it was and let the moving plates do the hard work [29]. Systematics, morphology, embryology – they start to bring the consilience to a close. One could write full-length essays on each of these topics. Change and yet adaptation due to natural selection is the story. Systematics was transformed in the 1970s, thanks to the coming of cladistics, the system of classification based on the somewhat idealistic system of the German biologist Willi Hennig [16]. Although there were some (rather extreme devotees of the philosophy of Karl Popper) who questioned whether classifications need at all reflect history, generally it was (and still is) agreed that cladistic classification is firmly evolutionary. It is about paths or phylogenies. Less obvious, particularly at first, was whether it was always very Darwinian. For instance, change in a line without branching would not be (could not be) recorded. As methods have become more sophisticated and refined, however, particularly thanks to the coming of molecular techniques, it does seem that the gap between cladistic practices and results and Darwinian processes have come closer together. As it happens, like paleontology, morphology has been very controversial and for much the same or at least related reasons. Stephen Jay Gould argued that form, as in homology, is basic, and function, as in adaptation, comes afterwards. Certainly (according to him and co-writer Harvard geneticist Richard Lewontin) it does in many cases. Most particularly, because form puts its mark on organisms, much that we find has little or no relation to utility. Often, seemingly important adaptations are “spandrels,” that is to say by-products of other characteristics, which may or may not themselves be adaptive. Spandrels are the triangular spaces at the tops of columns in medieval buildings. Frequently, as in the church of San Marco in Venice – with beautiful decorations all over them. “The design is so elaborate, harmonious, and purposeful that we are tempted to view it as the starting point of any analysis, as the cause in some sense of the surrounding architecture.” But this is to reverse cause and effect. “The system begins with an architectural constraint: the necessary four spandrels and their tapering triangular form. They provide a space in which the mosaicist worked; they set the quadripartite symmetry of the dome above” ([14], p. 148). Warming to his theme, arguing that much of the living world is nonadaptive, Gould sneered that those who seek adaptation are too often like Dr Pangloss in Voltaire’s Candide, forever seeing value or use when there is none – “the best of all things in the best of all possible worlds.” According to Gould, Darwinians spin “just so” stories, at one with the fairy tales of Rudyard Kipling, who tells us that the elephant has a long trunk because a crocodile pulled it! Yet that the organic world is marked by adaptive complexity is, despite Gould’s rhetoric, simply a commonplace. Since Darwin, again and again the most outlandish feature has been shown tightly tied to reproductive utility. Take the triangular plates running along the back of the Stegosaurus, a monstrous dinosaur discovered in the American West in the decades after the Origin. What can they be for? Some have suggested sexual attraction; others have proposed that their utility comes as


49

weapons fighting or defence. The popular view today is that they are for temperature control, for heating and cooling [13]. The brute needed to warm up its blood first thing in the morning and then, at mid-day, particularly with the heat produced by its herbivorous diet, it needed to get rid of the heat. The plates are just like the fins one finding in electrical cooling towers, where they likewise are used for heat transference. Supporting the hypothesis, the fossil evidence is that the blood was moved from the main body (and back again) in just the efficient way one would suppose were heat transference the goal in mind. As sociobiology has transformed the study of instinct, so the new field of evolutionary-development has transformed embryology. The molecular biologists have moved in, giving new insights and empirical discoveries, and offering new theories. This is no bad thing, if only in the sense that the neo-Darwinian synthesis of the 1930s followed the population geneticists as regarding development as something of a black box – you have genes (genotypes) on the one side, and you have physical features (phenotypes) on the other side, and no one cared much about what went on in between. Pigs in, sausages out, and no questions please. Now this connection is brought into the sunlight, as biologists trace in detail the paths from the nucleic acids to the performing physical organisms. And some of the discoveries are simply staggering, again and again underlining the fact that the evolutionary consilience is so powerful in the ways that it points to discoveries altogether unimagined when the scientists started working and theorizing. A beautiful example centers on molecular homology. The late ornithologist and systematist, Ernst Mayr, writing in Mayr [24] about homology, having described it as the best of all kinds of evidence for evolution, warned non-biologists not to look for impossible isomorphisms between organisms as different as humans and fruitflies. You are not going to find them. One hopes that wherever he is, looking up or looking down, Mayr now celebrates the fact that at the molecular level there are the most incredible homologies between humans and fruitflies. It turns out that the genes that control development, the Hox genes, are nigh identical between the two organisms – and with many others too [3]. Does this threaten Darwinism? Is natural selection downgraded and the hunt on for a new, post-Darwinian theory? Why one should feel this need, why any of this should impact negatively on natural selection, is hard to imagine. We now know that organisms are built on the Lego principle – the same building blocks can make the White House or King Kong, a fruitfly or a human. But natural selection has no less of a role. Going back to earlier discussion, it is true that evo-devo shows that often you can get fantastic changes by altering what you have rather than by starting anew – the stretch 747 – but selection is no less important – if the plane does not fly, then it is of no use. From Thomas Henry Huxley on, there has been a downplaying of adaptation, especially by bench biologists who never see organisms alive and well, in their native habitats. But organisms do flourish, in their native habitats, and if biologists forget this fact, if they forget it is one thing to make an organism but then it must succeed in life’s struggles, they will never get the full story of evolution.

50

M. Ruse

6 Conclusions Darwinian evolution is a theory and a fact! We still have so identifiably the theory of the Origin. The consilience was crucial and effective back then; it is crucial and effective right now [11]. And yet, as in the best kind of science, the story is far richer than one of simple identity. The pre-Socratic philosopher Heraclitus said: “You cannot step into the same river twice.” Everything changes. The pre-Socratic philosopher Parmenides said: “How could what is perish? How could it have come to be? For if it came into being, it is not; nor is it if ever it is going to be.” Nothing changes. It was the genius of Plato to combine these two into one synthetic system and how right he was to do so. Everything has changed since the Origin. Nothing has stood still. Thank goodness! And yet nothing has changed. Darwin’s argument rules triumphant. Thank goodness! In the history of science as in the world of organisms, all is evolutionary – change and yet continuity and harking back to earlier successful forms. The analogy I like is with the people’s car, the Volkswagen, of late 1930s Germany. Today we have the Beetle, the Bug. Not one item of Dr Porsche’s brilliant design can be found in today’s car, and yet the Beetle is so obviously the Volkswagen of 70 years ago. I expect that in 50 years time we will still have the Beetle around. I expect that in 50 years or a 100 years we will still have the theory of the Origin around. Great, precisely because it does not stand still, but remakes itself and grows and changes by virtue of the fact that it gives such a terrific foundation. Is Darwinism past its sell-by date? Not by a long chalk yet!

References 1. Browne J (1995) Charles Darwin: voyaging. Volume 1 of a biography. Knopf, New York 2. Burch R (2006) Charles Sanders Peirce. In: Zalta EN (ed). Stanford encyclopedia of philosophy http://plato.stanford.edu/entries/peirce/ 3. Carroll SB, Grenier JK, Weatherbee SD (2001) From DNA to diversity: molecular genetics and the evolution of animal design. Blackwell, Oxford 4. Darwin C (1859) On the origin of species. John Murray, London 5. Darwin C (1868) The variation of animals and plants under domestication. John Murray, London 6. Darwin C (1958) The autobiography of Charles Darwin, 1809–1882. In: Barlow N (ed). Collins, London 7. Darwin C (1985) The correspondence of Charles Darwin. Cambridge University Press, Cambridge 8. Dawkins R (1976) The selfish gene. Oxford University Press, Oxford 9. Dawkins R (1982) The extended phenotype: the gene as the unit of selection. W.H. Freeman, Oxford 10. Dawkins R (1996) Climbing mount improbable. Norton, New York 11. Dawkins R (2009) The greatest show on earth: The evidence for evolution. Free Press, New York 12. Eldredge N, Gould SJ (1972) Punctuated equilibria: an alternative to phyletic gradualism. In: Schopf TJM (ed) Models in paleobiology. Freeman, Cooper, San Francisco, pp 82–115


51

13. Farlow JO, Thompson CV, Rosner DE (1976) Plates of the dinosaur stegosaurus: Forced convection heat loss fins? Science 192:1123–1125 14. Gould SJ, Lewontin RC (1979) The spandrels of San Marco and the Panglossian paradigm: A critique of the adaptationist programmeB. Proc R Soc Lond Ser B: Biol Sci 205:581–598 15. Hamilton WD (1964) The genetical evolution of social behaviour. J Theor Biol 7:1–52 16. Hennig W (1966) Phylogenetic systematics. University of Illinois Press, Urbana 17. Herschel JFW (1827) Light. In: Smedley E et al (eds) Encylopaedia metropolitana. J. Griffin, London 18. Herschel JFW (1841) Review of Whewell’s history and philosophy. Q Rev 135:177–238 19. Johanson DC (2009) Lucy australopithecus afarensis. In: Ruse M, Travis J (eds) Evolution: the first four billion years. Harvard University Press, Cambridge, MA, pp 691–697 20. Knoll A (2003) Life on a young planet: the first three billion years of evolution on earth. Princeton University Press, Princeton 21. Kuhn T (1962) The structure of scientific revolutions. University of Chicago Press, Chicago 22. Lipton P (1991) Inference to the best explanation. Routledge, London 23. Maynard Smith J (1982) Evolution and the theory of games. Cambridge University Press, Cambridge 24. Mayr E (1963) Animal species and evolution. Harvard University Press, Cambridge, MA 25. McHenry HM (2009) Human evolution. In: Ruse M, Travis J (eds) Evolution: the first four billion years. Harvard University Press, Cambridge, MA, pp 256–280 26. Oster G, Wilson EO (1978) Caste and ecology in the social insects. Princeton University Press, Princeton 27. Owen R (1848) On the archetype and homologies of the vertebrate skeleton. Voorst, London 28. Ruse M (1979) The Darwinian revolution: science red in tooth and claw. University of Chicago Press, Chicago 29. Ruse M (2008) Charles Darwin. Blackwell, Oxford 30. Ruse M (2009) William Whewell. In: Ruse M, Travis J (eds) Evolution: the first four billion years. Harvard University Press, Cambridge, MA, pp 913–919 31. Sepkoski D, Ruse M (eds) (2009) The paleobiological revolution. University of Chicago Press, Chicago 32. Trivers RL (1971) The evolution of reciprocal altruism. Q Rev Biol 46:35–57 33. Whewell W (1837) The history of the inductive sciences. Parker, London 34. Whewell W (1840) The philosophy of the inductive sciences. Parker, London 35. Williams GC (1966) Adaptation and natural selection. Princeton University Press, Princeton 36. Wilson EO (1975) Sociobiology: the new synthesis. Harvard University Press, Cambridge, MA 37. Wilson EO (1980) Caste and division of labour in leaf cutter ants (hymenoptera formicidae, Atta) 1. The overall pattern in atta sexdens. Behav Ecol Sociobiol 7:143–156

.

Evolutionary Theory and Philosophical Darwinism Paolo Casini

Abstract After the early reactions of the scientific community to Origin of the species, Darwin’s hypothesis was widely discussed by a growing number of professional historians and philosophers as well. This paper provides a short survey of historical research into the pre-Darwinian scenery of biological transformist intuitions of the so-called “forerunners”. This is an essential link to the following outline devoted to the divergent views of five relevant philosophical interpreters of the evolutionary theory: Spencer, Huxley, Haeckel, Nietzsche and Bergson. The intricacies of the Darwin-Spencer relationship are a necessary prelude to Huxley’s well-known Darwinian orthodoxy. In a way, Spencer’s monistic metaphysics was a no man’s land for friends and foes of Darwin’s Darwinism. Haeckel, naturalist and philosopher, translated Evolution into a systematic speculative Weltanschauung, while Nietzsche was first influenced by Darwinism and Spencerism and later rejected both. His Uebermensch myth was accompanied by an attempt to develop a biological-speculative basis for psychology. Bergson’s general critique of the experimental method and of the system of Spencer introduced his reinterpretation of evolution as a creative e´lan vital exclusively known through the inner perceptions of time, self-consciousness and intuition.

1 Philosophical Darwinism: A Short History Four decades of controversy concerning evolution had elapsed, and Darwin’s Darwinism was eventually accepted, when John Dewey, in his essay The Influence of Darwinism on Philosophy (1909), remarked: “The exact bearings upon philosophy of the new logical outlook are, of course, as yet, uncertain and inchoate. We live in the twilight of intellectual transition” [1]. The transition towards

P. Casini (*) Department of Philosophy, University “La Sapienza”, Roma, Italy e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_4, # Springer-Verlag Italia 2012

53

54

P. Casini

evolutionary logic, according to Dewey’s subtle analysis, expelled from biology, and from philosophy as well, all ideal archetypes, the concepts of design and finality, and destroyed the philosophic idol of eidoς (or species). But, if we consider the transition crisis from a historical viewpoint, its deeper roots should be mentioned. In fact, a variety of earlier, pre-Darwinian evolutionary intuitions had already undermined the Biblical myth of created species and the AristotelianScholastic taxonomy of class-genus-species became dubious. Geology and the study of fossil remains suggested alternative solutions of the “mystery of mysteries”. The great uniformitarian geologist Charles Lyell, a historian in his own right and one of Darwin’s authorities, was well aware of this historical background when he refuted Jean-Baptiste de Lamarck’s Philosophie Zoologique in volume II of his Principles of Geology (1832). Other contemporary historians tried to put the reverse question by asking: to what extent was Darwin influenced in his turn by the philosophers who had foreseen the problem of transformism with all their implications? Darwin wrote: “I was as ignorant as a pig about his subjects of history, politics and moral philosophy” [2]; but, as everybody knows, he was familiar with the works of the Reverend William Paley, William Herschel, William Whewell, Robert Malthus, James Mackintosh, Herbert Spencer, and a number of quotations in his youthful Notebooks show that he was impressed by certain themes of the empiricist philosophies of David Hume, John Stuart Mill, and “Monsieur Le Comte” [3]. In the Historical Sketch devoted to his precursors, he only mentioned a second-hand Aristotelian topic and then proceeded by quoting naturalists like Buffon, Lamarck, Geoffroy Saint-Hilaire, his grand-father Erasmus Darwin and 30 more pioneers of evolutionism, including Herbert Spencer [4]. Just after the publication of On the Origin of Species and of The Descent of Man, some scholars rediscovered the scattered intuitions of the Presocratics, the anti-creationist cosmogony contained in Book V of Lucretius’ De rerum natura, some writings of Eighteenth-century French materialists like Demaillet, Lamettrie, Maupertuis, Diderot and others [5]. The uninterrupted tradition of these old and recent authorities was considered as alternative to the myth of biblical creation, and they were read as anticipators of certain features of both Lamarckism and Darwinism. When two pioneering historians of biology, Emil Ra`dl and Adolf E. Nordenskj€old, outlined the genealogy of the sciences of life, the research concerning the forerunners of Darwin was a growing scholarly industry. By 1910 the Darwinian revolution was already considered as a significant chapter of the history of culture. The new archives of the history of ideas were opened by the comparative researches of Arthur Lovejoy, who brought into focus a full genealogy of pre-Darwinian intuitions in Maupertuis and Kant, Herder and Schopenhauer, Buffon and Lamarck. In the years 1909–1911 he studied old and new evolutionist cosmogonies ranging from the anonymous Vestiges of the Creation (1844) to L’e´volution creátrice (1907) of E´mile Bergson [6]. Moreover, in his classic The Great Chain of Being, Lovejoy outlined the course of the idea of the scala naturae in the history of western thought from Plato to Schelling [7]. His pioneering work was an outstanding contribution to the philosophical background and to the pre-history – or rather to the anti-history – of evolutionism. A rather

Evolutionary Theory and Philosophical Darwinism

55

different background was outlined by Ernst Cassirer who, a few years before his death, wrote the concluding chapters of his Erkenntnisproblem (1940), devoted to the Darwinian revolution [8]. In this book a short account of Darwin’s theory is preceded by an analysis of the concepts of “Form”, “Metamorphosis”, “Enwicklungsgeschichte”, which were commonplaces in the German philosophical culture of the eighteenth and nineteenth centuries. As a result, according to Cassirer, Darwin’s evolutionary theory appeared to stem from a composite background including Leibniz’ metaphysics of living organisms, the biological ideas of Caspar Wolff, Kant’s Kritik der Urteilskraft, the Romantic Naturphilosophie, the morphology of Goethe and von Baer. The role of the “idealistische Morphologie” in the growth of an historical view of Nature and Life seemed to be paramount for Cassirer (maybe he echoed Spencer), but he rejected correctly any comparison between Darwinism and Hegelian dialectics, a topic which had been discussed seriously, among others, by Friedrich Engels, Kuno Fischer, and Friedrich Nietzsche. Essentially, in Cassirer’s view, Darwin’s theory of descent was perfectly in line with some earlier intuitions of the Naturphilosophen. In a wider sense, Origins of Species deserved a place of high distinction for the epistemologists of the Marburg, neo-Kantian school. Paradoxically enough, Cassirer’s historical pedigree of Darwinism involves a curious blunder: in spite of Darwin’s general critique of special creations and of teleology, his “laws” of natural selection and of the survival of the fittest were interpreted by this historian, in the fullest sense, as “teleological principles”. Thus Darwin, as a theorist of the inherited successful variations favourable to the species, seemed to be a follower of “critical finalism”, in particular of Kant’s theory of “regulative” teleological judgement in biology as discussed in the Kritik der Urteilskraft. Finally, the complex history of preDarwinian, speculative evolutionism was fully treated by a Swiss biologist, E´mile Guyeńot, in his book devoted to the origins of L’ideé d’e´volution (1957), a landmark of L’e´volution de l’humanite´, the series directed by the historian Henri Berr [9].

2 Spencer and Darwin on Evolution These early surveys of the historical-philosophical aspects of the evolution theory seem to be obsolete today, in comparison to the work-in-progress of recent historians, whose researches proceed much more analytically into an open field, ignoring any disciplinary restriction and studying in depth the multifarious facets of the Darwinian revolution. One of the most interesting topics is the misleading relationship between Herbert Spencer, the philosopher of Evolution, and Charles Darwin, the naturalist and rigorous practitioner of the experimental method in biology. This topic was ambiguous enough to give way to most confusing philosophical, ethical, sociological variants of the evolution theory, obviously including the so-called “social Darwinism”. For example, Marwin Harris and Ernst Mayr formulated opposite views concerning the Darwin-Spencer relationship: Harris,

56

P. Casini

historian of anthropology, emphasized Spencer’s priority and originality, at least as a pioneer of the social sciences; Mayr, biologist and historian of biology, radically minimized his merits [10]. In the meantime, the controversial figure of Herbert Spencer, who was extremely popular until the end of the nineteenth century, re-emerged slowly from an enduring eclipse. In his youth, Herbert Spencer was deeply influenced by the peculiar scientific and naturalistic culture of the Derby Philosophical Society, where his father was a leading figure. He was educated as a mechanical engineer, but he was also an amateurish geologist, palaeontologist, and phrenologist. He was familiar with the eighteenth-century idea of progress in Nature pervading the proto-evolutionary views of Erasmus Darwin, naturalist and poet, author of Zoonomia, The Temple of Nature and The Botanic Garden, who enjoyed a high reputation among the founding father of the Derby provincial academy [11]. However, Spencer developed further his philosophical opinions as an autodidact in London, in the intellectual circle of the publisher John Chapman, the director of the radical “Westminster Review”. The growth of his reflections about society and politics was variously influenced by the opinions and theories of his closest friends: George Lewes, George Eliot, Harriet Martineau, and George Combes, who were strongly influenced in their turn by the Cours de philosophie positive of Auguste Comte and by the System of Logic of John Stuart Mill [12]. Spencer’s first books, Social Statics (1850) and the Principles of Psychology (first ed. 1852), beared the typical imprinting of this eclectic background, where also the roots of his much more ambitious “synthetic philosophy” are to be found. Lamarck’s evolutionary hypothesis was a most favourite theme of speculation for the young Spencer since the 1830s [11]. In his Autobiography he postponed in time his early initiation to the Philosophie Zoologique, affirming that he was first converted to the idea of the transformation of species in 1840, as a reaction against Charles Lyell’s critical exposition of it in the second volume of his Principles of Geology [12]. He generalized Lamarck’s transformation theory into a scheme of cosmic progress, including the nebular theory of the origins of the universe and some suggestions of the German Naturphilosophie, that he collected indirectly via Samuel Coleridge, Thomas Carlyle, and even an obscure Hegelian, Benjamin Heldenmayer. He was not among the enthusiast admirers of the Vestiges of Creation, but was initiated by the zoologist William Carpenter to Goethe’s theory of the metamorphosis of plants and to von Baer’s embryology. Spencer declared that he was deeply indebted to these naturalists: In respect to that progress which individual organisms display in the course of their evolution, this question has been answered by the Germans. The investigations of Wolff, Goethe, and von Baer, have established the truth that the series of changes gone through during the development of a seed into a tree, or an ovum into an animal, constitute an advance from homogeneity of structure to heterogeneity of structure. [13]

These last words, in all their vagueness, are one of Spencer’s earliest statements of the “development hypothesis”, the basic catchword of his system: in his views the homogeneity-heterogeneity scheme had the broad epistemological status of a


57

“law of Nature” (in Auguste Comte’s sense). In fact, it was the uncritical dogma he worked out for a lifetime in his “System of synthetic philosophy”, increasingly extending and applying it to all the sciences of nature, man and society. In his article The Development Hypothesis – first published in 1852 – and in several other essays written before 1857, Spencer not only outlined his theory of evolution, but discussed its physico-theological implications [14]. He rejected the current idea of “special creations” of the living beings and adopted Lamarck’s explanation of their variations under the “direct” pressure of the environment, in terms of adaptation and of an elementary process of survival of the fittest. The Principles of Psychology contained a most coherent application of the “Lamarckian” law to the evolution of human and animal mind. In receiving the first collection of Spencer’s papers [15], Darwin praised their “general argument”, but distinguished carefully his own professional approach to the problem of species in the forthcoming Origin: I have already read several of them [the Essays] with much interest. Your remarks on the general argument of the so-called Development Theory seem to me admirable. I am at present preparing an abstract of a larger work on the changes of species; but I treat the subject simply as a naturalist & not from a general point of view; otherwise, in my opinion, your argument could not have been improved on & might have been quoted by me with great advantage. [16]

This letter is usually quoted in order to confirm that Darwin was not indebted to Spencer. Reciprocally, Spencer was not indebted to Darwin: this is plainly proved by the chronology of his youthful Essays, and was openly declared for priority’s sake in his subsequent works and letters [17]. However, when Spencer read On the Origin of the Species, wrote to Darwin that the book obliged him to change his mind on a capital point: You have wrought a considerable modification in the views I held - While having the same general conception of the relation of species, genera, orders as gradually arising by differentiation & divergence like the branches of a tree & while regarding these cumulative modifications as wholly due to the influence of surrounding circumstances. I was under the erroneous impression that the sole cause was adaptation to changing conditions of existence brought about by habit, using the phrase conditions of existence in its widest sense as including climate, food, & contact with other organisms (for general statement of this view see Essay p. 41– 45) But you have convinced me that throughout a great proportion of cases, direct adaptation does not explain the facts, but that they are explained only by adaptation through Natural Selection. [18]

In spite of this afterthought, Spencer remained a staunch follower of Lamarck. He was always convinced that the vera causa of the modification of species was not to be found in inner or “indirect” factors, but in the “direct” impact of the environment. Darwin’s answer was magnanimous: “Of my numerous (private) critics, you are almost the only one who has put the philosophy of the argument, as it seems to me, in a fair way, as a hypothesis which explains several groups of facts” [19]. But 2 days later he revealed his wholly different feeling in a perhaps more sincere vein, rejecting Spencer’s verbiage: “I have just read his Essay on Population - he told Charles Lyell - in which he discusses life and publishes such dreadful hypothetical

58

P. Casini

rubbish on the nature of reproduction” [20]. When Spencer’s First Principles (1862) were published, Darwin was far from being fascinated by the grandiose project. He wrote to his close friend Hooker that the “great book” left him “greatly disappointed: all words and generalities . . . and I could grasp nothing clearly” [21]. Since 1858 Darwin had a changing opinion of Spencer and his philosophy; over the years his attitude swung between the extremes of praise and sarcasm. On the other side, Spencer defended the priority, chronological as well as theoretical, of his general law of development. He wrote to his father in 1864 that Darwin’s natural selection “is seen to be absorbed in the general theory of evolution as I am interpreting it” [22]. In his bulky Principles of Biology (1864) Spencer quoted throughout Dr [Erasmus] Darwin about living organisms, but made only a few references to the grandson Mr. [Charles] Darwin. As for the Darwinian law of natural selection, Spencer mentioned it only en passant. He reprinted fully in the Principles of Biology his Theory of Population, and in a footnote appended to this chapter he pointed up clearly the cleavage he posited between his own principle of the survival of the fittest and Darwin’s natural selection: This paragraph [. . .] shows how near one may be to a great generalization without seeing it. Though the process of natural selection is recognised, and though to it is ascribed a share in the evolution of a higher type; yet the conception must not be confounded with that article Mr Darwin has worked out with such wonderful skill. In the first place natural selection is here ascribed only as furthering direct adaptation – only as aiding progress by the preservation of the individuals in whom functionally-produced modifications have gone on most favourably. In the second place, there is no trace of the idea that natural selection, by co-operation with the cause assigned, or with other causes, produces divergences of structure; and of course, in the absence of this idea, there is no implication, even, that natural selection has anything to do with the origin of species. And in the third place, the all-important factor of variation – “spontaneous” or incidental as we may otherwise call it, is wholly ignored. [23]

Spencer’ s semantics is misleading: what he meant in speaking of “natural selection” was not exactly Darwin’s metaphor but, more or less, a new label for the same deterministic process he pretended to have described in terms of the evolution of all things “from homogeneity of structure to heterogeneity of structure”. Living organisms are subject to the laws of mechanics, physics, chemistry, thermodynamics; therefore they don’t possess any inner or “spontaneous” tendency to change. They progress only under the “direct” stimulus of the environment; consequently they inherit adaptive acquired characters. In the System, as far as the transmutation of species is concerned, there is no room for chance or random variations. Obviously, this means that Spencer did not accept the Darwinian mechanisms of sexual selection, gradual chance variation, and modification with descent, and that he had no doubt about the rigid speculative character of his own neo-Lamarckian biology. At least, he had no real concern for empirical evidence, and apparently underrated the radical divergence of his a priori method from Darwin’s experimental epistemology. But he did not hesitate to pretend that he shared with Darwin and Wallace the role of co-discoverer of organic evolution. Darwin’s reaction to Spencer’s speculative variant of evolutionary biology is recorded in another witty and biting letter to Hooker:


59

I have now read the last No. of H. Spencer [i.e. the Principles of Biology]. I do not know whether to think it better than the previous number, but it is wonderfully clever, and I dare say mostly true. I feel rather mean when I read him: I could bear, and rather enjoy feeling that he was twice as ingenious and clever as myself, but when I feel that he is about a dozen times my superior, even in the master art of wriggling, I feel aggrieved. If he had trained himself to observe more, even if at the expense, by the law of balancement, of some loss of thinking power, he would have been a wonderful man. [24]

We may conclude that the long-debated problem of reciprocal influence is, in a sense, an idle question. But this is not the end of the story. Rather surprisingly, in the fifth edition of Origin (1869), Spencer’s paramount formula of the “survival of the fittest” was accepted by Darwin pro domo sua: We have seen that man by selection can certainly produce great results [. . .] But Natural Selection, as we shall hereafter see, is a power incessantly ready for action, and is as immeasurably superior to mans feeble efforts, as the works of Nature are to those of Art. I have called this principle, by which each slight variation, if useful, is preserved, by the term Natural Selection, in order to mark its relation to mans power of selection. But the expression often used by Mr. Herbert Spencer of the Survival of the Fittest is more accurate, and is sometimes equally convenient. [25]

Furthermore, Darwin first introduced Spencer’s favourite term “evolution” in the 1872 edition of Origin and in Descent of Man. As it has been often remarked, these purely terminological or metaphorical changes did not alter substantially Darwin’s “long argument” in support of the variations of species by natural selection.

3 Chance and Determinism: Spencer, Darwin and Huxley Spencer’s theory of evolution was particularly at odds with Darwin’s theory of descent as far as the dilemma of chance and necessity was concerned. This highly significant topic deserves a further reflection, within the philosophical context of “Evolutionism”. Spencer’s faith in determinism was absolute. His Principles of Psychology – a book that Darwin praised at the end of the 6th edition of Origin and quoted in The Descent of Man -– were founded on a rigid deterministic basis. The analysis of the development of the psyche recapitulates the evolutionary process: in animals and humans alike, reflex action, instincts, memory, reason, are but consequential stages of a passive adaptation to the environment. This means, according to Spencer, that the mechanistic pattern, extended to human will and mind, destroys the illusion of free-will. The negation of chance and fortuitous events is, by definition, an obvious corollary of the general law of evolution from the homogeneous to the heterogeneous. The causal chain of psychical events is continuous and without breaks, and the Laws of Nature are no empirical or contingent rules, but normative, absolute, teleological principles. This means that in the System of Synthetic Philosophy the Evolution of Life is not an open-ended process. Notwithstanding his positivistic refusal of metaphysics and of final causes Spencer reaffirmed – paradoxically – that cosmic evolution aims to a supreme goal, and natural evolution culminates in social evolution: it is a work-in-progress pointing to

60

P. Casini

perfection [26]. Closing the circle, Spencer returned back to a semi-providential worldview. In his systematic style, he reproduced some features of the pre-Darwinian theologizing ideology of cosmic progress which had been shared by both Erasmus Darwin and Robert Chambers, the author the Victorian bestseller Vestiges of the Creation. Probably Charles Darwin had in mind all these aspects of the “Synthetic Philosophy” when, in an often-quoted passage of An Autobiography, he summarized in retrospect his mixed feelings concerning Spencer.1 Instead, Darwin’s methodical strategy in face of the chance/determinism dilemma was flexible and undogmatic. He remarked in Origin that when we speak of “chance variations” we should keep in mind that “this incorrect expression serves to acknowledge plainly our ignorance of the cause of each particular variation” [28]. Such a bracketing of the causal problem did not mean, however, a definitive suspension of judgement concerning the verae causae of the variation phenomena. Upon second thoughts Darwin worked out his pregnant metaphor of the skillful architect who realizes his project following a rational, “teleological” design by means of scattered chance-produced materials [29]. But in metaphysical sense the interaction of chance and necessity is a sort of quibble: “I feel most deeply – as he wrote to Asa Gray - that the whole subject is too profound for the human intellect”. For any attempt to solve the dilemma rises “a difficulty as insoluble as it is that of free will and predestination” [30]. In the Autobiography, recapitulating the “fluctuations” of his beliefs in creation, Darwin hints briefly to the skepticalmaterialistic doctrine of “blind chance or necessity” as opposed to his youthful belief in Paley’s physical theology: When thus reflecting I feel compelled to look to a First Cause having an intelligent mind in some degree analogous to that of man; and I deserve to be called a Theist. This conclusion was strong in my mind about the time, as far as I can remember, when I wrote the Origin of Species; and it is since that time that it has very gradually with many fluctuations become weaker. But then arises the doubt. Can the mind of man, which has, as I fully believe, been developed from a mind as low as that possessed by the lowest animal, be trusted when it draws such grand conclusions? May not these be the result of the connection between cause and effect which strikes us as a necessary one, but probably depends merely on inherited experience? [31]

1 “Herbert Spencer’s conversation seemed to me very interesting, but I did not like him particularly, and did not feel that I could easily have become intimate with him. I think that he was extremely egotistical. After reading any of his books, I generally feel enthusiastic admiration for his transcendent talents, and have often wondered whether in the distant future he would rank with such great men as Descartes, Leibnitz, etc., about whom, however, I know very little. Nevertheless I am not conscious of having profited in my own work by Spencer’s writings. His deductive manner of treating every subject is wholly opposed to my frame of mind. His conclusions never convince me: and over and over again I have said to myself, after reading one of his discussions,— ‘Here would be a fine subject for half-a-dozen years’ work.’ His fundamental generalisations (which have been compared in importance by some persons with Newton’s laws!)—which I daresay may be very valuable under a philosophical point of view, are of such a nature that they do not seem to me to be of any strictly scientific use. They partake more of the nature of definitions than of laws of nature. They do not aid one in predicting what will happen in any particular case. Anyhow they have not been of any use to me” [27].


61

The earliest philosophical vulgate of Evolutionism pieced together uncritically Darwin and Spencer. The initiates were troubled by the impossible task to conciliate their divergent views about the chance/determinism dilemma. During the last two decades of the nineteenth century the problem was discussed in the context of the dispute about the laws of nature by philosophers of science of various schools: critical positivists, materialists, contingentists, neo-idealists. This wider scene should be kept in mind in a brief survey of the solutions proposed by a few preeminent theorists of philosophical evolutionism who were at work between the end of the nineteenth and the beginning of the twentieth centuries, like Huxley and Haeckel, Nietzsche and Bergson. Thomas Huxley’s attitude was extremely significant. His own research as a marine experimental physiologist, his friendship with Spencer, his fierce rebuttal of Vestiges of the Creation, his pioneering and enthusiastic reception of Origins, followed by his stubborn militancy of “Darwin’s bulldog”, finally his straightforward rejection of Spencer’s synthetic philosophy and of the politics of “administrative nihilism”, seem to be as many uncertain steps into a contradictory path. And yet Huxley followed a coherent line of thought in his reflections concerning the freedom of the will, liberty and necessity, chance and determinism, particularly in his commentary of David Hume’s critical account of these problems [32]. According to Huxley’s mature epistemology, Darwin’s theory of descent was a successful working hypothesis, that should wait for proof by future experimental tests; but he was also convinced that no final evidence will ever be able to convert natural selection into a teleological, absolute, necessary and universal law of nature, taken in Spencer’s (and Kant’s) normative sense. In his book on Hume, Huxley fully agreed with his author’s conclusions about freedom and necessity, and the empirical connection of the cause-effect relationships. He extended Hume’s analysis to the phenomena and laws of living creatures. He thought the evolutionary biologist, like the astronomer and the physicist is, by definition, unable to transcend the contingent horizon of the phenomena, and to formulate laws of absolute certainty. Natural selection and the survival of the fittest are no exceptions to the probabilistic standards of experimental philosophy. A further inquiry into the “substance” of matter, living or non living – would also mean to absolutize, like Spencer did, the laws of nature, and in particular to relapse into the abstractions of Scholasticism and the traditional dichotomies of dualistic metaphysics: chance and finality, spirit and matter, creation and predestination. In short Huxley, a skeptical, “methodical” materialist, did reject systematic materialism, and even teleological evolutionism, as a dangerous basis of metaphysical dogmatizing. Darwin firmly excluded the final causes – Bacon’s “barren virgins” – from the transmutation of species. Huxley fully agreed, yet recognized that the descent of man assures to the human mind a dominant place in nature: but even mind, this culminating epiphenomenon of the transmutation process is subject, like any other phenomenon of nature, to the standard causal sequences. The theological illusion of freedom of the will stays and falls with the ideas of design and finality. But for Huxley this did not mean a rejection of the ethics of responsibility. On the contrary,

62

P. Casini

in his essay On Evolution and Ethics, without mentioning Spencer, Huxley energically reacted against the former’s postulate of a deterministic continuity – via the adaptation-in heritage scheme – of nature, ethics, and society. The ethics of sympathy which Darwin adopted in his analysis of the animal and human behaviour, enabled Huxley to counter the brutal struggle-for-life rule by the observable spontaneous growth of parental and social instincts, in man as well as in animal species. From the viewpoint of an anti-Spencerian and pro-Darwinian analysis of the descent of man “the ethical progress of society depends not on imitating the cosmic process. . . but in combating it” [33].

4 The Case of Ernst Haeckel The problem of chance was one of the main philosophical issues of the discussions concerning the evolutionary hypothesis in the United States and on the Continent. The German zoological, morphological, embryological, and anthropological culture was particularly receptive to darwinism thanks to the timely translation of Origins by Heinrich Bronn, and the immediate pro-Darwin support which was assured by the young naturalist Ernst Haeckel [34]. The speculations of Goethe, Schelling, Schopenhauer and the Romantic Naturphilosophie on living nature – animals and vegetables – undermined the purely taxonomic approach to the species by advancing new speculative hypotheses like Urph€ anomenon, Metamorphosis, Entwicklung. An obvious semantic shift occurred in the new usage of the last term: Bronn’s translation of Evolution by Entwickelung was, in a sense, the retranslation of a well-known German term that had been formulated by Ernst von Baer in 1825. Ever since his very first writings Haeckel was busy in founding the new evolutionary biology on the biogenetisches Grundgesetz, the supreme Law of recapitulation that he considered as the alpha and omega not only of organic morphology, but of natural history and of the physical world as a whole. If a single embryo recapitulates the transmutations of several preceding species and forms, the sequences of all the variations cannot be but intrinsically deterministic. The morphological changes of all living beings may be reduced to the universal scientific and philosophic postulate of the biogenetic law. Even human conscience, the culminating stage of the evolutionary process, is included in it. Haeckel agreed with the deterministic suggestion of Emile du Bois Reymond, who defined the freedom of the will one of Die Sieben Weltr€ athsel, the seven enigmas of the world. Haeckel too denied freewill, but believed that his own biogenetic Law was the only clue which could resolve this one as well as the other six Weltr€ athsel. In his several popular expositions of science von Haeckel outlined a growing encyclopedic repertory of the natural enigmas that had been already laid open. However, proceeding in the evolutionary chain from physical to chemical phenomena, from inert to living matter, from spontaneous generation to the tree of life, from mammalians to anthropogenesis, in order to explain all variation, heredity and adaptation phenomena von Haeckel introduced an ever-growing range of ad hoc laws,


63

never thought of by Darwin. Finally a lot of laws, under–laws, counter-laws, reduced the biogenetisches Grundgesetz into a fragmentary network of contingent rules, leaving considerable room for the random, unpredictable events of natural selection, much akin to Darwins’s chance variations. In this sense Haeckel, like Darwin, saw evolution as an open-ended process, and his researches helped in re-opening the problem still unknown “causes” of natural selection. Von Haeckel tried to extend even to the history of scientific ideas his biologisches Grundgesetz: he recapitulated, so to say, the history of the Abstammungslehre as a cumulative progression from Empedocles of Agrigentus to Giordano Bruno, from Goethe to Kant, from Oken and Lamarck up to Darwin, including the “great philosopher” Herbert Spencer. According to him, the whole story culminates in a new monistic and deterministic faith in Nature, based on the revival of a neo-Spinozistic and pantheistic phoenix through the Romantic Naturphilosophie. The Nat€ urliche Sch€ opfungsgeschichte (1868) was the propagandistic tool of a post-religious, eclectic and secular ideology: a kind of Wagnerian symphonic poem stuffed with striking dissonance and fascinating experimental suggestion. Haeckel had many admirers and many detractors, and helped in transforming Darwinism into a Weltanschauung which enjoyed an ephemeral world-reputation.

5 Romantic Evolutionists: Nietzsche and Bergson The evolutionary theories of both Darwin and Spencer, blended into one and the same ideology of Evolution – cosmological, biological, and social – influenced in depth the rhapsodic philosophizing of Friedrich Nietzsche by introducing into it a sign of contradiction. Ever since 1870 he assimilated the ideas of natural selection and survival of the fittest through the writings of some German commentators: David Strauss, Paul Reé, Karl Wilhelm N€ageli. Soon afterwards Nietzsche read extensively Spencer’s works and reacted against the philosopher’s sociological and ethical doctrines. He began by pointing out Spencer’s complicity with the average “gregarious morals” of the Christian tradition, or with certain features of Spinoza’s Ethics. In his devastating satire of the German “philistine” David Strauss, Nietzsche inveighs against the “whole descent of man from the earlier animal stage up to that of the cultivated philistine” [35]. Elsewhere he scoffs at the myth of the creation of Adam, and at the descent of human beings from such a sublime origin, now made futile by the forbidding image of “the most self-conscious ape grinding her teeth” [36]. Nietzsche accepted the descent of man from lower creatures as a “true but murderous theory”, and stressed in an “ultra-darwinist” mood the ancestral instincts, the aggressive pulsions, the war and competition among all living species. His personal conception of the struggle for life and of the survival of the fittest echoed the violent, lawless, hypothetical state of nature of Hobbes and Schopenhauer, and wholly denied the tribal and parental instincts shared by both man and animals, including the moral springs of sympathy and solidarity which

64

P. Casini

Darwin commented upon in The Descent of Man. Nietzsche eventually reproached the evolutionary naturalists with their inconsistency; in fact, they showed their incapability to foresee the moral and social consequences of the hypothesis. In several aphorisms of Daybreak (1880) e The Gay Science (1886) Nietzsche’s devastating analysis of false moral values is fully deterministic, and free will is denied, not only as a vain theological postulate, but as a self-deceptive mask, whereupon the traditional maxims of virtue and merit, individual responsibility and conscience are founded. On the other side, echoing in his own fashion the epistemological critique of the contemporary contingentist philosophy, Nietzsche justifies his skeptical attitude by radically denying any firm order in Nature, rejects the scientists’ faith in a naive principle of causality, and the postulate of necessary causation as well. Thus the experimental method, paradoxically including even the evolutionary hypothesis, was no more than a deceitful source of pseudo-truths. The Nietzsche scholars have traced in the minutest details his readings and the various stages of a tortuous itinerary culminating in the “Anti-Darwin” invectives of the years 1887–1889 [37]. The Zarathustra prophet not only blent together Darwin’s and Spencer’s ideas, but translated into commonsense psychological and moral terms – always within a neo-Lamarckian context – the pros and cons of the German evolutionary philosophers concerning topics like the instincts of survival, the adaptation to environment, the inheritage of useful variations, intraspecific competition and so on. As a result, Nietzsche sketched in his notebooks an idiosyncratic, non-scientific and deeply emotional version of individual and social € evolution, which eventually became a typical feature of the Ubermensch myth. In his Genealogy of Morals Nietzsche identified Spencer’s instinct of selfpreservation with the Spinozistic maxim of the perseveration of all things in their own being. He also criticized Spencer’s principles of adaptation and inheritance of the acquired characters, misunderstanding it – as it clearly appears from the context – as a mere “moral” or “psychological” tendency, a second-class activity, a mere capacity of “reacting”: This definition, however, fails to realise the real essence of life, its will to power. It fails to appreciate the paramount superiority enjoyed by those plastic forces of spontaneity, aggression, and encroachment, consequently the sovereign office of the highest functions in the organism itself [. . .] One remember Huxley’s reproach to Spencer of his “administrative nihilism” but it is a case of something much more than “the administration”. [38]

Clearly, Niezsche’s skepticism concerning the experimental method was the clue behind his bizarre translation of the biological laws, and of scientific research as well, into a misleading philosophical language, a rather Spencer-like by-product of Darwin’s working hypothesis. In so doing, Nietzsche tried to reaffirm the priority of pure speculation against the positive knowledge founded on the natural sciences. He even indulged in a kind of sociobiological explanation of the wrong face of “English Darwinism”: That today’s natural sciences have become so entangled with the Spinozistic dogma (most recently and crudely in Darwinism with its incredibly one-sided doctrine of “struggle for


65

existence”) is probably due to the descent of most natural scientists: in this regard they belong to “the people”, their ancestors were poor and lowly folks who knew all to intimately the difficulty of scraping it. English Darwinism exudes something like the stutty air of English overpopulation, like the small people’s smell of indigence and overcrowding. As a natural scientists, however, one should get out of one’s human corner; and in nature, is not distress that rules, but rather abundance, squandering – even to the point of absurdity. The struggle for existence is only an exception, a temporary restriction of the will to life; the great and small struggle revolves everywhere around preponderance, around growth and expansion and in accordance with the will to power which is simply the will to life. [39]

Nietzsche’s philosophical reflection fell into a kind of epistemological vacuum: his vain effort consisted in trying to refute the naturalistic theory of evolutionary change of living organisms through the process of adaptation, competition, natural selection etc., and in opposing to it the enthusiastic notion of the Wille zur Macht, a revised version of Schopenhauer’s metaphysical myth of the all-transcending Will. For Nietzsche, in other words, the Will to Power was the new fundamental Law of Nature superseding the pseudo-laws of positive science. Within the single organisms as well as in human society, the Will to Power is supposed to subdue to her peculiar ends the defects and the recessive involutive and degenerative characters. This is the anti-Darwinian kernel of Nietzsche’s “aristocratic” ideology condemning the human mass, obedient to the biological-spiritual stimulus of the Wille zur Macht, to be subservient to the prosperity of a higher and stronger human race [38]. The “Anti-Darwin” posthumous fragments and some aphorisms of the Twilight of the Idols summarize Nietzsche’s supreme grievances against the Darwin-Spencer doctrine. At the end of his parabola, Nietzsche exploited also some suggestions, found in F. A. Lange’s Geschichte des Materialismus and in the biological theories of Wihelm Roux, in order to support his voluntaristic metaphysics of the Will to Power, an Ersatz of natural selection. He pretended that this law represented the triumph of a non-Spencerian psychology or, more exactly, of the fr€ oliche Wissenschaft exalting an elementary force of nature ignored by positive science. The new myth, with its corollaries – the advent of the U˝bermensch, the eternal return – were the extreme, pathological manifestations, of a variant that Lovejoy defined romantic evolution. The visionary exaltation of the last Nietzsche announced, on the border of madness, the irrationalist and nihilist drive that was to degenerate from its psychological origins to the dead end of racism and political fanatism. A few years later Henri Bergson accepted the challenge of evolutionary biology on its own ground. He delineated a critique of positive science, attacking the experimental method from the viewpoint of his direct intuition. He developed a metaphysical approach quite different from what he called the traditional pseudoscience of cause, substance or essence. In his beginnings Bergson was imbued by Spencer’s synthetic philosophy, but he realized soon that “l’e´volutionnisme spence´rien e´tait a` peu pre`s a` refaire”. In his Essai sur les donneés imme´diates de la conscience he turned upside down both the principles of the positivist theory of knowledge, and the fundamentals of Kant’s Critique of Pure Reason, by introducing a radical dichotomy betwixt our “external” and “internal” perceptions

66

P. Casini

of time and space. He tried to demonstrate that the notions and measures of space and time, as currently used in the hard sciences, are mere abstractions. For physicists and astronomers deal with standard events which are regular and precisely predictable, apparently following uniform and deterministic laws. But this kind of “quantitative” knowledge ignores altogether the true essence of time, la dureé profonde. “Real time” may be discovered by way of direct intuition only, and this is the approach which unveils – beyond the fixed abstractions of the intellect – the “qualitative” flux of conscience. This uninterrupted sequence of individual, uncomparable, unique instants is the source of human psychology, of our free will, of the artist’s fancy, as well as of “open morality”, “open society”, mysticism and faith. If Spencer’s endeavour consisted in reducing biology, psychology and the social sciences to save the deterministic laws of mechanics and physics, on the contrary the job of Bergson’s Introduction a` la me´taphysique was to clear the way for a complete redefinition of the evolutionary laws of nature, beyond and outside the space-time framework of classical mechanics. The aim of pure philosophical intuition was to dig into the sources of the spontaneous flux of creative energy, l’e´lan vital. The immediate perception of the most shifty instants, past and present, of self-consciousness was instrumental even in penetrating from the inside the growing sequences of the phenomena of organic life and the evolutionary process of living species. In Bergson’s view, all the gaps of the evolutionary doctrine of Spencer, Darwin and their followers might be filled, all the problems of the ongoing experimental research might be resolved from the viewpoint of the creative flux of duration. Bergson’s main endeavour in his L’e´volution creátrice (1907) consisted in a painstaking, systematic analysis of the various theories discussed at that time among neo-Darwinian and neo-Lamarckian biologists concerning the “true causes” of variation, natural selection, inheritance of characters, and in re-examining thoroughly the old dilemma of chance and deterministic laws. Bergson put on one and the same level both traditional kinds of absolute determinism: the theological doctrines of providential design, and the mechanical-materialistic axioms of nature’s necessary laws. Both represented in his view a closed project, and the arbitrary projection into nature of our own abstract, anthropomorphic so-called “categories”. But finality and necessity are not forms given a priori to the trascendental ego, in Kant’s sense; they are rather by-products of our practical action, artificial schemes of our own skills. Bergson, aiming to a third solution, insisted on the creative power of nature, depending on “une cause d’ordre psychologique. . . l’e´lan originel de la vie” [40]. Thus Bergson returned, by begging the question, to his starting point, the metaphysical distinctions between time and duration, abstract and real, intellect and mind. He claimed he had based on such a foundation “une ideé plus compre´hensive, quoique par la` meˆme plus vague, du processus e´volutif”. The belief in the firm existence of the fixed, static forms of the zoological taxonomies, created or uncreated, is a mere illusion, equally shared by materialists and creationists. If we are able to uproot this prejudice, our conscience is able to oppose to the phantom of passive, outside matter his own active


67

energy, that is a whole cosmogony in motion “car l’univers n’est pas fait, mais se fait sans cesse. . . La conscience est essentiellement libre, elle est la liberte´ meme” [40]. Duration, spontaneity, free will, conscience, evolution – the catchwords of Bergson’s mystic vitalism – were opposed by a whole generation of philosophers to the positivistic faith in “science”. Thus a “philosophical” variant of the evolutionary hypothesis achieved a paradoxical task: Bergson’s speculation seemed to have digested and de-materialized the Darwin-Spencer vulgate of “evolution”. As Dewey wisely commented, “the exact bearings upon philosophy of the new logical outlook are, of course, as yet, uncertain and inchoate” [1]. He was perfectly right: the “twilight of intellectual transition” engendered not only a new science of nature and a new anthropology, but a most aggressive idealistic reaction against science and reason.

References 1. Dewey J (1910) The influence of Darwin on philosophy, “Popular Science Monthly”, July 1909, reprinted in The influence of Darwin on philosophy and other essays in contemporary thought. Indiana university Press, Boomington, p 9 2. Darwin CR (1958) The autobiography. In: Barlow N (ed). Collins, London, p 55 3. Manier E (1978) The young Darwin and his cultural circle. Reidel, Dodrecht/Boston 4. Darwin CR (1861) On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life, 3rd edn. John Murray, London, pp XII–XIX 5. Various essays are devoted to these authors in the symposium edited by Glass B, Temkin O, Straus WL, Forerunners of Darwin: 1745-1859. John Hopkins Press, Baltimore, 1959 6. Some of Lovejoy’s essays are reprinted in Forerunners of Darwin, cit.; see also his Bergson and romantic evolutionism: two lectures. University of California Press, Berkeley, 1914 7. Lovejoy A (1936) The great chain of being. A study in the history of ideas. Harvard University Press, Cambridge, MA 8. Cassirer E, The problem of knowledge. Philosophy, science and history since Hegel, chapter 2. The fourth volume of Das Erkenntnisproblem in der Philosophie und Wissenschaft neuren Zeit (1911-), written in German in Goteborg in 1940, was translated by Woglom WH and Hendel CW, and first published by Yale University Press, New Haven, 1950. See also: Regelmann JP (1979) Die Stellung der Biologie in den neukantischen Systemen von E. Cassirer and N. Hartmann. Acta Biotheoretica XXVIII:218–226; Ferrari M (1996) Ernst Cassirer. Dalla scuola di Marburgo alla filosofia della cultura. L.S. Olshki, Firenze, pp 105–106 9. Guyeńot E (1941) Les sciences de la vie aux XVIIe et XVIIIe sie`cles. Albin Michel, Paris 10. Harris M (1968) The rise of anthropological theory. Crowell, New York, p 290 ff, 299–302; Mayr E (1982) The growth of biological thought. Diversity, evolution and inheritance. Harvard University Press, Cambridge, MA, p 331; Freeman D (September 1974) The evolutionary theories of Charles Darwin and Herbert Spencer. Current Anthropol 51:3; Haines VA (1991) Spencer, Darwin and the question of reciprocal influence. J History Biol 24:3. A general discussion by various author is contained in a sourcebook: Herbert Spencer. critical assessment. In: Offer J (ed). Routledge, London/New York, 2000 11. Elliott P (2003) Erasmus Darwin, Herbert Spencer, and the origins on evolutionary worldview in British Scientific Culture, 1770-1785. Isis 94:1–29; see also Duncan D (1904) The life and letters of Herbert Spencer. Appleton, New York; Rumney J (1937) Herbert Spencer’s sociology. Williams & Norgate, London; Burrow JW (1966) Evolution and society: a study in Victorian social theory. Cambridge University Press, Cambridge; Peel JDY (1971) Herbert

68

P. Casini

Spencer. The evolution of a sociologist. Heinemann, London; La Vergata A (1995) Herbert Spencer: biology, sociology and cosmic evolution, in biology as society, society as biology: metaphors. In: Maasen S, Mendelssohn E, Weigart P (eds). Kluwer, Dordecht; Taylor MW (2007) The philosophy of Herbert Spencer. Continuum Books, London 12. Spencer H (1904) Autobiography, 2 vols. I. Williams and Norgate, London, p 176 13. Spencer H (April 1857) Progress: its law and cause. The Westminster Review, vol. 67, Apri1 1857, p 445–465 14. Spencer H. The development hypothesis (first published with no author’s name in the periodical "The Leader", 20 March 1852, p 280–281), was reprinted in Essays, Scientific, Political & Speculative, London, 1891, 3 vols, I, p 1-7. Autobiography, cit., and p 7;http://victorianweb. org/science/science_text/spencerdevelopment_hypothesis 15. Spencer H (1858) Essays: scientific, political and naturalistic. Williams & Norgate, London 16. Darwin to Spencer, 25 February 1858, The correspondence project, n. 2373: www. darwinproject.ac.uk 17. For instance, Autobiography, cit., II, p 27 18. Spencer to Darwin, 22 February 1860, ibid., n. 2706b; also Spencer’s Autobiography, cit., II, p 50 19. Darwin to Spencer, 23 February 1860, The correspondence project, cit., n. 2714 20. Darwin to Charles Lyell, 25 February 1860, ibid., n. 3126 21. Darwin to Hooker JD, 23 June 1863, ibid. n. 4212 22. Quoted in Spencer H, Autobiography, cit., II, pp 99–100 23. Spencer H (1852) The development hypothesis. Westminster Rev 57:490, cit. 24. Darwin to Hooker, 10 December 1866, The correspondence project, cit., n. 5300. 25. Darwin C (1869) On the origin of species. John Murray, London, pp 72–73 26. Taylor MW (2007) The philosophy of Herbert Spencer, cit., p. 74 27. The autobiography of Charles Darwin, 1809–1822, with original omissions restored and edited with appendix and Notes by his grand-daughter Nora Barlow, Collins, London 1958, pp 108–109 28. Darwin C (1860) On the origin of species, p 131 29. Darwin C (1868) The variation of animal and plants under domestication, vol II. Murray, London, pp 430–31 30. Darwin to Asa Gray, 22 may 1860, The correspondence project, cit., n. 2814; and Darwin, The variation of animal and plants under domestication, cited, p 432 31. Darwin C Autobiography, cit., p 91 32. Huxley TH (1898) Hume, with helps to the study of Berkeley. Appleton, London, pp 214–229 33. Huxley TH (1895) Evolution and ethics. Pilot Press, London 34. Richards RJ The Tragic Sense of Life. Ernst Haeckel and the Struggle over Evolutionary Thought. The University of Chicago Press, Chicago and London, 2008; S. Gliboff, H.G. Bronn, Ernst Haeckel and the Origins of German Darwinism. A Study in Translation and Transformation. The MIT Press, Cambridge Mass. and London, 2008 35. Strauss D der Bekenner und der Schriftsteller, 1873 (my translation from Unzeitgem€asse Betrachtungen I }7: www.nietszchesource.org.text/eKGWB DS). See: Stegmaier W Darwin, Darwinismus, Nietzsche. Zum Problem der Evolution, in “Nietzsche-Studien”, 16 (1987), p. 264–87; W. M€ uller-Lauter, L’organismo come lotta interna. L’influsso di Wihelm Roux su Friedrich Nietzsche, in G. Campioni – A. Venturelli (eds) La “biblioteca ideale” di Nietzsche, Guida, Napoli 1992; A. Venturelli, Genealogie und Evolution, in Kunst, Wissenschaft und Geschichte bei Nietzsche, De Gruyter, Berlin-New York, 2003, pp 238–253 36. Nietzsche F Daybreak (1881) } 49 (my translation from the German Morgenr€ote, www. nietszchesource.org.text/eKGWB M) 37. Nietzsche F Posthumous fragments (1869–1888) (www.nietszchesource.org.text/eKGWB NF-1888.14, 123 and 133). 38. Nietzsche F (2003) The Genealogy of Morals. English translation by H.B. Samuel, Boni and Liveright, New York 1913, reprint in Dover Publications, ibid., 2003, p 52; p 11 39. Nietzsche F (2002) In: Williams B (ed) The gay science. Cambridge University Press, Cambridge 40. Bergson H (1969) L’e´volution creátrice. Presses Universitaires de France, Paris 1969, p 248 ff

Struggle for Existence: Selection, Retention and Extinction of a Metaphor* Peter Weingart

Abstract Darwin’s famous phrase of the “struggle for existence” is taken as a metaphor. Semantically it has its origins in everyday language but was given a specific meaning in the context of his theory. Subsequently, the metaphor was transferred back into everyday use but also had an impact on the historical and social sciences. Darwin’s metaphor is one of the most famous cases of this type of metaphor transfer into the sciences and back. The analysis focuses on the German context where the phrase was translated into “Kampf um Dasein.” The “Kampf” metaphor’s role in various different contexts (discourses in the popular press) reveals the multifariousness of its usage. It reaches from the navy policy to colonialism and commerce and ultimately played a normative role in Nazi race hygiene policy.

Darwin’s famous phrase ‘struggle for existence’ is taken as a metaphor. Semantically it has its origins in everyday language but was given a specific meaning in the context of his theory. Subsequently, the metaphor was transferred back into everyday use but also had an impact on the historical and social sciences. Darwin’s metaphor is one of the most famous cases of this type of metaphor transfer into the sciences and back. Friedrich Engels wrote: “The entire Darwinian theory of the struggle for existence is simply the transfer of the Hobbesian theory of bellum omnium contra omnes and the bourgeois-economic one of competition as well as Malthus’s demographic theory from society into organic nature. After having accomplished

*This contribution is an excerpt from S. Maasen, P. Weingart, Metaphors and the Dynamics of Knowledge, Routledge 2000, chapter 3. The material for this study was collected in a research project carried out together with Kurt Bayertz and J€ urgen Kroll. P. Weingart (*) Institute for Science and Technology Studies (IWT), University of Bielefeld, Bielefeld, Germany e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_5, # Springer-Verlag Italia 2012

69

70

P. Weingart

this trick . . . it is easy to transfer these theories back from natural history into the history of society and to claim one had proved this thesis as an eternal natural law of society”. This famous interpretation of Darwin’s theory has been repeated by Nietzsche, Spengler, and countless other less prominent scholars to this day. It also underlies the general understanding of Social Darwinism and contains a description of the origin and function of metaphors in science. It provides an example of three different ways in which metaphors are used as media of exchange of meaning: (1) from everyday language to scientific language, (2) from the language of one scientific discipline to that of another; and (3) from scientific to everyday language. The history of science is full of examples of each of these cases, much has been written on them, and it can no longer come as a surprise that metaphors reflect the links between scientific, social, and political discourses. In the first case, concepts used in science have their semantic origins in everyday language, but are given a specific meaning linked to a theoretical (scientific) context. This is often the case prior to the invention of artificial terms designed to distance scientific from everyday language. In the (third) case of the transfer back from science into non-scientific contexts, or in Engels’ words, from ‘natural history’ into the ‘history of society’, the authority of science is carried by or attributed to the metaphor. It may be (and often is) taken as representing a proven theory, an ‘eternal natural law’, and not just as an illustrative analogy that could easily be replaced by another one. This recourse to the authority of science, be it implicit or explicit, by no means requires a precise or ‘justified’ (from the viewpoint of the respective discipline) application of the metaphor. In fact, the metaphor may be ‘misused’ and/or ‘abused’, that is, a different meaning in the new context or a normative meaning may be given to it. In these cases, ideologies, entire world views, ‘Weltanschauungen’, are elevated to the level of scientific truths. This can be seen as an aspect of the process of ‘scientification’. While the large majority of transfers involves single concepts with very limited connotations, some cases stand out where a few concepts represent a self-contained theory and develop into a coherent world view. The account to follow will show (thereby giving further empirical support to some studies) that Social Darwinism was less prevalent in those contexts where it was claimed by historians to be strongest. More importantly, it will give evidence to the phenomenon that the transfer of the metaphor back from science into public and political discourse entails an immense expansion and diversification of meanings. It will show further, how the meaning of the metaphor changes as its conceptual environment changes.

1 Kampf ums Dasein: Popularization and Contexts of Usage: Darwin’s Usage and German Translation In one form the metaphor already appears in the subtitle of the Origin of Species as the preservation of favoured races in the struggle for life. The third chapter of the book is entitled ‘Struggle for Existence’, and in it Darwin spells out the bearing of

Struggle for Existence: Selection, Retention and Extinction of a Metaphor

71

the struggle for life on the process of natural selection and species differentiation. Here he also remarks on the status of the term struggle for existence: namely, that he uses it ‘in a large and metaphorical sense, including dependence of one being on another, and including (which is more important) not only the life of the individual, but success in leaving progeny’ ([8], p. 116). It should suffice here to refer to some of those studies that have looked very carefully at the origins of the metaphor. Young traces it primarily to Malthus’ Essay on the Principle of Population and to Charles Lyell’s Principles of Geology stressing the ‘common context of biological and social theory’ ([37], pp. 109–45; [36], p. 43 et passim). Bowler has shown the discontinuities in detail in the use of the concept of struggle between Darwin and Malthus which centres around the difference between intraspecies competition and interspecies struggle ([7], pp. 63I–50). Leaving the interpretation of the finer grain to the historians of Darwin, one obvious conclusion is that a common term like ‘struggle’ was used widely by scientists, was taken from everyday language, and employed consciously as a metaphor. An important aspect is pointed out by Bowler. Regardless of the differences between them, Malthus and Darwin both took part in a period of intellectual change during which the view of nature and society as a harmonious system gave way to one characterized by the ‘law of struggle’ ([7], p. 644). Since the concern here is with the German career of Darwin’s metaphor, the first issue is its translation. Albeit a story all by itself, a few remarks are in place. In the first translation of the Origin by H. G. Born, ‘favoured races’ was translated to ‘vervollkommnete Rassen’ which actually means ‘perfected races’. That did part of the damage (notwithstanding the correction in the second translation by Victor Carus in 1867). Darwin’s interchangeable use of ‘struggle for life’ and ‘struggle for existence’ was translated to Kampf ums Dasein [2]. That implied even more damage since struggle for life could be translated more adequately into ‘Kampf ums Leben’ which would easily encompass both meanings Darwin had in mind, namely the struggle for survival of a species in a certain environment of other species under particular ecological conditions, as well as the individualistic struggle between members of the same species. ‘Kampf ums Leben’ or perhaps € even more adequately ‘Kampf ums Uberleben’ would suggest the unconscious, general struggle for survival in the natural environment while ‘Kampf ums Dasein’ assumed the connotation of an individual, conscious, and ultimately lethal conflict. In this connotation the metaphor is suggestive of the Hobbesian vision of the ‘bellum omnium contra omnes’ The damage was complete with the combination of ‘perfection’ and the struggle metaphor to ‘Vervollkommnung durch den Kampf ums Dasein’ (that is, perfection through the struggle for existence), because this elevated the metaphor to the level of the normative and instrumental as was later exemplified by the eugenicists’ strategy to ‘perfect the human race by eliminating the unfit’ [27]. When speaking about ‘damage’ we do not intend to leave our neutral position of observation. Rather, a dividing line between neutral science and value-laden

72

P. Weingart

political use of the Darwinian metaphor is implied. The very fact that the seemingly simple translation from one language into another could produce the change in meaning of which it is also known to have occurred in the transfer from one context (scientific) to another (political) within the same language demonstrates the elusive nature of metaphor: floating freely between contexts of use.

2 The Kampf Metaphor and the Reception of Darwinism in the Popular Press The popularization of the metaphor is illustrated by its career in Germany’s foremost encyclopedia. By 1872 it was already listed as a commonly used term in connection with Darwinism, but by 1898 it had achieved the elevated status as an independent entry in the famous Brockhaus Lexikon. Beyond this the picture becomes more complicated. Studies of the public impact of scientific theories suffer from the well-known difficulty that usually little is known apart from the circulation figures of books and journals and more or less well-informed guesses about their readers. From there it is still a long way to empirical evidence of their impact, that is, by shaping opinions and attitudes. With respect to Darwinism, numerous studies with diverging results have been undertaken [10, 19, 20]. It cannot be claimed here that the methodological difficulties have been overcome, but only that the evidence has been substantiated. We will first look at a selection of popular science journals, the assumption being that they had their readership primarily among the ‘Bildungsb€urgertum’ and, thus, among the opinion-leading elite of the German empire during the last quarter of the nineteenth century. Then, that analysis will be supplemented by a look at a number of political arenas with which Darwinism in its analogical use has most often been associated. Here, periodicals, newspapers, and newsletters of pertinent associations are the basis of the analysis. Finally, we look at publications submitted to the famous Krupp Prize Competition. While this procedure cannot claim to be a systematically drawn sample it does cover a broad range of publications supporting the assumption that we should get a fairly representative picture of the different discourses in which the ‘Kampf’ metaphor played a role. One of the first popular science journals to take up Darwin’s ideas in Germany was the weekly Ausland (Abroad). Although sceptical at first, by 1865 it had become a fervent supporter of the ‘new biological theory’. Its self-posed question – what makes Darwin so popular? – the journal answered by stating that although the theory was not proved, and with respect to its claims about the past probably never could be proved, it represented a ‘unified principle or ‘Weltanschauung’. Because of the theory’s analogical character for many neighbouring fields (see [1]), it had brought about a new age. At the beginning of the 1870s, the journal’s editor, Friedrich von Hellwald, like many other authors at the time of the Franco-Prussian War, resorted to Darwinism as proof that war was a natural law. The theory of the struggle for


73

existence that applied to societies must also be applicable to the relationship between peoples. The war between the civilized people (Kulturv€olker) of Europe against the ‘primitive’ people (Naturv€ olker) had to be understood as‚ Kampf ums Dasein’. During the decade of 1870–1880, Ausland became the chief popularizing journal for Darwin’s theory but, as Zmarzlik points out, its glorification of the ‘Kampf ums Dasein’ ran counter to the ethical values held by the bourgeois public. Therefore, in the 1880s, it radically changed its editorial policy [38]. Von Hellwald, who had been the chief propagator of Darwinism in the journal, gave up his editorship in 1884, complaining to his friend Ernst Haeckel that his efforts had not been very successful now that the times had turned away from the theory of evolution. Seven years prior to that he had welcomed the appearance of another new journal that had taken over the lead in representing the Monist ‘Weltanschauung’: Kosmos. Kosmos was a Monist journal ‘based on the theory of evolution in connection with Charles Darwin and Ernst Haeckel which first appeared in 1877. As an explicitly Darwinian journal, it self-confidently anticipated resistance from the public and, thus, a ‘Kampf ums Dasein’ (Kosmos 1877, pp. 1–3). Although at first embracing the humanities as well as the sciences, the journal shifted its focus to evolution after 5 years. Most prevalent were discussions on theories of heredity (notably Weismann’s) and selection. In the latter context a wide range of applications of the Kampf metaphor can be found. From the interpretation of human history to the theory of all living organisms, from the history of science and competition between ideas to the struggle between cells, the concept was used as a modelling device. One theme which attracted special attention in the journal was also the prominent example of the Social Darwinist debate. This concerned the question whether Darwin’s theory was socialist or aristocratic, an issue that arose out of the famous dispute between Virchow and Haeckel in which Virchow had attacked Darwinism as a theory that could be adopted by Social Democrats and was, thus, dangerous. Haeckel had responded by pointing out that Darwinism was ‘aristocratic’ rather than democratic and even less socialist because of its principle of the survival of the fittest which had been translated into ‘victory of the best’. During the first 5 years of its existence, Kosmos was a Social Darwinist journal propagating the aristocratic orientation of Darwin’s theory of selection. In transporting political messages with Darwin’s theory it was an exception at the time, but did introduce a new dimension that was to gain ground later on. In the early 1880s the increasing number of critical voices indicated that the enthusiasm for the Darwinist fad had subsided. The Kampf metaphor came into disrepute as a ‘vague and ambiguous term with which so many Darwinists in lack of a definite category were befogging themselves’ ([34], p. 355). What to some appeared as loss of meaning, to others was evidence of success. After 10 years of publication, the editor of Kosmos announced its demise, turning defeat into victory claiming that the theory of evolution had not only gained unquestioned authority in biology but had also become a self-evident and irrevocable prerequisite in other

74

P. Weingart

disciplines (Vetter 1886, p. 92). Contrary to this evaluation, the journal had obviously lost the ‘Kampf ums Dasein’ which it had anticipated at its birth. In other periodicals Darwinism played a much smaller role, but its diffusion and popularization followed very similar patterns. One of the most widely read journals at the time, the Deutsche Rundschau, until the turn of the century carried relatively few articles on Darwin’s theory and almost none with a Social Darwinist flavour, with the notable exception of Oscar Schmidt’s Darwinismus und Socialdemokratie [25]. More prevalent were philosophical essays on the implications and limitations of the theory of evolution for ethics, the history of ideas, etc. Another widely circulated review for politics, literature, and art, Die Grenzboten (Frontier Messengers), which until the formation of the empire had been the most influential organ of the liberal bourgeoisie, had by 1871 allied itself with the National Liberal and anti-Catholic camp of Bismarck allies. At the same time it was decidedly anti-Darwinian, and by 1900 the journal declared that the twentieth century did not want to have anything to do with Darwinism. The axiom of the ‘Kampf ums Dasein’ was attacked as the ‘same sophistry which had led to imperialism and anarchy’ ([12], p. 51). By the early 1890s, authors even commented on the loss of attention to Darwinism. It had become common knowledge rather than being limited to science, and in this process it had lost its attraction. Even the theologians had recovered from their shock. At the same time science, that is, biology, had calmed down, the revolution had gone into its second generation, specialization set in and for the lay public it became ever more boring [5]. Throughout this time the debate over the aristocratic versus the democratic or socialist character of Darwin’s theory continued, demonstrating not only the suitability of the theory as a ‘Weltanschauung’, but also its ambiguity with respect to conflicting political positions. The ultimate issue was whether society was based on a selective struggle for existence with the survival of the ‘best’ or whether that struggle led to their degeneration and eventual demise. ‘Struggle’ as the agent was undisputed. The relationship of Marxist and Social Democratic authors to Darwinism must be seen in the context of social, political, and economic events occurring in the last quarter of the century. In 1873 the great depression set in and initiated a change in the political climate, notably a discrediting of political Liberalism and enthusiastic Manchester capitalism. The dramatic structural changes, industrialization, and urbanization, brought the working class into politics and created widespread fear of the socialist movement among the middle class and the aristocracy. While the defence and legitimation of power interests on the part of the ruling classes is usually taken as the basis of Social Darwinism, the reception of Darwinism by the political Left is overlooked. During the election campaign for the Reichstag in 1877, August Bebel attacked Prussian militarism in a brochure, pointing out that war and the military system had degenerating effects on the population. In support of his thesis, he cited a passage from Haeckel’s Nat€ urliche Sch€ opfungsgeschichte which Haeckel himself omitted from later editions of the book. This episode is typical for the ambiguity of the Kampf metaphor with respect to its evolutionary or degenerating effects, which


75

recurs in the shift of arguments from eugenicists before and after World War I. Typically, Marxists and Socialists denied the interpretation – referring to Darwin – that the ‘struggle for existence’ had to be an inevitable conflict between individuals; they focused on the negative results of individual competition and pointed to the superiority of mutual help. Since the difference between the individualistic stance of Darwinism and the collectivistic philosophy of Socialism seemed to represent a contradiction between them, a flood of publications was devoted to the defence of the commensurability of Socialism and Darwinism [3, 16, 18, 26]. Socialist authors used Darwin’s theory as proof for the materialist alternative to religious explanations of man’s creation and the role of such explanations in legitimating the existing social order, notably the monarchy. The scientific authority of evolutionary theory was seen to coincide with the claims to the scientific nature of Marx’s theory of social evolution. Evolution in nature counted as scientific proof that social progress had to take place with the same law-like necessity. This association of Socialism with Darwin’s scientific theory was carried on through the 1890s and explains the impact on and fascination of Socialist authors like Kautsky and Bebel with eugenic schemes, in spite of the fact that they were much more explicitly selectionist and Social Darwinist than the various applications of the Kampf metaphor. The same association had already motivated Virchow in 1877 to criticize Haeckel and the attempts of his followers to include Darwin’s theory in school curricula. In his famous talk before the 50th convention of the Gesellschaft der Naturforscher und A¨rzte (then the foremost German scholarly association) he insinuated in calculated vague terms a relation between Darwinism, Socialism, and the Paris Commune, most likely because he feared that if the same were done by reactionaries, the relative freedom gained by science after the unification of the empire could be jeopardized [33]. It did not help Haeckel to insist that if any political tendency were to be attributed to Darwin’s theory, it could only be an ‘aristocratic’ and hardly a socialist one. In summary, scanning the range of major periodicals attached to various political positions, two points stand out. The reception of Darwinism, notably of struggle for existence, follows the pattern of fashion, that is, it declines as it becomes more widely diffused; and its use as an ideology is not limited to one group whose interests it supposedly matches, but rather by many groups who interpret it as they choose. This usage, both ubiquitous and heterogeneous, renders it problematic, if not outright false, to assume a specific impact of the theory be it instrumental or legitimating. However, while the usages are always specific and, hence, diverse, they are united by the fact that they all take recourse to the authority of science and natural laws in order to give credibility to their specific brand of ideas, opinions, and arguments. The pressure toward scientification thus enforces the usages of (that is, Darwinian) terms and concepts, which, in the course of this happening, assume their (at times bewildering) connectivity to a multitude of discursive arenas.

76

P. Weingart

3 Darwinism in Political Arenas 3.1

War and the Military

It comes as no surprise that, given its origin in everyday language, the Kampf metaphor assumed different meanings in different contexts and at different times. The most conspicuous example for the ambiguous use of the metaphor came to dominate public and scientific discussions about the impact of Darwinism: the association of the metaphor with war between peoples and nations. The connection may have contributed to the idea that war means progress although even that idea was not new. A look at the popular scientific literature in which the metaphor appears shows, that from the late 1860s onward, the metaphor is used extensively and with increasing radicalism to justify war as a natural principle. After the turn of the century a radical author like Klaus Wagner writes in Darwinian terms of the ‘selective struggle for new space’ (Auslesekampf um Neuland), the ‘great cultural significance of the selective struggle for existence’ (hohe Kulturbedeutung des auslesenden Daseinskampfes), the ‘selection of peoples as natural selection’ (V€ olkerauslese als nat€ urliche Auslese), and propagates explicitly the enslavement of the ‘lower peoples’ in what was or was to become the colonies [35]. The identification of the Kampf metaphor with the German war ideology became a major topic of English and French popular writings during World War I and served to associate Social Darwinism and German militarism. This helped to put the blame for both on the specific German use of the term and to overlook two important aspects: ‘War Darwinism’ as La Vergata calls it, had adherents elsewhere, and it added little or nothing to the militarist defence of war other than a new metaphorical repertoire and its scientific prestige, as well as giving evidence of the almoszt unlimited variety of interpretations of Darwin’s theory [21]. The usurpation of the Kampf metaphor by saber-rattling militarists makes it seem as if there were no other voices. However, the Social Democrats gave a different reading of Darwin. For Alfred Dodel-Port, Darwin had not taught that the evolution of the human race was to be sought in bloody fight between peoples, but in the care and strengthening of intellectual powers and social instincts [9]. And Karl Kautsky attacked “vulgar jurists, economists and historians who did not have any clue about the sciences as well as scientists and medical doctors who did not know anything about the social conditions and developments for giving any struggle in history the same name, no matter how it originated: to them they were all ‘K€ampfe um’s Dasein’” [17]. Analysts within the peace movement deplored the popularity that the metaphor and the theory about the struggle for existence had assumed because of the Franco-German war and attacked the mindless analogy between nature and human society. The same critical stance can be identified after the First World War when M€ uller-Lyer branded Social Darwinism as a ‘cultural zoology’ that had become an ‘intellectual plague’ after the war of 1870–1871 ([22], p. 95). The meaning of ‘struggle’ had become so broad that it no longer differed from other concepts such as ‘competition’.


77

Thus, one reads about peaceful Eskimos fighting the struggle for existence in the Arctic, and the millions of Chinese doing the same while living from their gardening, ‘even though it could only be a struggle with their vegetables’ [11]. These examples shall suffice to illustrate the association of the Kampf metaphor with war and, more specifically, the ways in which it was applied. There, the popularity of the metaphor is best explained by its versatility, instigating incessant debate. A related arena may be examined in which the language of ‘struggle’ and Social Darwinism has played a role: the build-up of the German Navy.

3.2

The So-Called Flottenfrage

The build-up of the German Navy became a prominent political issue in the last decade and a half before the turn of the century. At the time of rising nationalism and intensifying competition with the leading imperialist power Great Britain, support of the navy assumed an integrative function for the bourgeoisie, which was directed against the rising influence of Social Democracy. The Imperial Naval Office (Reichsmarineamt RMA) set up a special news bureau commissioned to mobilize mass support with popular and scientific propaganda. At the same time a number of organizations took part in these efforts, among them the All German Association (Alldeutscher Verband), the German Naval Association (Deutscher Flottenverein), and the Free Association for Naval Treaties (Freie Vereinigung fiir Flottenvertr€ age). In all of these, academics, professors, teachers, artists, and writers played a leading role, and the obvious focus of the RMAs propaganda was the ‘Bildungsb€urgertum’. The speeches, articles, and communications give a fairly accurate picture of the position of German scholars on the topic, and if Social Darwinist thinking was present it might be expected to be seen there. However, a review of the RMAs annual publication Nauticus, of the collection of speeches and opinion statements from German university teachers on the significance of the Flottenfrage, and of a survey conducted by the M€ unchner Allgemeine Zeitung, comes to a disappointing result. The Kampf metaphor had been generalized and segregated from its Darwinian context. The competitive struggle (Konkurrenzkampf) between classes, nations, peoples, shipping lines, for food and world markets, was the dominating terminology. An exception was Max Sering arguing explicitly against the theory of the Kampf ums Dasein, which he branded as non-scientific and only a pragmatic political argument used by the British Prime Minister. Repeatedly, and in spite of an abundance of Kampf and Dasein, in this discourse one can find explicit rejection of Darwin’s theory as British and not in line with German interests. Among the 50 odd scholars answering to the survey of the M€ unchner Allgemeine Zeitung in 1897 were such renowned names as Karl Binding, Felix Dahn, Hans Delbr€ uck, Max Weber, and the Darwinians Ernst Haeckel and

78

P. Weingart

August Weismann. Haeckel was the only one to speak of a ‘German Kampf ums Dasein next to other major powers in Europe’ ([2], p. 3). Thus, Steinberg may be right in a very general sense in saying: ‘The permeation of German academic thought by Social Darwinian conceptions led to widely-held views about the nature of politics as a struggle for survival. The state was a living organism engaged in a life and death battle’ ([29], p. 108). But here, when analysing the rhetoric of struggle, it is advisable to heed Kelly’s point to distinguish between “those who occasionally appropriated a Darwinian phrase or two and those who undertook a sustained and detailed application of Darwinism to human society. The first group – those vast ranks of saber-rattlers, socialist-baiters, and self-righteous rich who happened to live in a Darwin conscious age – can be called Social Darwinian only in the loosest sense of the word” ([19], p. 102). It is precisely the ‘loose’ usage, however which makes the Kampf metaphor such a general currency and keeps it alive.

3.3

Colonialism, Commerce, and Trade

In another related policy arena, that is, colonialism, commerce and trade, Social Darwinism is expected to be strongest if one is to rely on its almost proverbial association with capitalism. Surprisingly, especially in the area of trade, the almost complete absence of any allusions to Darwinism alongside the self-confident assertion of the right of the entrepreneur and the denial of equality to the workers is conspicuous. The only notable exception is Alexander Tille, who called himself in Haeckelian fashion a ‘social aristocrat’ and sought to turn Darwinism into a social ethic along the lines of early eugenic arguments. In his treatise Struggle for the Planet, he also followed the common racist topos that the ‘lower races’ were less efficient and would thus be pushed off the face of the earth [31]. Tille, when asked by Haeckel to collaborate in the Krupp Prize turned down the offer saying that to apply evolutionary theory to social theory the most elementary building blocks had not yet been assembled ([28], p. 10). The discourse on colonialism was primarily concerned with the imagined dangers of interracial marriages, and well into the first decade of the new century a biological concept of race in the strict sense can hardly be detected in colonialist writings. Purity of race was a distant derivative of the topos of the ‘struggle between nations’ insofar as it was considered an important prerequisite for success in that struggle, but ‘race’ was mostly used in a humanist connotation prevalent in anthropology at that time. Friedrich Ratzel, the founder of bio- or anthropogeography, who was later claimed by the Nazis as one of their own, in his more than thirty monographs and some 1,240 articles was far more sophisticated on issues such as the origin of the Aryan race and the demarcation between and the unity of races than was palatable for them. Thus, he had to be heavily censored in order to serve ideological purposes (see [13]). Ratzel started out as a Darwinian influenced by Haeckel, but by 1875


79

had turned against Darwin’s selectionism, characterizing it as the ‘crude hypothesis of the survival of the fittest in the struggle for existence’ [30]. Ratzel is often identified as a Social Darwinist because of his coining of the term Lebensraum which became the catch metaphor of colonialist and later ‘Greater German’ expansionism. Actually, he reinterpreted the Darwinian Kampf metaphor in Malthusian fashion. To a large extent Darwin’s often misunderstood and abused ‘struggle for existence’, in his opinion, had to be a struggle between living organisms for space ([24], p. 51). Thus, wherever one looks before 1890 – and the list could be easily extended – various public discourses, which are usually associated with Social Darwinism, actually show very little, if any impact of it. They do reveal a very loose usage of Darwinian thought and terminology, that is, of Darwinian metaphors, the most widespread of which is the Kampf metaphor. Kelly’s conclusion is corroborated: “Social Darwinism, in whatever form, never achieved a mass popularity.” And the few popular writers who talked a lot about struggle and race had such tenuous and ambiguous relationships to Darwinism that “it would be absurd to call them Social Darwinists” ([19], p. 109). This is not to be confused with the fact that the Kampf ums Dasein metaphor had become a highly inflated currency, together with elements of evolutionism and selectionism, that was being traded in all kinds of contexts with absolutely no relation to Darwin’s theory. Popular Darwinism, in contrast to Social Darwinism, had reached millions of readers by World War I not least through the writings of Wilhelm B€olsche, whose reading of Darwin was that nature not only showed brutal struggles for survival but also cooperation and love, especially on the higher levels of evolution [6]. I will skip the story of the Krupp Prize competition of 1900 which asked “what can we learn from the principles of the theory of descent with respect to the internal development and legislation of states?” except to say that the majority of entries leaned toward a very differentiated and careful adaptation of Darwin’s theory to society. Some advocated versions of state Socialism, mechanisms to protect the weak, and institutions of social welfare. Schallmayer’s eugenics was explicitly antiracist and, compared to authors like Tille and Woltmann, was moderately Social Darwinian. Kelly is correct in his judgement that most of the authors, despite their biologistic thinking, remained “committed to humanitarian values. This is an important point to keep in mind when drawing parallels between Social Darwinism and Nazism” ([19], p. 108).

3.4

The Normative Turn of the Kampf Metaphor

True as that may be when reading the essays of the Krupp competition, Kelly underestimates the fact that, after 1900, Social Darwinism appeared in a different disguise. The relatively vague Kampf metaphor had been translated into a fairly precise normative scheme of selectionist demographic and eugenic policy.

80

P. Weingart

To Alfred Ploetz, eugenics, or ‘racehygiene’ as he called it, was essentially a program to determine an optional organization of the ‘internal’ Kampf ums Dasein, that is, the struggle for reproduction and living conditions between individuals of one race, and of the ‘external’ struggle, that is, between races ([23], p. 22). In the racehygienic discourse, coupled with Weismannism and shortly after the turn of the century with a crude Mendelism, the notion of the ‘fit’ and the ‘unfit’ in the Kampf ums Dasein was translated by 1913 into a normative economic calculation of the ‘costs of the inferior to the state’ [15] and by 1920 into the supposedly humane suggestion to ‘destroy’ life not worth living (see [4]). In the context of Nazi ideology, ‘inferior’ assumed two meanings, both of which were apparent in the eugenic/racehygienic movement from its outset. To the anthropologically oriented wing of the movement (then to be called ‘racebiology’), ‘inferior’ pertained to the non-Aryan races including Jews; to the medically and social hygiene-oriented wing, its meaning combined supposed hereditary diseases like alcoholism and forms of behaviour judged to be antisocial’. Although neither Social Darwinism in the narrow sense of the word as it was represented by the authors of the Krupp competition nor popular Darwinism like Haeckel’s or B€olsche’s were officially accepted by Nazi propaganda, this does not warrant the conclusion that Darwin’s ideas had lost their effect or were ostracized. The National Socialist ‘Weltanschauung’ was shaped from a garbled mixture of biological holism equating notions of organism, race, and Volk, of evolutionism and hereditary theory. This mixture was declared to be the truly German Biology’ and was peddled by the biological profession as the core of public education. At the same time, the Nazis themselves made repeatedly clear that National Socialism was a political and not a scientific movement, and that it drew a sharp distinction between what science had determined as ‘reality’ and the various research areas and theories of individual scientists. Thus, neither Lamarck, Darwin, or Haeckel, regardless of their importance for the progress of science, nor any of their followers or opponents, could be equated with the movement. The leadership strategy of calling on the authority of science without becoming involved in ongoing debates and academic quarrels, and thereby retaining the charismatic authority of the leader, had consistently been employed by Hitler himself. In his notorious book Mein Kampf, a whole chapter was devoted to Volk and Rasse. Hitler never cited any of the sources he used, but it is obvious that he must have read much of the literature on racehygiene and race biology at the time (that is, 1924), as Fritz Lenz later proudly claimed. The chapter opens with an account of Darwin’s principle of the struggle of existence and selection, without a mention of Darwin, without even using the Kampf metaphor in full, and analogizing the struggle between species and the struggle between races. Kampf, he concluded, is always a means to promote the health and vigor of the species and thus the cause for its advancement. What follows is the murky language of racehygiene and race biology in which the state is to take an active role in the selection of the ‘fit’ and the preservation of racial purity ([14], pp. 313, 475–80).


81

4 Conclusions The most striking observation about the metaphor is the multifariousness of its usage. But, nonetheless, the metaphor has had its time. A search for ‘struggle for existence’ occurring in titles and/or abstracts of documents in both the SSCI and SCI databases revealed only 21 entries for the period 1973–1999 (SSCI: 15; SCI: 6 entries). Evidently it is justified to say that the struggle for existence as a metaphor has not survived the struggle for use and attention.

References 1. Ausland (1871) Was macht Darwin popula¨r? Ausland 44:813–815 2. Außerordentliche Beitr€age zur Allgemeinen Zeitung (1898) Nr. 1/1–1, Nr. 23/3–6 3. Aveling E (1897) Charles Darwin und Karl Marx. Neue Zeit 15:745–757 4. Binding H, Hoche A (1920) Die freigabe der vernichtung lebensunwerten lebens. Meiner, Leipzig 5. B€olsche W (1892) Wankt unsere moderne naturwissenschaftliche Weltanschauung? Neue Rundschau 3:62–72 6. B€olsche W (1913) Wankt unsere moderne naturwissenschaftliche Weltanschauung? Neue Rundschau 3:62–72 7. Bowler PJ (1976) Malthus, Darwin, and the concept of struggle. J History Ideas 3:631–650 8. Darwin C (1859/1968) The origin of species. Harmondsworth, Penguin 9. Dodel-Port A (1883) Charles Robert Darwin. Sein Leben, seine Werke und sein Erfolg. Neue Zeit 1:105–119 10. Ellegard A (1958) Darwin and the general reader. The reception of Darwin’s theory of evolution in the British periodical press, 1859–1872. G€oteborg: Acta Universitatis Gothoburgensis, G€ oteborg’s Universitets Arsskrift LXIV:241–393 11. Fried AH (1911) Handbuch der Friedensbewegung, Teil 1.: Grundlagen, Inhalt und Ziele der Friedensbewegung. Verlag der Friedens-Warte, Berlin 12. ‘Ethik und Politik’, Die Grenzboten (1900) 59:249–257 13. Haushofer K (ed) (1941) Friedrich Ratzel, Erdenmacht und V€olkerschicksal. Eine Auswahl aus seinen Werken. Kr€ oner, Stuttgart 14. Hitler A (1933) Mein Kampf. Verlag Franz Eher Nachf, M€unchen 15. Kaup I (1913) Was kosten die minderwertigen Elemente dem Staat und der Gesellschaft? Archiv f€ur Rassen- und Gesellschaftsbiologie 10:723–748 16. Kautsky K (1879) Darwinismus und Sozialismus. Der Sozialist 34 17. Kautsky K (1888) Kamerun. Neue Zeit 6:13–27 18. Kautsky K (1895) Darwinismus und Marxismus. Neue Zeit 13:709–716 19. Kelly A (1981) The descent of Darwin, the popularization of darwinism in Germany, 1860–1914. The University of North Carolina Press, Chapel Hill 20. Kohn D (ed) (1985) The Darwinian heritage. Princeton University Press, Princeton 21. La Vergata A (n.d.) Biology and war, 1870–1918 (unpublished manuscript) 22. M€uller-Lyer F (1919) Der Sinn des Lebens und die Wissenschaft, Grundlinien einer Volksphilosophie. Langen, M€ unchen 23. Pl€otz A (1895) Die T€ uchtigkeit unserer Rasse und der Schutz der Schwachen. S. Fischer, Berlin 24. Ratzel F (1901) Der Lebensraum. Laupp, T€ ubingen 25. Schmidt O (1879) Darwinismus und Socialdemokratie. Deutsche Rundschau 17:278–298

82

P. Weingart

26. Schmidt H (1890) Darwinismus contra Sozialismus. Neue Zeit 8:326–333 27. Schmidt H (1929) Der Kampf ums Dasein. Jena: Urania Verlagsgesellschaft 28. Schungel W (1980) Alexander Tille (1866–1912): Leben und Ideen eines Sozialdarwinisten. Matthiesen, Husum 29. Steinberg J (1964) The Kaiser’s navy and German society. Past Present 28:102–110 30. Steinmetzler J (1956) Die Anthropogeographie Friedrich Ratzels und ihre ideengeschichtlichen Wurzeln. Bonner Geographische Abhandlungen 19:86–88 31. Tille A (1897) Der Kampf um den Erdball. Nord und S€ud 80:68–96 32. Vetter B (1886) Abschiedsworte des Herausgebers. Kosmos 19:22 33. Virchow R (1922) Die Freiheit der Wissenschaft im modernen Staatsleben. In: Sudhoff K (ed) Rudolf Virchow und die deutschen Naiurforscherversammlungen. Akademische Verlagsanstalt, Leipzig 34. Wagner M (1884) Darwinistische Streitfragen, Teil III. Kosmos 14:55–362 35. Wagner K (1906) Krieg. Costenoble, Jena 36. Young RM (1985) Darwin’s metaphor, nature’s place in Victorian culture. Cambridge University Press, Cambridge 37. Young RM (1969) Malthus and the evolutionists: the common context of biological and social theory. Past Present 43:109–145 ¨ sterreichische Sozialdarwinisten. Ein Beitrag zur Brutalisierung des 38. Zmarzlik HG (1974) O politischen Denkens im sp€aten 19. Jahrhundert. Der Donauraum 19:147–163

The Theory of Evolution and Cultural Anthropology Henrika Kuklick

Abstract The relationship between cultural anthropology and Darwinism is complex. Contrary to what was once received wisdom, cultural anthropology was not inspired by Darwin’s ideas. Many nineteenth-century anthropological arguments predated Darwinism by a century or more. Yet, Darwinians figured prominently in organized anthropology in late-nineteenth century Britain, and when Darwin wrote The Descent of Man he drew upon the writings of an international population of anthropologists – although his most important sources were British. But cultural anthropology changed dramatically at the end of the nineteenth century, when its practitioners left their armchairs and took to the field – and conceptualized cultural variation in terms of Darwinian biogeography. Arguably, these practitioners, such as Baldwin Spencer, were influenced by the Darwin who wrote On the Origin of Species, not the Darwin who wrote The Descent of Man. And the disciplinary result of their labors was paradoxical: cultural anthropology informed by notions derived from Darwinian biology factored biological elements out of explanations of cultural variation.

I must begin with some definitions. To speak of “cultural anthropology” in the midnineteenth century, which is when my story necessarily begins, is to speak anachronistically. There was no such enterprise at that time. The family of inquiries that are collectively termed anthropology had three branches: one, prehistoric archaeology; two, anthropology – which meant investigations of humans’ physical characteristics; and three, ethnology – which then meant investigations of behaviors that humans learned (rather than performed instinctively) and which was a fundamentally historical pursuit. What was then often called ethnology was the member of the anthropological family closest to modern-day cultural anthropology, also known as social

H. Kuklick (*) Department of History and Sociology of Science, University of Pennsylvania, Philadelphia, PA, USA e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_6, # Springer-Verlag Italia 2012

83

84

H. Kuklick

anthropology (The names social anthropology and cultural anthropology have sometimes denoted different approaches, which have been linked to different national styles, but today socio-cultural anthropology is a relatively international enterprise). Because the bible provided an axiomatic background to early-nineteenth century ethnology, degeneration figured prominently in its narratives (as, of course, the biblical story of humankind was of descent from the perfection of Eden). In the second half of the nineteenth century, progress became the statutory story, and degeneration was understood as unnatural in the absence of some sort of conflict between peoples. In the early decades of the twentieth century, socio-cultural anthropology became sharply distinguished from ethnology; at that time, the objective of constructing historical backgrounds for their subjects’ then-current behavior became optional (if not irrelevant) for many practitioners. The rejection of historical analysis was an unanticipated consequence of research informed by evolutionary theory. We must also note that, with the possible exception of anthropologists in France, the division of labor among nineteenth-century anthropologists’ was hardly as clear-cut as it became in the twentieth century.1 Consider, for example, the British baronet and long-serving Liberal Party Member of Parliament John Lubbock (1834–1913), the child of a friend and neighbor of Charles Darwin – who served as an informal tutor to the young Lubbock. In 1871, Lubbock became the first president of the Anthropological Institute of Great Britain and Ireland (in and after 1907, the Royal Anthropological Institute), which incorporated all branches of anthropology. The scientific work for which Lubbock was best known was on insects, but his anthropological specialty was ethnology. Lubbock’s work was frequently favorably cited by Darwin in The Descent of Man, first published in 1871; indeed, although my generalization is based on impressions rather than calculations, I estimate that Darwin cited Lubbock more frequently than any other anthropologist in this book – and he cited an international congeries of anthropologists in it. Lubbock was also well known for his work in archaeology, and chose to become Lord Avebury when he was elevated to the peerage in 1900, naming himself after prehistoric megaliths he had studied and saved from destruction.2 Consider Lubbock’s contemporaries outside Britain. The best-known American anthropologist was the lawyer Lewis Henry Morgan (1818–1891) – probably most often remembered today for his influence on Karl Marx and Friedrich Engels – whose social theory Lubbock treated somewhat critically, as he did in his presidential address to the Anthropological Institute.3 Darwin was also critical of Morgan (although Morgan’s anthropology seems to have been of less interest to Darwin

1 See Emmanuelle Sibeud, “The Metamorphosis of Ethnology in France,” in Henrika Kuklick, ed., A New History of Anthropology (Oxford/Malden, MA: Blackwell, 2008), 96–110. 2 Henrika Kuklick, The Savage Within. The Social History of British Anthropology, 1885-1845 (New York: Cambridge University Press, 1991), 45–6. 3 John Lubbock, “On the Development of Relationships,” Journal of the Anthropological Institute 1 (1872): 1–29.

The Theory of Evolution and Cultural Anthropology

85

than what one might call – anachronistically – his ethology of the beaver). Given that Morgan had an identity as a naturalist, it is not surprising that his model of the course of human history had a biological component, rather than being strictly social: for example, he asserted that as humans’ brains grew in size as they negotiated the social developmental stages from savagery to civilization (a judgment with which Darwin agreed).4 And consider Germany’s pioneering physical anthropologist and ethnologist, respectively, the noted pathologist Rudolph Virchow (1821–1902) and Adolf Bastian (1826–1905) – who studied medicine with Virchow. Virchow, who was, like Lubbock, a liberal parliamentarian, promoted all types of anthropological inquiries; but, as Bastian also did, he insisted that these inquires were entirely discrete. Their example was followed by Johannes Ranke (1836–1916) who taught both cultural and physical anthropology when he was appointed in 1886 to the first university chair in anthropology in Germany, in Munich – the first professorship in the subject anywhere, to the best of my knowledge; but Ranke did not present his two subjects in tandem.5 In sum: although the intellectual projects of ethnology and physical anthropology may have been represented as distinct by nineteenth-century scientists, these projects coexisted within the persons of individual scientists, many of whom (inevitably) made intellectual connections between them. Note also that personal as well as intellectual ties joined many of the figures I am describing. How did Darwin describe his account of human history? In The Descent of Man he paid tribute to the eminent German biologist Ernst Haeckel, who was Virchow’s student and prote´ge´, but became his former mentor’s scientific opponent as a major proponent and popularizer of Darwin’s ideas in his country.6 Darwin said of Haeckel, “Almost all the conclusions at which I have arrived I find confirmed by this naturalist”; and Darwin claimed (however accurately) that he would not have completed The Descent of Man if he had not done so before Haeckel’s functionally

4

See, e.g., John Lubbock, “On the Customs of Marriage and Systems of Relationship Among the Australians,” Journal of the Anthropological Institute 14 (1885): 292–300; Lubbock’s attack is indirect here, on Morgan’s Australian disciples, Lorimer Fison and A. W. Howitt. For Darwin on Morgan, see Descent, 75, 84. On Morgan, see, e.g., Bernhard J. Stern, “Lewis Henry Morgan: American Ethnologist,” Social Forces 6 (1928): 344–357. 5 Andrew D. Evans, Anthropology at War. World War I and the Science of Race in Germany (Chicago: University of Chicago Press, 2010), 30. I do not consider comparable the appointment of Daniel Garrison Brinton as professor of ethnology and archaeology in the Academy of Natural Sciences in Philadelphia in 1884; technically, his appointment as professor of ethnology at the University of Pennsylvania in the same year as Ranke’s appointment, 1886, was the first in North America, but, as Regna Darnell observes, he received no salary and had no identifiable students; see her “North American Traditions in Anthropology,” in Kuklick, ed., 38. E. B. Tylor was promoted from a readership at Oxford to a personal professorship in 1896. 6 See, e.g., Robert J. Richards, The Tragic Sense of Life (Chicago: University of Chicago Press, 2008), 28.

86

H. Kuklick

equivalent work appeared.7 So Haeckel’s assessment of the development of anthropology as an enterprise is of some interest. In 1913, he delivered a lecture entitled “Fifty Years of Anthropology” to an International Medical Conference in London. In it, he identified three disciplinary foundational moments that occurred in 1863: a lecture he gave on Darwin’s theory of evolution at the Congress of Natural Historians at Stettin; the publication by the German Zoologist Karl Vogt of his Man, his Place in the Universe and in the History of Earth; and the publication by Thomas Huxley of his Man’s Place in Nature. All of Haeckel’s intellectual markers represented identification of the family relationships joining humans to other life forms as well as corroboration of his Biogenetic Law: “The human embryo repeats in its growth the history of the human race.” Darwin had certainly found clues to evolutionary relationships in embryonic forms, and Haeckel argued (somewhat self-servingly) that the study of comparative embryology was what distinguished the Darwinian understanding of human evolution; thus, in Haeckel’s account, there had been only a brief interval between the publication of On the Origin of Species and the emergence of the distinct scientific field of anthropology.8 Haeckel failed to mention – perhaps out of ignorance – that 1863 was also the year in which the Anthropological Society of London (ASL) was founded, seceding from and claiming a more uncompromisingly scientific approach than the Ethnological Society of London (ESL).9 The foundation of the Anthropological Society was inspired by that of the Socie´te´ d’Anthropologie de Paris, organized in 1859 by Paul Broca. In both groups, the predominant view was polygenism, the characterization of types of humankind as separate species, rather than varieties of a single species. Darwin explicitly rejected polygenism as inconsistent with the principle of evolution. The Darwinians among mid-century anthropologists largely remained in the ESL; indeed, the only Darwinian active in the ASL was Alfred Russel Wallace, usually remembered as the co-discoverer with Darwin of the process of natural selection – and he tried to reconcile the two anthropological factions.10 Did others agree with Haeckel’s judgment that On the Origin of Species inspired the development of anthropology? Certainly, there were others who agreed with his estimation of the scientific importance of the biogenetic law. For example, in 1890, the Oxford zoologist E. B. Poulton observed that “the great impetus given to biological inquiry by the teachings of Darwin ha[d] chiefly manifested itself in

7

Charles Darwin, The Descent of Man, Second Edition (New York: A. L. Burt, 1874), 3. Ernest Haeckel, “Fifty Years of Anthropology,” The North American Review Vol. 198, No. 696 (November 1913): 609–616; quote 610f. For Darwin’s embryology, see, e.g., Descent, 10. For Darwin’s rejection of polygenism, see, e.g., Descent, 200. 9 The definitive study of the split between the ESL and ASL – as well as their reunion in 1871 as the Anthropological Institute – is George W. Stocking, Jr., “What’s In a Name? What’s in a name? The origins of the Royal Anthropological Institute, 1837–1871.” Man n.s. 6 (1971): 369–90. 10 For Wallace’s efforts to reconcile the ASL and ESL viewpoints, see his “The Origin of Human Races and the Antiquity of Man Deduced from the Theory of ‘Natural Selection’,” Journal of the Anthropological Society of London 2 (1864): clviii-clxxxvii. 8


87

the domain of Comparative Anatomy, and especially in that of Embryology.”11 A reading of The Descent of Man might suggest that the formulation of the biogenetic law had been equally inspirational for anthropologists, since it was translated into generalizations about the course of human development by the many authorities cited by Darwin – who included not just Lubbock and Morgan but also such figures as Herbert Spencer, John McLennan, John Beddoe, and E. B. Tylor, the most prominent anthropologist in nineteenth-century Britain, the first to gain an academic position. In 1884, Tylor was appointed Reader at Oxford, and he is conventionally credited with formulating the definition of culture as learned behavior that remains foundational today.12 Darwin cast his net widely in searching for anthropological justification for the arguments he made in Descent. Indeed, the theoretical positions of Darwin’s anthropologist-sources ranged from the biblically-inspired notions of the early-nineteenth century British physician James Cowles Prichard (a pillar of the Ethnological Society of London) to the polygenism of the Americans Josiah Nott and George Gliddon. But Darwin seconded the judgments of prominent anthropologists of his day. If we focus on the persons whose theoretical views mattered to him, we are not surprised to see that they were overwhelmingly British, although British schemes bore considerable resemblance to those of the American Morgan and the German Gustav Klemm (whose voice in his country was a minority one).13 What was conventional wisdom among British anthropologists around the time that The Descent of Man was published? Humans in their primitive condition were engaged in a “Hobbesian war of each against all,” according to Thomas Huxley, who has been conventionally represented as “Darwin’s Bulldog” because he became Darwin’s public defender after the publication of On the Origin of Species in 1859 – and who played a major role in the anthropological community during the last third of the nineteenth century, not least as broker of the union of the ESL and the ASL as the Anthropological Institute. Nevertheless, “The savage is possessed of human reason and speech,” Tylor wrote, “indicating that his brain power . . . enables him to receive more or less of the education which transforms him into a civilized man.” This statement enunciated the principle of the “psychic unity” of all varieties of the human species, which implied that humans everywhere were capable of “independent invention” of the rudiments of civilization, if not its

11

Quoted in Richard Burkhardt, Jr., Patterns of Behavior (Chicago: University of Chicago Press, 2005), 2f. 12 Tylor’s first appointment at Oxford was in 1883 as Keeper of the university museum, and he became Reader in anthropology in the following year. 13 A major point of considerable contention between British anthropologists and Morgan was whether the original type of relationship between the sexes as what Morgan termed “primitive promiscuity” – which also seemed unlikely to Darwin; on this point see my “Humanity in the chrysalis stage: Indigenous Australians in the anthropological imagination, 1899–1926,” British Journal for the History of Science 39 (2006): 535–568. On Klemm, whose ideas were possibly an inspiration for Tylor, see Harry Francis Malgrave, “Gustav Klemm and Gottfried Semper: The Meeting of Ethnological and Architectural Theory,” Anthropology and Aesthetics 9 (1985): 68–79.

88

H. Kuklick

highest refinements. Everywhere, the course of peoples’ evolutionary advance through an ordered series of culture complexes was the same, although peoples’ negotiation of this course varied in pace and consistency; some developmental anomalies – so called “survivals” of past practices – invariably endured, even though they no longer contributed to the orderly operation of social life. As John Lubbock observed in 1870, progress was not inevitable: if a population had achieved perfect adaptation to its environment, it would not modify its way of life unless prompted to do so by some sort of novel stimuli. Nevertheless, when there was change, it had a virtually inevitable direction. To anthropologists, all of these evolutionary trends were consistent: from migratory lifestyles to settled ones; from practice of mating customs that violated Victorian standards of morality and represented defective understanding of biological kinship to the development of the monogamous and patriarchal family; from an undifferentiated political-social structure to a defined class system associated with an established government order that incorporated routinized patterns of succession to offices, which ruled by law rather than force; from simple to sophisticated technology; and so on. In general, evolutionary trends represented the triumph of rationality, science, and compassionate morality – all of these some functions of personal discipline. In Tylor’s summary formulation, the “wildman of the forest [was] forgetful of yesterday and careless of tomorrow . . . so wanting in foresight to resist passion and temptation.” Social evolutionists believed that contemporary primitives were much like the earliest humans, and all of these relationships were parallel: primitives to advanced peoples; the lower orders to the upper classes (mental defectives, the unredeemable poor known as the “residuum,” and the criminal classes were the most primitive of all); women to men; and children to adults. The development of the child recapitulated the development of the human species in both biological and social terms. Growing children in advanced societies recapitulated the moral stages of past ages while playing with toys that were the practical tools of their ancestors – the bow and arrow of the hunter and the rattle of the witchdoctor.14 Tylor often called anthropology the “reformer’s science,” the findings of which would enable the “great modern nations to understand themselves, to weigh in a just balance their own measures and defects” (prominent among these defects were “survivals” of the primitive past, which would presumably be eradicated once they had been identified and recognized for what they were). Thus, in the nineteenth century (unlike in the twentieth) the discipline’s purview was all types of human societies at all times. Nevertheless, anthropology’s most urgent task was recording what could be learnt about primitive peoples, whose culture (if not very physical existence) was destined to disappear with exposure to Western civilization. Compelling evidence was

14

The general discussion is in Kuklick, 1991, esp. 80–88. See 86 for the quotation from Huxley’s Social Diseases and Worse Remedies (1891), 80 and 86f for the quotations from E. B. Tylor, Anthropology (1881) and 82-3 for the discussion of John Lubbock’s The Origin of Civilization and the Primitive Condition of Man (1870).


89

provided by the extinction of the Tasmanians, who were imagined as the most primitive population who had survived until the modern era, the last full-blooded member of whom had died in 1876.15 Darwin’s account of human development was much the same. The human embryo’s developmental stages represented negotiation of the process by which the human species developed from lower forms. Useless biological features persisted in adults – survivals that preserved attributes of “our remote semihuman progenitors” – and were especially notable among mental defectives. Classifying human varieties as different species was unjustified, not least because interbreeding was evidently viable; there were not clear demarcations among types, since “they graduate[d] into each other.” Certainly, among contemporary primitives, relics of human biological development were more conspicuous than they were among advanced peoples. Primitives’ brains seemed smaller than those of advanced peoples (Australian Aborigines’ the smallest of all), and there was somewhat less physical variability among primitive than advanced populations. Moreover, different human types differed in mental qualities, “chiefly . . . in their emotional, but partly in their intellectual faculties.” Nevertheless, the differences among human types were relatively inconsequential, not least because considerable mental powers were required to survive in unimproved nature. And even the most savage of peoples, such as the Fuegians, displayed “many little traits of character showing how similar their minds were to ours”; the Fuegians’ behavior was but one expression of a general phenomenon evident from “Mr. Tylor’s and Sir J. Lubbock’s interesting works,” Darwin said. Independent invention followed from the consistency of humans’ mental endowments: ethnographic evidence proved that even the most primitive peoples were capable of making evolutionary progress. As primitives advanced, they developed aesthetic and moral sensibilities, notions of private property, fixed abodes, and formal government. Nevertheless, in the relatively near future “the civilized races of man [would] almost certainly exterminate and replace the savage races throughout the world.” Some climates were distinctly inhospitable, but the civilized would prevail everywhere that they could acclimatize (and civilized peoples’ capacities to adapt to varied climates were greater than primitives’ were). The limiting case of the Tasmanians (at the time of Darwin’s writing hovering on the brink of extinction) exemplified the process by which primitive peoples disappeared, being a product of both colonists’ deliberate efforts to eliminate them and their constitutional vulnerability.16 Most important, as we all know, when Darwin wrote about the human species, he was at his most Lamarckian – which is to say that he was at his least Darwinian, as we have come to understand this approach. In Darwin’s account, just as in the accounts of his

15

These characteristic remarks of Tylor happen to come from his introduction to Friedrich Ratzel, The History of Mankind (1896), quoted in Kuklick, Ibid, 7. For Tylor in 1893 on the Tasmanians, see Ibid, 251. 16 Descent, quotations, in order, 14, 199, 203, 191, 178; see also 10f, 17, 22, 32, 44, 60ff, 164, 105f, 151, 214, 209.

90

H. Kuklick

anthropologist-sources, habits became instincts and human history had an inherent direction. What does the historian of anthropology make of the relationship between Darwin’s ideas and those of his anthropologist contemporaries? Did On the Origin of Species inspire a congeries of thinkers to formulate arguments that Darwin naturally found congenial when he came to write The Descent of Man? Recall that this was Haeckel’s judgment, and it became received wisdom.17 But when the history of anthropology began to develop as a specialized scholarly subject several decades ago, it seemed especially important to establish that there had been no Darwinian impetus behind the emergence of the field itself. In such seminal works such John Burrow’s Evolution and Society, first published in 1966, much was made of the pre-Darwinian background to socio-cultural anthropological analysis. As Burrow insisted, it was essential to dispel the widespread belief that “the growth of social anthropology in the third quarter of the [nineteenth] century [w]as a kind of joyful and conscious imitation of the natural sciences.”18 Rather, the discipline had a number of antecedents in earlier thought of a strictly social character. In particular, conspicuous features of the model anthropologists shared with Darwin – the recapitulation hypothesis, the comparative method, the notion that human development proceeded through an ordered sequence of stages in which “survivals” from antecedent forms made progress somewhat disorderly – derived from the thinkers of the Scottish Enlightenment. Indeed, Enlightenment thinkers formulated the very definition of the minimal characteristics of civilization as settled habitation, private property, and stable formal government.19 Also central in Enlightenment thought was the notion of “sympathy,” the essential “social instinct” for Darwin, the existence of which was axiomatic for many late-nineteenth century social thinkers in Europe and America.20 It is evident that Burrow was right: the social theories that informed latenineteenth century anthropological thought had a considerable lineage, and did not derive from biological thought. It is also the case that Burrow was writing at a time when socio-cultural anthropologists considered their enterprise altogether distinct from biology, even when their colleagues included physical anthropologists, as has been traditional in anthropology departments in North America: anthropologists then wanted a past consistent with their present. Burrow did not trouble to consider the possibility that biological thought might have shaped cultural anthropology at the very end of the nineteenth century. But it was then, as I will argue in the remainder of this paper, that Darwinian ideas of the sort that we

17

For one effort to establish anthropology’s Darwinian pedigree, see A. C. Haddon, History of Anthropology (London: G. P. Putnam’s Sons, 1910). 18 J. W. Burrow, “Evolution and Anthropology in the 1860’s. The Anthropological Society of London, 1863–71,” Victorian Studies 7 (1963): 137–154, p. 141. 19 J. W. Burrow, Evolution and Society (Cambridge: Cambridge University Press, 1966), 10–16. 20 For one discussion, see Susan Lanzoni, “Sympathy in Mind (1876–1900),” Journal of the History of Ideas 70 (2009): 265–287.


91

now consider truly Darwinian – ideas typical of the author of the On the Origin of Species as opposed to the author of The Descent of Man – in fact become very important in analysis of social behavior. The – unanticipated – consequence of this development was the emergence of a cultural anthropology thoroughly differentiated from biological anthropology. Intellectual change had followed methodological change. That is, anthropologists’ perspective was altered as they turned away from what is conventionally termed “armchair anthropology” – the production of synthetic judgments on the basis of data that theorists did not collect themselves but culled from all manner of sources, a type of analysis widespread among diverse types of naturalists, of course. In the late-nineteenth and early-twentieth centuries, anthropologists from Britain, Germany, France, and North America took to the field to collect their own data. These fieldworkers had precursors – most notably the Berlin-based Adolf Bastian, whose career as a museum anthropologist included considerable fieldwork – but it was not until the end of the century that there was a substantial movement of academically-trained persons out of the shelter of their studies. In the received history of anthropology, the value of fieldwork was appreciated only as the result of a historical accident: in 1914, at the time that World War I broke out, Bronislaw Malinowski happened to be visiting Australia (to attend a meeting of the British Association for the Advancement of Science); as a citizen of the Austro-Hungarian Empire, he was identified as an enemy alien and trapped in the area for the duration of the war; he found himself with no option other than to pursue funding that allowed him to live in the field for an unprecedented period, and retrospectively recognized the merits of his protracted field research.21 But Malinowski himself acknowledged that he was inspired by a number of figures.22 Conspicuous among Malinowski’s anthropological forebears was Baldwin Spencer, foundation professor of biology at the University of Melbourne. And after reading Malinowski’s earliest ethnographic efforts, Spencer became an

21

For one reiteration of this story, see David M. Hoffman and Andrew M. Gardner, “Fieldwork and Writing From the Field,” in Gardner and Hoffman, Dispatches from the Field (Long Grove, IL: Waveland Press, 2006), 1 f. In fact, Malinowski had intended to spend two years in the field, and, thanks largely to the efforts of C. G. Seligman, his supervisor at the London School of Economics, had the wherewithal to do so; he was able to secure additional funds from the Australian government by promising to identify information useful to Australia’s colonial administrators. Michael W. Young, Malinowski. Odyssey of an Anthropologist, 1884-1920 (New Haven: Yale University Press, 2004). 245f, 437; see also Malinowski to Atlee Hunt, Secretary, Department of External Affairs, April 28, 1915, and Hunt to Malinowski, May 4, 1915, Yale University Archives, MS 19, Box 4. 22 Anthropologists’ fieldwork methods were in no small part borrowed from the methods of other practitioners of the sciences that derived from natural history, not least because a number of early field-going anthropologists were scientifically trained. For one account of the development of field method, which includes an analysis of the origins of Malinowski’s approach, see my “Personal Equations: Reflections on the History of Fieldwork, With Special Reference to Sociocultural Anthropology,” Isis 102 (2011): 1-33.

92

H. Kuklick

informal tutor to Malinowski for a time.23 Oxford-trained, Spencer was introduced to anthropology when he audited E. B. Tylor’s undergraduate lectures; and in 1885, together with his then-mentor, H. M. Moseley, Oxford’s Professor of Human and Comparative Anatomy, he assisted Tylor in setting up the exhibits in Oxford’s PittRivers Museum.24 Taking up his Melbourne post in 1887, Spencer did not enjoy his work, complaining in a letter to an Oxford classmate that his obligatory teaching of medical students was “the most monotonous and soul killing work imaginable.”25 It is not surprising that he found solace in anthropology, which increasingly occupied his intellectual attention after he served as the zoologist on the Horn Expedition to central Australia in 1894. While on the expedition, he met a long-serving civil servant who presided over Aboriginal affairs, F. J. Gillen (who acted as chief informant for the expedition’s anthropologist, E. C. Stirling), and the two established a durable research partnership.26 Spencer wrote all of the texts that were published under his and Gillen’s names and surely contributed much of their conceptualization, but he also invariably consulted Gillen. By 1913, Malinowski said of Spencer and Gillen that “half the total production in anthropological theory ha[d] been based upon their work, and nine-tenths affected or modified by it.”27 It is because their research on central Australia had an international impact that I will devote most of the remainder of my paper to it. In the Australian summer of 1896–1897, Spencer and Gillen did fieldwork for their first work, The Native Tribes of Central Australia, published in 1899. Focused on the Arrernte (whom they called the Arunta), it was what was then called an “intensive study,” a type of anthropological inquiry that had only just been defined (in opposition to survey research, such as that conducted by the 1898 Cambridge Anthropological Expedition to Torres Straits). The intensive study was justified with a plan for the development of a new sort of anthropology that was, in fact, never realized. That is, the intensive study would shortly become an end in itself, but it was initially rationalized as the fundamental building block of comparative

23

One testimonial to Spencer’s encouragement is Malinowski’s letter to his supervisor at the London School of Economics, C. G. Seligman, 4 May 1915, Malinowski Papers, file 27/3, London School of Economics. 24 D. J. Mulvaney and J. H. Calaby, ‘So Much that is New. Baldwin Spencer, 1860-1920 (Carlton, Victoria, Australia: 1985), 60. 25 Baldwin Spencer to W. E. Roth, 30 January 1903, S P, Box 1A. As the Protector of Aborigines for Queensland, Roth was himself able to devote considerable time to anthropological inquiry. Spencer also served as the editor of the Horn Expedition’s Reports. 26 Frank Gillen was Post and Telegraphs Stationmaster, stipendiary magistrate, and Sub-Protector of Aborigines for South Australia; his formal schooling ended when he was twelve. 27 Bronislaw Malinowski, Review of Across Australia by Baldwin Spencer and F. J. Gillen, FolkLore 24 (1913), 278.


93

analyses: as detailed studies of delimited areas accumulated, their results would be compared, and generalizations about human evolution would be formulated.28 As the world’s largest island, Australia was understood as a protected preserve for “living fossils,” ancient types of plants and animals that were extinct on the continents of the Northern Hemisphere.29 A general Darwinian principle explained the natural history of Australian life forms. That is, their vulnerability when confronted with imported forms – which had been demonstrated many times over as the plants and animals that colonists brought with them overwhelmed indigenous species – confirmed Darwin’s judgment that the geographical isolation necessary to species differentiation in the limiting case of island enclosure resulted in idiosyncratic types that were unlikely to survive competition with species bred in more competitive continental conditions.30 If cultural phenomena were analogous to biological ones, Australia’s human behavioral forms were also ancient, and the geographically isolated area of Central Australia was a preserve within a preserve, a virtual island where persons were relatively protected from the pressures of natural selection as these processes operated in the cultural realm. As the armchair anthropologist J. G. Frazer put it, in Central Australia “the scientific inquirer might reasonably expect to find [there] the savage in his very lowest depths, to detect humanity in the chrysalis stage.”31 In Spencer and Gillen’s words, the conditions of Central Australia had preserved creatures “that have everywhere passed away and given place to higher forms,” including “human beings that still remain on the culture level of men of the Stone Age,” persons who were exceptionally backward

28

A. C. Haddon to Baldwin Spencer, 5 May 1902, in the Spencer Papers, Pitt Rivers Museum, Oxford (subsequently, S P), Box 1. Near-contemporaries, Spencer and Haddon were both trained as biologists, and were professional rivals as such before they became like-minded anthropologists: Haddon was the runner-up in the competition for Spencer’s Melbourne chair. For Haddon’s endorsement of detailed study of a delimited area, as well as an account of the vicissitudes of his career, see Henrika Kuklick, “Islands in the Pacific: Darwinian Biogeography and British Anthropology,” American Ethnologist 23 (1996): 611–38. 29 As Patrick Brantlinger has documented, arguments that Australian Aborigines were inferior forms of humankind date to the beginning of British colonization of their land. Long before the promulgation of Darwin’s evolutionary theory, Europeans in Australia pronounced that Aborigines constituted “the connecting link between man and the monkey tribe,” as Peter Cunningham did in 1827; quoted in Brantlinger, Dark Vanishings (Ithaca: Cornell University Press, 2003), 117. On the general theme of Australia as a “zoological garden of living fossils,” see R. A. Stafford, “Annexing the landscapes of the past: British imperial geology in the nineteenth century,” in J. M. MacKenzie, ed., Imperialism and the Natural World (Manchester: Manchester University Press, 1990), 67–89, esp. 81–2. 30 For a general discussion of the putative plight of Aboriginal Australians, see Russell McGregor, Imagined Destinies. Aboriginal Australians and the Doomed Race Theory, 1880–1939 (Melbourne: University of Melbourne Press, 1997). For example, naturalists remarked upon the triumph of the English bee over the Australian bee, and plotted the rapid territorial expansion of introduced rabbits. For some naturalists’ observations, see Charles Nicolson to John Lubbock, 1857, Avebury Papers, British Library, Add.MS 49638; P. M. Byrne to Baldwin Spencer, 18 April 1895, S P, Box 1A. 31 J. G. Frazer, “The Origin of Totemism,” Fortnightly Review 71 (January-June 1899), 648.

94

H. Kuklick

because they had been “shut off from contact with other peoples,” deprived of the developmental “stimulus derived from external sources.”32 The Arrernte were so primitive that they were ignorant of the most basic facts of life – that pregnancy followed sexual intercourse and that deaths occurred naturally (rather than through the operation of witchcraft).33 Spencer and Gillen had no doubt that the way of life of the Arrernte would not long endure, even though the people had to a degree proved capable of turning the changes bought by European colonization to their own purposes; they incorporated rabbit fur in their personal adornments, for example, and adopted European tools.34 Spencer and Gillen were certain that “the once large and powerful Arunta tribe” would soon be reduced to a “degraded remnant.”35 Their judgment followed a conventional formula, derived from axioms of the evolutionist anthropology I have described: contact with Europeans so profoundly affected primitive peoples that they soon “lost the last remnants of their individuality”; and the larger was the cultural gap between the peoples in contact, the more rapidly would the less advanced society disintegrate.36 Nevertheless, Spencer and Gillen undertook to understand the Arrernte sympathetically. They became “fully-initiated” members of Arrernte society, who were able to learn secrets previously hidden from white men.37 They produced an account of Aborigines’ life in all of its aspects, ranging from everyday practices, such as making fire, and preparing Emus for eating; to aesthetic sensibilities, expressed in designs with which Aborigines decorated their bodies, their sacred objects, and the rocks and caves of Central Australia; to important ceremonies, such as circumcision rituals.38 Moreover, Spencer and Gillen urged anthropologists to put themselves “into the mental attitude of the native,” explaining that Aborigines’ lifeways were appropriate adaptive responses to the conditions of Central Australia, even when they violated European standards of propriety.39 They argued that

32

Balwin Spencer and F. J. Gillen, The Arunta (London: Macmillan, 1927), vii; Native Tribes, 54. See Native Tribes, 265, 356, 536–48. 34 Baldwin Spencer and F. J. Gillen, The Northern Tribes of Central Australia (London: Macmillan, 1904), 720; Native Tribes, 575. 35 Baldwin Spencer and F. J. Gillen, Across Australia (London: Macmillan, 1912), vol. 2, 300; and see Native Tribes, 7–8, 17–18. 36 This characteristic statement is from A. C. Haddon, “Manners and Customs of the Torres Straits Islanders,” Nature 42 (1890), 637–642, quote 638. See also Native Tribes, vii. For the translation of this generalization into a formula, see, e.g., W. H. R. Rivers, “Report on Anthropological Research Outside America,” in W. H. R. Rivers, A. E. Jenks, and S. G. Morley, The Present Constitution and Future Needs of the Science of Anthropology (Washington, DC: Carnegie Institution of Washington, 1913), 5–28. And see Native Tribes, vii. 37 E.g., Native Tribes, v. Spencer and Gillen’s claim was somewhat hyperbolic; they had been given local identities, but they did not have ‘fully-initiated’ status, not having experienced the rites de passage that would have conferred it. 38 Native Tribes, 584–6, 618–35, 218–51. 39 Native Tribes, 48; see also 25–6. 33


95

Aborigines had developed their “mental powers . . . along the lines which are of service to them in their daily life,” acquiring formidable memories and detailed knowledge of their natural environment. They pointed to “a gradual improved development which is still proceeding,” noting that Aborigines self-consciously undertook to implement sensible suggestions for progressive change made by the exceptionally talented persons among them.40 Indeed, they saw many admirable features in Aborigines’ way of life. Aborigines were, for example, devoted to their children, no less than the “average civilized parent,” as well as helpful and generous to white men – which, as Spencer and Gillen observed, they might well not have been, given the many wrongs that had been done to them.41 Even in the absence of formal government, they had developed a distinctive moral code that was rigorously enforced, which served to maintain social order, even though it differed from a “white man’s standard.”42 Most important, the Arrernte way of life was not to be understood as some function of biological endowments. This argument was predicated on Spencer and Gillen’s judgment that all of Australia’s Aborigines were a single people. They derived from a band of invaders who entered the country from some single port. But sub-groups of the invading population subsequently wandered all over Australia. Therefore, their cultural diversity – a prominent feature of which was their remarkable linguistic diversity – was strictly cultural. It was to be explained as a product of their adaptation to the extraordinarily varied ecology of the vast territory of Australia; each sub-population had adjusted to its particular niche. Distinctive differences among Aboriginal groups had developed when geological changes created barriers that “isolated [them] from one another for long periods of time.” Aboriginal populations adapted to their local conditions in fashions that were not so much determined by these conditions as compatible with them, each population developing skills in the fabrication of particular tools and other artifacts. Eventually, the Aborigines joined in wide-ranging trade networks to exchange their distinctive goods (as well as implements introduced by white settlers). Why was it critical to establish that the Australia’s Aborigines were a single people? The Aborigines’ ability to survive under many conditions denoted their enormous inherent potential – which made possible further adaptation in the future. Their diversity represented expression of “nascent possibilities of development along many varied lines,” and their “capacity and mental outlook” should not be “underestimate[d].”43 In sum, Spencer’s orthodox Darwinism (quite different

40

Native Tribes, 26. And see Baldwin Spencer, President, “Inaugural Address,” Australasian Association for the Advancement of Science, Report of the Fifteenth Meeting of the Australasian Association for the Advancement of Science. Hobart Meeting [actually held in Melbourne], January 1921 (Melbourne: AAAS, 1921), liii-lxxxix, esp. lxvi. 41 Across Australia, vol. 1, 123, 188–9; vol. 2, 307–8. 42 Native Tribes, 46; and see 56, 96–100, 196, 381. 43 Northern Tribes, 16; Native Tribes, 117, 596; Spencer, “Inaugural Address,” lxvii, lxxiii. And see Native Tribes, esp. 1–9, 575, 587–8.

96

H. Kuklick

from the stereotypical social Darwinism that some have imputed to him) contradicted much conventional white settler wisdom: Spencer and Gillen repudiated the widespread fears that European migrants to Australia would degenerate, even in the parts of the country that were least like Europe, its tropical regions; and they suggested that Aborigines could learn to live in the colonists’ social world – and would produce healthy children when they formed unions with Europeans.44 (It is worth noting that in his official capacity, Gillen was an energetic defender of Aborigines’ rights and welfare.)45 However we may feel now about the political significance of advocacy of assimilation, this position represented a distinctly liberal political view in Spencer and Gillen’s day. Spencer and Gillen – and the anthropologists with whom they agreed – certainly did not wish to argue that there were no qualitative differences among cultures. But their approach conduced to the disaggregation of nature and culture. To Malinowski, for example, it seemed obvious that populations’ social behavior could change rapidly, while their biological characteristics remained stable.46 Moreover, it seemed clear that cultural evolutionary change did not take the orderly course that nineteenth-century anthropologists had imagined. As Spencer observed, “there [wa]s no such thing as an all-around ‘primitive’ tribe.”47 The appropriate way to understand “the essence of evolution,” Malinowski said, was not as “a sequence of different forms changing one into another, but [as] a better adaptation of an institution to its function.”48 His anthropological research earned Spencer international fame – as well as a knighthood, conferred in 1916. But his work with Gillen influenced anthropologists worldwide in ways the men could not have anticipated (and to some extent deplored). It figured in an international controversy over a general phenomenon – totemism, or behavior based on some putative special connection between a group of people and a feature of the natural world, an animal or a plant. Because Spencer and Gillen judged that Aborigines had had a distinctly “Australian form of totemism,” they objected that many of the theories putatively derived from their evidence were “quite

44 On fears that Europeans would degenerate in Australia, see Richard White, Inventing Australia. Images and Identity 1688–1980 (St. Leonards, N.S.W.: Allen and Unwin, 1981), 70–71. 45 For example, in one notable instance, in 1891, Gillen attempted to hold a white policeman liable for the murder of an Aborigine; see John Mulvaney, ‘F. J. Gillen’s Life and Times’, in John Mulvaney, Howard Morphy, and Alison Petch, eds., ‘My Dear Spencer’. The Letters of F. J. Gillen to Baldwin Spencer (Melbourne: University of Melbourne Press, 1997), esp. 6–7. 46 See Nicholas Peterson, “Studying man and man’s nature: the history of the institutionalization of Aboriginal anthropology,” Australian Aboriginal Studies 7, 2 (1990), 7. 47 Baldwin Spencer to J. G. Frazer, 7 June 1903, in R. R. Marett and T. K. Penniman, eds., Spencer’s Scientific Correspondence with Sir J. G. Frazer and Others (Oxford: Oxford University Press, 1932), 93. 48 Bronislaw Malinowski, “Anthropology,” Volume 1 of the three supplementary volumes published for the 13th edition of the Encyclopaedia Britannica (London and New York: The Encyclopaedia Britannica Company, 1926), 133.


97

inapplicable to our tribes.”49 I must stress that virtually all of the social anthropologists in the British sphere of intellectual influence who came to professional maturity around 1920 and afterwards embraced a conceptual framework that derived from studies that interpreted cultural variation in bio-geographical terms – and that the British social anthropology developed after World War I arguably had an international influence greater than any other national variant of the discipline. Many anthropologists outside Britain did not take an approach to cultural analysis that derived from field research comparable to Spencer and Gillen’s, however.50 Indeed, in the United States, where anthropology came under the leadership of the German-born and –trained Franz Boas in the early twentieth century, bio-geographical reasoning was repudiated just as Boas’s critique of evolutionism in the style of Morgan became received wisdom. Although Boas allowed that geographical isolation could preserve a population’s “older type” of culture, his and his students’ approach to anthropology was fundamentally historical – with an emphasis on situational peculiarities and a near-hostility to generalization; Boasians’ judged that geographical factors explained behavior only “in trivial and shallow ways,” and that people often did things “in spite of” geographical conditions.51 One might argue that Spencer and Gillen’s analytic framework was practically irrelevant to the international debate. Nevertheless, the anthropological argument provoked by the publication in 1899 of Native Tribes of Central Australia and – just as important – the second edition of J. G. Frazer’s The Golden Bough, published in 1900 and featuring Spencer and Gillen’s material, suggests that the decline of the nineteenth-century, unilinear conceptualization of cultural evolution was over-determined. Frazer brokered the publication of Native Tribes with his publisher, Macmillan, not least because he intended to turn its evidence to his purposes (this was a recurrent theme in Frazer’s dealings with his publisher). And as a person with considerable stature in the world of anthropology in his day (no matter what his legacy is in ours), Frazer was able to shape the totemism debate that followed. In essence, Frazer expected that Spencer and Gillen’s data would prove of vital importance in answering fundamental questions of evolutionary anthropology: One, was it possible to specify the characteristics of each of the stages through

49

See Gillen to Spencer, 17 November 1902, in Mulvaney, Morphy and Petch, 419, 416. Similar assumptions informed the Cambridge Anthropological Expedition to Torres Straits of 1898, organized by A. C. Haddon, a Cambridge-trained zoologist whose career was much like Spencer’s (he came second in the competition to become Melbourne’s foundation professor of biology, for example), and who corresponded with Spencer and promoted his work. Virtually all British anthropologists until World War II were somehow professional progeny of the Torres Straits Expedition; conspicuous among these were students of two members of the expedition, C. G. Seligman and W. H. R. Rivers, respectively Bronislaw Malinowski and A. R. RadcliffeBrown. I describe the biogeographical conceptualization of the expedition in Kuklick, 1996. 51 Franz Boas, “Arctic Exploration and Its Object,” Popular Science Monthly 22 (1885): 78–81; Franz Boas, “Ethnological Problems in Canada,” Journal of the Royal Anthropological Institute 40 (1910): 530, 531. The generalizations are Alexander Lesser’s; see his “Franz Boas,” International Encyclopedia of the Social Sciences, David Sills, ed. (New York: Macmillan and The Free Press, 1968), II, p. 101. 50

98

H. Kuklick

which human populations passed during the course of their progress from savagery to civilization? Two (the most important question for Frazer), what were the origins of truly spiritual religion and monogamous marriage, the signal accomplishments of high civilization?52 But the prevailing view of social theorists everywhere came to be that evolutionists’ problems defied solution. It seemed “impossible” to extrapolate from “the simplest social state known at present” to an “absolute beginning,” as E´mile Durkheim observed in The Elementary Forms of Religious Life (subtitled The Totemic System in Australia), now generally regarded as his most important book and unquestionably the most enduring product of the totemism controversy, which relied heavily on Spencer and Gillen’s data – and rejected Frazer’s interpretation of them.53 Moreover, virtually any account could be dismissed with the charge that was made against Native Tribes – that it reported the behavior of people whose authentic culture had been corrupted by contact with Europeans, precluding the possibility that the people represented genuine specimens of any cultural stage.54 And social evolutionists’ ideal types were belied by reports from the field. For example, evidence provided by the German missionary Carl Strehlow, who lived with and also wrote about the Central Australian Arrernte, convinced a number of persons, including the British Andrew Lang and the Austrian Wilhelm Schmidt, that there was no association between superior spirituality and material progress; humans in the “lowest known grades of savagery,” said Lang, were capable of beliefs “as monotheistic as some Christians.”55 The German sociologist Max Weber concluded that the phenomenon of totemism was evidently neither universal nor associated with a specific pattern of development.56 Just as important, as the Boasian John Swanton observed in 1906, those who debated the nature of totemism not only generated conflicting theories but were also incapable of adopting shared definitions of the terms “totem” and “totemism,” as well as of practices that might be associated with totemism, such as “witchcraft,” “magic”, and “fetishism.”57 Such confusion made arguments circular. Did totem ceremonies – intended to increase the supply of the specific animal or plant with which persons identified – represent the very earliest form of religion? Or, did these

52

See, e.g., J. G. Frazer to George Macmillan, 23 August 1897, British Library, Macmillan Archive, Add.MS 55134. 53 ´ E. Durkheim, The Elementary Forms of Religious Life, translated by Karen E. Fields (New York: Basic Books, 1995 [orig. 1912]), 7. 54 See, e.g., A. A. Goldenweiser, ‘Reconstructions from Survivals in West Australia’, AA n.s. 18 (1916): 476–8. 55 Quoted in G. W. Stocking, Jr., After Tylor (Madison: University of Wisconsin Press, 1995), 59. 56 Max Weber, Sociology of Religion, posthumously published in 1925, cited in Brian Morris, Anthropological Studies of Religion (New York: Cambridge University Press, 1987), 71. 57 J. R. Swanton, Review of Lectures on the Early History of the Kingship by J. G. Frazer, American Anthropologist (subsequently AA) n.s. 8 (1906): 157–160; and Review of The Secret of the Totem by Andrew Lang, AA n.s. 8 (1906): 160–165. Swanton was not alone in this critique. See also, e.g., A. R. Brown (later Radcliffe-Brown), “The Definition of Totemism,” Anthropos 9 (1914): 622–30.


99

ceremonies constitute efforts to perform “magic,” rather than being acts of submission to the will of some sort of supernatural being?58 Resolution of these questions required procedural consensus that anthropologists could not effect. The Boasians’ critique of the issues at stake in the totemism debate represented dismissal of the entire nineteenth-century social evolutionist paradigm: totemism was not associated with the changes that denoted progress to evolutionists – such as the shift from kinship structured by ties to mothers to patrilineal organization, the specification of marriage regulations that prohibited unions between close kin (however close kin were defined in a given society), the differentiation of social roles and the elaboration of class hierarchy, and the development of religion in which worshippers submitted to an omnipotent god. Nor was there a consistent pattern of change: because peoples acquired traits by diffusion as well independent invention, societies often incorporated elements that evolutionists had imagined were irreconcilable.59 In sum: the repudiation of social evolutionary theory of the nineteenth century variety was over-determined. Not least because of the expansion of colonial power at the end of the nineteenth century, some exotic places became relatively safe places for Europeans to spend sustained periods in residence; and these were the areas from which came the evidence that seemed most significant to anthropologists. Anthropological fieldwork framed by a Darwinian biographical approach proved extremely important in changing the discipline, (perhaps paradoxically) leading to a thorough separation of cultural from biological anthropology. Nevertheless, biogeographical analysis was not required to discredit linear models of human development. Abundant evidence became available that served to suggest that evolutionists’ tidy scheme of successive stages of evolutionary progress did not correspond to observed behavior. Socio-cultural anthropology remained focused on non-Western peoples, but the rationale for studying them ceased to be that their behavior revealed patterns of evolutionary development (unless evolution meant only successful adaptation to circumstances). Instead, simple societies were understood as simple organisms in which it was relatively easy to observe the enduring structures of social life that were essential to all those societies on earth that managed to survive. Not until the 1980s would evolutionary approaches to the analysis of culture that were advertised as authentically Darwinian seem respectable to more than a distinct minority of socio-cultural anthropologists – but that is a development that may be most significant as evidence of the rise of conceptual pluralism in anthropology, and is, as such, another story.60

58 See, e.g., J. G. Frazer, “On Some Ceremonies of the Central Australian Tribes,” Report of the Eighth Meeting of the Australasian Association for the Advancement of Science. Melbourne: 1900 (Melbourne: AAAS, 1901), 312–321; Native Tribes, 170. 59 See especially, John R. Swanton, “The social and the emotional element in totemism,” Anthropos 9 (1914): 288–299; Alexander A. Goldenweiser, “Totemism, An Analytical Study,” Journal of American Folk-Lore 23 (1910): 178–293. 60 For a survey, see William H. Dunham, “Advances in Evolutionary Culture Theory,” Annual Review of Anthropology 19 (1990): 187–210.

100

H. Kuklick

Published Sources 1. Brantlinger P (2003) Dark vanishings. Cornell University Press, Ithaca 2. Brown (later Radcliffe-Brown) AR (1914) The definition of totemism. Anthropos 9:622–630 3. Boas F (1885) Arctic exploration and its object. Pop Sci Monthly 22:78–81 4. Boas F (1910) Ethnological problems in Canada. J Roy Anthropol Inst 40:530–531 5. Burkhardt R Jr (2005) Patterns of behavior. University of Chicago Press, Chicago 6. Burrow JW (1963) Evolution and anthropology in the 1860’s: the anthropological society of London, 1863–71. Victorian Stud 7:137–154 7. Burrow JW (1966) Evolution and society. Cambridge University Press, Cambridge 8. Darnell R (2008) North American traditions in anthropology. In: Kuklick H (ed) A new history of anthropology. Blackwell, Oxford/Malden, pp 35–51 9. Darwin C (1874) The descent of man, 2nd edn. AL Burt, New York 10. Dunham WH (1990) Advances in evolutionary culture theory. Annu Rev Anthropol 19: 187–210 11. Durkheim E´ (1995 [orig 1912]) The elementary forms of religious life (trans: Fields KE). Basic Books, New York 12. Evans AD (2010) Anthropology at war: world war I and the science of race in Germany. University of Chicago Press, Chicago 13. Frazer JG (1899) The origin of totemism. Fortnightly Rev 71(647–665):647–665, 835–851 14. Frazer JG (1901) On some ceremonies of the central Australian tribes. Report of the eighth meeting of the Australasian association for the advancement of science, Melbourne: 1900. AAAS, Melbourne, pp. 312–321 15. Goldenweiser AA (1910) Totemism: an analytical study. J Am Folk-Lore 23:178–293 16. Goldenweiser AA (1916) Reconstructions from survivals in west Australia. AA ns 18:476–478 17. Haddon AC (1890) Manners and customs of the Torres Straits Islanders. Nature 42:637–642 18. Haddon AC (1910) History of anthropology. GP Putnam’s Sons, London 19. Haeckel E (1913) Fifty years of anthropology. N Am Rev 198(696):609–616 20. Hoffman DM, Gardner AM (eds) (2006) Dispatches from the field. Waveland Press, Long Grove 21. Kuklick H (1991) The savage within: the social history of British anthropology, 1885–1845. Cambridge University Press, New York 22. Kuklick H (1996) Islands in the Pacific: Darwinian biogeography and British anthropology. Am Ethnol 23:611–638 23. Kuklick H (2006) ‘Humanity in the chrysalis stage’: indigenous Australians in the anthropological imagination, 1899–1926. Br J Hist Sci 39:535–568 24. Kuklick H (2011) Personal equations: reflections on the history of fieldwork, with special reference to sociocultural anthropology. ISIS 102:1–33 25. Lanzoni S (2009) Sympathy in mind (1876–1900). J Hist Ideas 70:265–287 26. Lesser A (1968) Franz Boas. In: Sills D (ed) International encyclopedia of the social sciences. Macmillan/The Free Press, New York 27. Lubbock J (1872) On the development of relationships. J Anthropol Inst 1:1–29 28. Lubbock J (1885) On the customs of marriage and systems of relationship among the Australians. J Anthropol Inst 14:292–300 29. Marett RR, Penniman TK (1932) Spencer’s scientific correspondence with sir J. G. Frazer and Others. Oxford University Press, Oxford 30. Malgrave HF (1985) Gustav Klemm and Gottfried Semper: the meeting of ethnological and architectural theory. Anthropol Aesthet 9:68–79 31. Malinowski B (1913) Review of across Australia by Baldwin Spencer and F. J. Gillen. FolkLore 24:278 32. Malinowski B (1926) Anthropology in volume one of the three supplementary volumes published for the 13th edition of the Encyclopaedia Britannica. The Encyclopaedia Britannica Company, London/New York


101

33. McGregor R (1997) Imagined destinies: aboriginal Australians and the doomed race theory, 1880–1939. University of Melbourne Press, Melbourne 34. Morris B (1987) Anthropological studies of religion. Cambridge University Press, New York 35. Mulvaney DJ, Calaby JH (1985) So much that is new: Baldwin Spencer, 1860–1920. Carlton, Victoria 36. Mulvaney J, Morphy H, Petch A (1997) My dear Spencer’: the letters of F. J. Gillen to Baldwin Spencer. University of Melbourne Press, Melbourne 37. Peterson N (1990) Studying man and man’s nature: the history of the institutionalization of aboriginal anthropology. Aust Aboriginal Stud 7:2 38. Richards RJ (2008) The tragic sense of life. University of Chicago Press, Chicago 39. Rivers WHR (1913) Report on anthropological research outside America. In: Rivers WHR, Jenks AE, Morley SG (eds) The present constitution and future needs of the science of anthropology. Carnegie Institution of Washington, Washington, DC, pp 5–28 40. Sibeud E (2008) The metamorphosis of ethnology in France, 1839–1930. In: Kuklick H (ed) A new history of anthropology. Blackwell, Oxford, pp 96–110 41. Spencer B (1921) Presidential inaugural address. Australasian Association for the Advancement of Science, Report of the fifteenth meeting of the Australasian Association for the Advancement of Science. Hobart meeting (actually held in Melbourne), Jan 1921. Melbourne, liii–lxxxix 42. Spencer B, Gillen FJ (1899) Native tribes of central Australia. Macmillan, London 43. Spencer B, Gillen FJ (1904) The northern tribes of central Australia. Macmillan, London 44. Spencer B, Gillen FJ (1912) Across Australia. Macmillan, London 45. Spencer B, Gillen FJ (1927) The Arunta. Macmillan, London 46. Stafford RA (1990) Annexing the landscapes of the past: British imperial geology in the nineteenth century. In: MacKenzie JM (ed) Imperialism and the natural world. Manchester University Press, Manchester, pp 67–89 47. Stern BJ (1928) Lewis Henry Morgan: American ethnologist. Soc Forces 6:344–357 48. Stocking GW Jr (1971) What’s in a name? The origins of the Royal Anthropological Institute, 1837–1871. Man ns 6:369–390 49. Stocking GW Jr, Tylor A (1995) University of Wisconsin Press, Madison 50. Swanton JR (1906) Review of lectures on the early history of the kingship by JG Frazer. American anthropologist (subsequently AA) n.s. 8: 157–160; and Review of the secret of the totem by Andrew Lang, AA n.s. 8(1906): 160–165 51. Swanton JR (1914) The social and the emotional element in totemism. Anthropos 9: 288–299 52. Wallace AR (1864) The origin of human races and the antiquity of man deduced from the theory of ‘natural selection’. J Anthropol Soc London 2:clviii–clxxxvii 53. White R (1981) Inventing Australia: images and identity 1688–1980. Allen and Unwin, St Leonards 54. Young MW (2004) Malinowski: odyssey of an anthropologist, 1884–1920. Yale University Press, New Haven

Archival Sources Malinowski to Atlee Hunt, Secretary, Department of External Affairs, 28 April 1915, and Hunt to Malinowski, 4 May 1915, Yale University Archives, MS 19, Box 4 Bronislaw Malinowski to C. G. Seligman, 4 May 1915, Malinowski papers, file 27/3, London School of Economics Baldwin Spencer to W. E. Roth, 30 Jan 1903, Spencer papers, Pitt Rivers Museum, Oxford University. Box 1A

102

H. Kuklick

A. C. Haddon to Baldwin Spencer, 5 May 1902, in the Spencer papers, Pitt Rivers Museum, Oxford (subsequently, S P), Box 1 Avebury papers, British Library P. M. Byrne to Baldwin Spencer, 18 April 1895, S P, Box 1A J. G. Frazer to George Macmillan, 23 Aug 1897, British Library, Macmillan Archive, Add.MS 55134

The Concept of Evolution in Linguistics Manfred Bierwisch

Abstract Language has been viewed for a long time as a field of evolution where new things originate through variation. In the early nineteenth century, important insights were reached within this still pre-Darwinian tradition by historical-comparative linguistics. The laws of sound change and vowel shift discovered by Grimm and others are essentially valid today, although development by then was largely considered as loss and deprivation. A strictly Darwinian view of language change was advocated in 1863 by Schleicher, who considered languages as organisms to which biological principles of adaptation and survival were to be applied directly. The difficulty to reconcile insights of language development with principles of biological evolution was the requirement to construe languages as species, the genetic information of which is subject to random variation and completely independent of reproduction of their members. On closer inspection, the range of possible language variation is provided by the human language faculty, and the domain of competition for reproduction is the actual use of language. This leads to two competing views of language change. A Lamarckian view considers variants as the product of functional needs, subsequently inherited by the language used, while a strictly Darwinian view considers variants as random products of the language faculty which do survive or not according to conditions of language use. Although in many, notably lexical, cases the functional origin of variants is beyond doubt, the Darwinian nature of much language change is still attested by properties that cannot be due to functional requirements, but emerge from traits of the language capacity and are not suppressed by functional needs. Language change must thus be considered as evolution of mixed nature. A short epilogue raises the question whether this type of mixed evolution could be the general nature of human history and cultural development. Skepticism is indicated for two reasons. First, the language faculty is domain specific, its conditions cannot be generalized to arbitrary fields. Second,

M. Bierwisch (*) Humboldt-Universit€at zu Berlin, Berlin, Germany e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_7, # Springer-Verlag Italia 2012

103

104

M. Bierwisch

there is no reason to assume a universal cultural capacity from which action patterns randomly arise.

1 The Background of the Humanities Change per se does not constitute evolution. In this paper, we will use the term “evolution” to describe change that gives rise to something that did not previously exist. What evolution produces need not always represent a higher stage of development, nor will it necessarily create an independent entity either in and of itself or by taxonomic definition. What evolution should always represent, however, is a genesis of differentiable states or entities. This definition allows for the existence of various types of evolution, depending on what sort of processes are involved. There is, of course, the evolution of biological species, but we can also speak of the evolution of galaxies, of stars and planets, of geological formations and chemical elements, or even of institutions, communities and technologies. With respect to linguistics, the phenomenon of evolution is evident in at least three different areas: phylogenesis (the development of the language faculty in man), ontogenesis (the development of the internal language in an individual), and language change (the emergence of the various languages and how they change over time). That these phenomena are very different in their natures is obvious. Less obvious, however, is how they relate to and influence one another. As a species-specific characteristic in the strict sense, the phylogenesis of language is one facet of the phylogenesis of homo sapiens and as such a subject of study for evolutionary biologists. But it is also a matter for linguists, since explaining the biological prerequisites for and the origination of the language faculty is not possible without an understanding of the specific structure of human language. In strict linguistic academia, researchers examine variation and development primarily with respect to the phenomenon of language change and hence to the emergence of new languages and dialects. One important question facing researchers is how the development of languages is linked through language acquisition with the conditions of the language faculty. Man has since antiquity been aware of the fact that languages change, that their elements and rules undergo alteration and development. For many years, however, it was only possible to make isolated observations and in some cases develop speculative theories, but these can be left aside here. It was not until the early nineteenth century with the realization of the cultural and historical importance of Sanskrit and the emergence of comparative historical linguistics that chance observations were replaced by systematic study in the works of Rask, Bopp, Grimm and others. The systematic understanding of the historical relationships between the Indo-European languages and the fundamental concept of sound shift that allowed for an explanation of these relationships led to the theory of the IndoEuropean language family and concurrently to the far-reaching theory of systematic language change. This theory allowed scientists to comprehend the existing

The Concept of Evolution in Linguistics

105

phonetic and grammatical forms of the various languages as the result of tangible processes and then to retrace these processes to identify precursors to existing forms. Thus was born a fundamental concept for describing the principles of language development. Jacob Grimm summarized one key discovery as follows: The entire twofold sound shift, which has momentous consequences for the history of language and the rigor of etymology, can be so expressed in a table: Greek Gothic Old High German

P B PH FPB BFP

T D TH TH T D DZT

K G CH ... K G G CH K

(Jacob Grimm, Deutsche Grammatik, Part 1, [3], p. 584) In other words, language development is determined by processes of the type: P ¼¼¼ > PH,

T ¼¼¼ > TH,

K ¼¼¼ > KH, etc.

or, more generally: Stop ¼¼¼ > Spirant Media ¼¼¼> Tenuis Spirant ¼¼¼> Media This grand scheme was fully confirmed by later supplementary work and the incorporation of revealing details and was further generalized to cover the entire Indo-European language family. Processes of this kind that lay claim to exceptionless validity were later considered to represent phonetic laws, which were explained and justified based on the workings of the human speech organs. Initially, though, language change was deemed a phenomenon residing solely in the realm of intellectual history, fully disconnected from biological evolution or any other processes in the natural environment. In the full spirit of the romantic era, Jacob Grimm viewed language development basically as a process of decay, as the slipping away of a hereditary treasure. This even applied to sound change in itself, which he interpreted as nothing more than a descent to a lower condition: For just as Old High German has sunk one step down from the Gothic in all three grades, Gothic itself had already deviated by one step from the Latin (Greek, Sanskrit). (Ibid.)

Wilhelm von Humboldt likewise viewed the development of language as an intellectual process that was continuously robbing us of a rich inheritance. About language, he wrote: Its nature is to pursue a progressive path of development, under the influence of the mental power, at any time, of its speakers. In this progress there naturally arises two periods, which must be sharply distinguished, the one where the sound-making impulse of the language is still in a state of growth and lively activity; the other where, after completed shaping at least of the outer speech-form, a seeming halt occurs, and there follows a visible decline in that creative sensuous impulse. ([5], Collected Works, 7, p. 160)

For both Humboldt and Grimm, one of the most prominent symptoms of such decay was seen in the gradual disappearance of inflected forms. But of course the obvious changes in language and even in language types that they explicitly

106

M. Bierwisch

examined in their works was not considered a phenomenon that could in any way be linked to the evolution of biological species.

2 Evolutionary Linguistics: The Initial Approach Thirty years later, Jena-based Slavist and linguist August Schleicher did make precisely this link in an initial approach to linguistic Darwinism set forth in a highly programmatic “open letter” that was inspired by Ernst Haeckel and entitled Die Darwinsche Theorie und die Sprachwissenschaft [8]. In the English translation published in 1869 under the title Darwinism Tested by the Science of Language, Schleicher states: Languages are organisms of nature; they have never been directed by the will of man; they rose, and developed themselves according to definite laws; they grew old, and died out. They, too, are subject to that series of phenomena which we embrace under the name of “life”. The science of language is consequently a natural science; its method is generally altogether the same as that of any other natural science.

Although in a note Schleicher excludes philology as a historical discipline, he does state the following: The rules now, which Darwin lays down with regard to the species of animals and plants, are equally applicable to the organisms of language, that is to say, as far as the main features are concerned. [. . .] What Darwin now maintains with regard to the variation of the species in the course of time, through which – when it does not reveal itself in all individuals in like manner and to the same extent – one form grows into several distinct other forms by a process of continual repetition, that has been long and generally recognised in its application to the organisms of speech. Such languages as we would call, in the terminology of the botanist or zoologist, the species of a genus, are for us the daughters of one stock-language, whence they proceeded by gradual variation. Where we are sufficiently familiar with any particular family of speech we draw up a genealogical table similar to the one which Darwin attempted for the species of animals and plants.

Building on the discoveries of comparative historical research, Schleicher uses a rigid and somewhat speculative genealogical tree to depict the relationships within the Indo-European language family as known to that time. Though he firmly believed that a proto-language formed the common “trunk” of the family tree, he nonetheless skeptically posed the question: But how stands the fact with the creation of the genera? That is to say, in the glossologist’s phraseology, with the self-development of those mother-languages which have given birth to the different families of speech? . . . do those parent idioms again descend from a common stock, and all these in the end from one single primitive form of speech? [. . .] This question might be decided with greater certainty if we had examined the primitive form of a good many more families of speech . . . than we have done. Above all, the varieties of those special families of speech, which have been carefully examined, are so great and of such a nature, as to render it impossible for any unbiased mind to believe in a common origin.


107

Based on the approach derived from these considerations, Schleicher pursued the study of the parallel development of species and languages: Now we observe during historical periods how species and genera of speech disappear, and how others extend themselves at the expense of the dead. I only remind you, by way of illustration, of the spread of the Indo-Germanic family and the decay of the American languages. In the earlier times, when the languages were still spoken by comparatively weak populations, this dying out of forms of speech was, no doubt, of much more frequent occurrence [. . .] It is very possible that many more species of speech perished during the course of that time than the number of those which have prolonged their existence up to the present day. This explains the possibility of so great an extension as for instance that of the Indo-Germanic, the Finnic, the Malay and South-African families, which, over a large territory, branched off into such a multitude of directions. A similar process is assumed by Darwin with regard to the animal and vegetable creation; that is what he calls “the struggle for life”.

Schleicher’s highly autonomous parallelization of biological and linguistic evolution was based on the analogy between languages and biological species, an analogy with elicits interesting insights but to a still greater degree reveals unresolved problems. The similarity between languages and species at first appears plausible and unproblematic. Like a species, a language manifests itself within a group of individuals (a population), with which it grows, migrates or dies out. But unlike with a species, the extinction of a language does not necessarily mean the demise of its population. The speakers of one language can continue to survive speaking an altered language, whereas the members of one species cannot continue to survive as the representative of another. Related to this finding are two essential differences that are concealed by Schleicher’s equating of languages to natural organisms. Firstly, though neither Darwin nor Schleicher could have been aware of the true nature of the changes that give rise to new species or languages, such knowledge is not necessary to realize that the main issue lies somewhere else altogether, namely that the traits of a new species are transmitted to the individuals of the next generation by inheritance. This was Darwin’s basic thesis. In contrast to biological evolution, however, the traits of a new language are not inherited by members of the species; but rather must be acquired. The second difference, directly related to the first, is the fact that the core claim of evolutionary theory, which states that successful traits will survive and less successful ones will die out, found no apparent counterpart in the process of language development, regardless of whether such development was seen as a process of enrichment or decay. For it is nowhere evident how changes in language characteristics could be of any advantage in human reproduction, nor did Schleicher ever touch upon this subject. This problem is exacerbated by the fact that Schleicher not only compares language with species but also with organisms, for example when he states that the . . . roots are, as it were, the simple language-cells yet unprovided with separate organs for the functions of verb, noun, etc., and these functions (the grammatical relationships) are yet as undifferentiated as breathing and digestion are in single-cell organisms or in the blastocysts of higher life forms.

108

M. Bierwisch

Even if only meant as a metaphor, this statement does suggest a comparison between language units and organic elements that is invalid with respect to both how such units and elements come into being and to the function they perform. There may indeed exist contexts where organic stem cells could be compared with unspecialized grammatical roots, but the evolution of linguistic elements cannot be grasped in this way. Based upon an impressive, systematic background of insights into the structure and history of natural languages, Schleicher’s open letter represents a remarkable surge forward in the development of linguistics and other disciplines. Nonetheless, this work did not determine the course for the mainstream of linguistics. This fact was doubtless due more to the growing alienation between the natural sciences and the humanities than to the yet lacking genetic understanding of evolutionary processes. In light of today’s knowledge, however, we are now called upon to revisit and reexamine Schleicher’s theories. The task at hand is to investigate whether and in what manner the concept of evolution that applies to biology can also be applied to languages (and hence to other sociocultural institutions). To this end, it is helpful to first recapitulate the most important terms and concepts.

3 Evolution and Language: Essential Definitions Teleonomy, or purposefulness, deriving from evolution (this was the decisive insight made by Darwin and Wallace) is in principle the result of those random variations that subsequently prove to be advantageous for the organism and its selfpropagation. In contrast to the earlier Lamarckian theory of evolution, a teleonomic trait is thus not the result of adaptation or goal-oriented (teleological) change, but rather comes about through selection from randomly arising possibilities. This means that the traits available for transmission to the next generation appear at random and without any control. Only upon confrontation with the natural environment will any purposeful advantage of a trait be revealed, and this advantage will ultimately lead to the trait being inherited by offspring. In a population where individuals reproduce themselves and their constant traits, the following two factors are decisive for the concept of evolution: (a) The existence of a repertoire of random variations of traits within a population. (b) The selection of those variants that succeed in the environment and in reproduction. Geneticists and molecular biologists today have a step-by-step understanding of the details surrounding these factors and the relationship between them. To a large extent, they have been able to explain the interaction of variation and selection (a simple given for Darwin) in accordance with the laws of biophysics and behavioral regulation. Of primary essence here is an understanding of the dichotomy between the genotype as the sum of an individual’s genetic information, the


109

variation of which is the subject of factor (a), and the phenotype that is expressed in the organism and which is the object of selection in factor (b). The two factors are therefore not only subjected to different effect mechanisms but also belong to completely separate spheres of causality. The causes that drive variation and which exert their effects in the genome (the entirety of an organism’s hereditary information) are unrelated to the conditions under which an organism’s characteristics are tested and selected. Even more important is the fact that the genotype and the phenotype are governed by fully dichotomous types of natural laws. In oversimplified terms, there is essentially no connection between the microphysical conditions that impact the genome and the macrophysical processes that shape the phenotype. The link between these two spheres is established by the organism’s hereditary information in accordance with the principles of genetic control. Generalized across the population as a whole, the process of selection will in time effect the spread of favorable traits in the population due to the reproduction of successful variants. Years of subsequent research have enhanced and enriched this basic scheme of variation and selection by incorporating a number of different factors. Although these factors do not threaten the fundamental theory of evolution, they certainly must be taken into consideration when evaluating analogies between biological and linguistic evolution. For example, the concept of adaptive selection, whereby only advantageous variants enter the hereditary line, has been complemented by the idea of “exaptive” selection, which also accepts characteristics that are neutral, i.e. not disadvantageous, but which may very well assume an adaptive function under changing conditions. This may explain, for example, why various decorative traits have been incorporated into the hereditary material of many different species. Further, there has been repeated speculation concerning the existence of internal or structural selectors that act on the genetic information level to influence the formation of variants, seemingly narrowing the gap between the phenotype and the genotype. These structural selectors are, however, probably better understood as factors that control the creation of random variants, thereby acting as regulators for purely stochastic mutations and making these mutations random with respect to the phenotype but not necessarily with respect to the structure of the hereditary information. Finally, Wilson and Dawkins have shown with their concept of sociobiology that the conditions for variance and invariance in a species should be understood as the tendency towards genome constancy, i.e. that the selection to which the phenotype is subjected serves the self-assertion of the genotype. This highly successful concept of genome identity preservation has spotlighted an aspect that is not relevant in classic evolutionary theory. While selection was initially only seen with regard to the reproduction conditions surrounding the phenotype, sociobiology equates reproductive success with the constancy or self-assertion of the genome. From this perspective, the selection of variants – which indeed runs counter to such constancy – is considered to be minimal change under altered environmental conditions. Of course, the genome has no intentions. It is not goal-oriented. On the contrary, it works causally, like an actor, with the effect of maximum constancy

110

M. Bierwisch

of self-replication. The heteronomy of the genome and the organism remain unchanged: the constancy and variation of the genetic information are not products of the causal relationships associated with the phenotype. Besides anatomical and functional characteristics, other genetically conditioned and inherited traits include biologically determined, species-specific behavioral patterns and their underlying organic conditions. Already given central prominence by ethnologists, this notion is gaining importance in the field of sociobiology as well. It also covers what are known as epigenetic developments, i.e. dispositions and behaviors whose framework is biologically fixed but which only find expression during ontogeny under the influence of individual experiences. Examples include walking upright in humans or song learning among birds. Human language, too, would naturally fit into this category. So what do these realizations about evolution mean with respect to language? Here, we must clearly distinguish between three aspects that linguists have discerned since de Saussure [2] as faculte´ de langage, langue and parole. The same distinctions are essentially made by Chomsky [1] using the terms faculty of language, internal language and external language. 1. Faculty of language is a characteristic specific to homo sapiens and is itself a decisive product of evolution that emerged through mutation and selection and which must be anchored in the genome. The only controversy here surrounds the questions of how specific and differentiable this faculty is compared with other, more general dispositions, and whether it grew out of a complex series of developmental stages or emerged in a single evolutionary leap. Whatever the case, the all-important outcome is the ability to create and iteratively combine symbols, i.e. to make use of complex, convention-governed signs that link structured signals to cognitively organized meanings. Of all the abilities that evolution has endowed upon us, the faculty of language is without a doubt the most characteristically human. 2. Building on the faculty of language, the internal language develops in a largely spontaneous process as a complex structure within the brain of every normallyconstituted speaker. The internal language encompasses the entire range of symbols and combination rules that are needed to construct and understand utterances. The internal language acquired by the members of a language community is the shared basis of that community and can vary, within narrow limits, to allow for different elements and combination rules. 3. By external language we mean the structured behavioral habits that the internal language makes possible, i.e. the concrete space–time actions in a population united by a given language, or, in other words, the speech acts and their manifestations. To our knowledge, the faculty of language is a universal, species-specific and biologically hardwired disposition, the foundation of which is anchored in the human genome. Among different populations, this universal disposition finds its expression through varying and changing systems of internal and external language. Taken together, internal and external language form two completely different yet


111

equally essential aspects of what August Schleicher envisioned as the linguistic counterpart to the biological species. Internal and external language are asymmetrically linked, representing the structure and the execution of linguistic utterances, borne by the members of a language community, that is, the individuals without whom there would be no internal language or adherence to its rules. Nonetheless we cannot – as noted above – equate the speaker of a language with an individual of a species. While speakers of a language have the required ability, individuals of a species are representatives of that species. A speaker belongs to a species, or even to an ethnic group, but certainly not to language. (You can acquire a different language but not a different ethnic group.) The difference drawn here is not one of definition but rather of category, and its significance is greater than Schleicher was aware. But despite the fundamental difference between languages and biological species, the relationship between internal language and language behavior does reveal some parallels with the genotype–phenotype relationship. Although the transfer process through which the DNA structure determines the makeup and behavior of an organism has nothing to do with the way that the internal language structures linguistic utterances, the internal language does enable and control language behavior just as the genotype determines the phenotype. As such, the internal language would be comparable to the genome, with one crucial difference regarding how such determination works: the structures and variants of the genome are in no way subject to the principles of the phenotype, while internal and external language intermesh with one another directly and are characterized in the same terms. To put it briefly, the genotype and the phenotype are subjected to different causalities within completely separate phenomenal spaces, while internal and external language, though also determined by different causalities, belong to the same domain of experience. What do these complex correspondences and differences say about the validity and fruitfulness of applying evolutionary concepts to language development?

4 Language Change and Evolution One problem associated with evolution but which can only be addressed indirectly or speculatively concerns the genesis of the proto-language or proto-languages in connection with the phylogenesis of the language faculty, which is, after all, difficult to conceive of as a purely abstract disposition. Pinker and Bloom [7] have examined this problem and we must leave it at that here. The question that we wish to address and answer here is as follows: Do the principles of evolution apply to language change? Or, to be more precise: Is language change, like biological evolution, the result of mutation and selection? Before beginning a serious discussion of this question, a seemingly plausible and often-made error is to be rejected, which clearly shows what language change is

112

M. Bierwisch

not. One pertinent example that is found in many different guises is the phenomenon of phonetically reducing unstressed syllables as illustrated here: we are not going to stay > we aren’t goina stay > we ain’t gonna stay it is not necessarily so > it isn’t necessarily so > it ain’t necessarily so. We must not try to explain such reduction and assimilation of segments as a type of mechanical attrition, as seen on worn out tires or well-trodden stairways, but rather as a change to the internal sound form, i.e. as license within the internal language. A phonetic effect has to be grounded in the internal language in order to become a repeatable phenomenon of the external language and manifest itself as an effect of language-change. Although the notion of language decay has since the romantic era suggested otherwise, phonetic reduction (along with its opposite, phonetic expansion) is not a mechanical process but rather a mental one. This applies all the more to grammatical changes or changes in meaning, such as the reduction of case distinctions or the shifting of semantic boundaries. All serious attempts to analyze and explain language change give consideration to this insight. The qualifying studies that fulfill this prerequisite draw upon a rich repertoire of carefully documented and analyzed phenomena found in numerous and diverse languages and dialects, including the classic facts derived from the Indo-European languages mentioned in Sect. 1 above. We must distinguish between two opposing schools of thought which, though occasionally approximating one another in their descriptive details, pursue strictly different explanatory approaches. We may label them functional/teleological and causal/teleonomic, but in essence they correspond to the Lamarckian and Darwinian understandings of evolution. Whereas teleology views the emergence of formal traits as a consequence of functional purposes, teleonomy sees a causal explanation, independent of function, behind the emergence of these traits, which then subsequently either demonstrate their fitness and survive, or else disappear. One thing that the teleological and teleonomic explanations for language change share in contrast to the mechanical view is the insight that language characteristics and their changes always, both in the long-term historical and narrower local perspective, represent an internal language phenomenon and are thus part of that sphere that corresponds to the genome: only that which reaches the elements and rules in the speaker’s mind can pass to the external language and find expression in speech. The crucial difference between the two types of explanation lies in the question of how linguistic elements originate. The teleological explanation states that internal language elements, distinctions, and rules develop during the formation of external language in a goal-directed manner, that is, in principle, intentional, though not necessarily involving conscious reflection. Words, forms and the rules that govern them develop for functional reasons. They are created, acquired and passed on in order to satisfy functional needs. This also applies to previously acquired or generated elements, which are deployed or modified in accordance with intended goals in full adherence to the Lamarckian concept of evolution.


113

Following the Darwinian idea, the teleonomic explanation focuses on the transmission of given structures, during which, for any number of reasons, variations may arise which are then subject to selection, in this case based on whether a variant promotes or hinders understanding within the language community. What is left is to explain the character and origin of the variants, which represent the counterparts of the genome mutations found in biological evolution. A causal parallel between biological mutations and language variants, however, can at most be seen in the fact that “copying errors” may play a role in both processes. As one of the sources for variants of the language structure in this sense we again look to language acquisition, where copying errors can play a systematic role, for example by simplifying, with the aid of the language faculty, input information during processing. In any case, the critical point is that the root cause of language variants necessarily lies in the phenotype sphere, i.e. in the external language, while that of biological mutations is found in the genome, which is not subject to the causality of the phenotype. With respect to language, the emergence and selective survival of variants do not occur in separate spheres characterized by different elements and principles, but are indeed both based on the same structures. For this reason we must examine, in unavoidably abridged form, the organization of the internal language, which (with the above reservation) is analogous to the genetic information in living organisms. The two primary aspects of language faculty underlying every possible internal language enable firstly the creation of complex symbol inventories and secondly the combination of these symbols based on recursive rules and principles. Although these two aspects are inseparably meshed, they are associated with very different types of potential variants, an adequate elaboration or demonstration of which would stretch beyond the scope of this paper. A relatively easier task is to examine these two complex phenomena: 1. Lexical units derive from a reservoir of possibilities for differentiating signals, concepts and combination types. 2. Syntactic principles enable processing strategies, the availability of which is what essentially constitutes the faculty of language. In very crude approximation, these phenomena correspond to (1) the conditions of the lexical system, and (2) the organization of grammar. The resulting possibilities and options circumscribe a terrain that has been intensively explored in the cognitive sciences, most particularly by linguists. Notwithstanding the many unresolved questions, the research does license the conclusion that some structured leeway is guaranteed in the internal language for variations generated due to different causes. This applies not only to lexical units (both random and functionally motivated variants for naming conceptual complexes), but more importantly to the morphosyntactic conditions and patterns to which the combinatorics are subject. But there are still two crucial and related differences compared to variant formation as seen in biological evolution. The first difference arises from the fact that the internal language is an expression derived from and bounded by the language faculty, which for its part is a product of evolution, but which above all functions as a variation framework for

114

M. Bierwisch

which there is no apparent counterpart in the mechanism of phylogenesis. The faculty of language thus forms a set of conditions which, from a strictly formal perspective, represents the counterpart to the totality of biophysical conditions from which emerge the structures of potential variants in the genome. This means that variant formation in the realm of the internal language is bounded and determined within a specific domain and in a particular manner, which itself originated as a result of evolution. The second, very closely related difference is decisive here since it violates, as it were, a central tenet of the Darwinian theory of evolution, namely that variation and selection belong to different spheres of causality. The variants that can potentially emerge within the limits of phenomena (1) and (2) – such as the differentiation or reduction of case forms or other morphological categories, changes to lexical units, the modification of syntactic word order conditions or changes to phonetic characteristics as witnessed in the sound shift – all variants of this type belong to the same sphere of differentiation and selection in which the external language also resides. With respect to language change, the genotype and phenotype are thus not caged within separate spheres of causality, even if the conditions underlying the selection of relevant traits need not at all coincide with the intentional function of external language. In other words, the communicative intent is by no means identical to the chosen means of linguistic communication. So we are apparently left with a stalemate between the teleological and teleonomic arguments. Not only is it difficult in specific cases to distinguish between function-based variant formation on the one hand and variant selection based on the fitness of cause-induced variants on the other, the very basis for making such a distinction also appears to be nonexistent, since in principle the same conditions apply to both functionally motivated variation and to selection. But this impression is incorrect, as is evidenced by the wide variety of structural phenomena in language that can only be explained teleonomically (based on the conditions of the language faculty), but by no means teleologically (directed by purpose). One of many examples backing this conclusion is a typical phenomenon found in the syntax of various Germanic languages in which the verb must be placed at the end of the sentence under certain conditions but towards the front under other conditions. In German, we find cases such as the following sentences (a) and (b): (a) . . . weil sie den Kurs rechtzeitig beendeten (. . . because they finished the course in time); (b) . . . denn sie beendeten den Kurs rechtzeitig (. . . since they finished the course in time). Replacing the verb beenden in these examples with the synonym einstellen reveals a further particularity of German syntax: In words that combine a verb and a prefix, such as einstellen, aufh€ oren, anlegen, abtreten and countless others, only the verb constituent is subject to the described word order variation, despite the fact that the intended meaning is only produced through the combination of verb and prefix:


115

(a’) . . . weil sie den Kurs rechtzeitig einstellten (. . . because they terminated the course in time); (b’) . . . denn sie stellten den Kurs rechtzeitig ein (. . . since they terminated the course in time). The difference between (a) and (b) cannot be explained teleologically, and the structure in (b’) would even have to be described as almost malfunctional: The word einstellen (terminate, close down) is split in the sentence in a way that has absolutely nothing to do with its meaning. This phenomenon and others like it are not marginal or secondary. They can be explained teleonomically and systematically as deriving from the principles of the language faculty, assuming that the relevant criteria are accordingly defined within the variation limits allowed by the language faculty. Although the details behind this explanation cannot be presented here, a number of comprehensive analyses on this topic have been published by linguistics researchers in recent decades, discussed a. o. in Haider’s Deutsche Syntax [4]. The key finding here is that the organization of the language faculty provides not only for the principles required for language structuring but also for leeway or license in permitting variation. This situation thus allows both for characteristics that better fulfill particular functions and are hence selected as well as for characteristics that are teleologically unmotivated but which satisfy the principles of the language faculty. Haider [5] summarized the crux of the matter in his conclusion that not every why has a wherefore. This, however, also implies that in context of language change the genotype and phenotype, in contrast to biological evolution, do not reside in separate domains and that properties can indeed also emerge and be passed on teleologically. It must be noted that there is an important difference as to just how this works with respect to the phenomena indicated in (1) and (2) above (or, more simply, for lexicon and grammar). The majority of lexical units and changes associated with the lexical system are motivated more or less directly by function. The whys and wherefores of their existence merge here, something that is not seen, for example, in the syntax of verb placement. Certain interferences, however, make it difficult to draw a clear line between the two phenomena. German’s borrowing of verbs such as updaten or downloaden can on the one hand be explained as serving specific functional needs associated with computer technology, but such loans can on the other hand lead to violations of the German rules of morphology and verb placement. Unless we are willing to generously and vaguely equate evolution with change, an interesting and by no means trivial situation arises within the study of language development. On the one side, the processes of language change and those of biological evolution are principally different due to the fact that language change has no analogue to biological evolution’s categorical distinction between genotype and phenotype and hence to the separation of variation and selection associated with this distinction. On the other, variation and function in the field of language change are also subject to different conditions that are not reducible to one another, so that the essential logic behind variation and selection also applies to the features of the language structure. In the interplay between internal and external language,

116

M. Bierwisch

this logic doubtlessly corresponds to the relationship between genotype and phenotype. For certain types of phenomena, however, the teleological explanation is pertinent either alongside of or in place of the teleonomic argument. In particular, terminology can be established by agreement or decision, and such terminology can subsequently exert an influence on other contexts by virtue of existing principles. Unlike in biological evolution, such hybrid conditions are possible here precisely because the two spheres of influence – the teleonomic and the teleological – are not mutually exclusive. Viewed in their entirety, these parallels and differences reveal that language development is an independent field in which evolutionary and functional factors work side by side with the capacity for mutual influence and interaction.

5 Epilogue: Social Change and Evolution If human language history can indeed be logically explained by an evolutionary theory whose principles are nonetheless essentially different from those that govern the development of biological species (due to the lack of separate genotype/ phenotype causality), then we are faced with the interesting and pressing question as to whether we have thus identified a principle of evolution that is universally applicable to the historical development of sociocultural structures. Seemingly favoring this supposition is the fundamental role assigned to language as a social institution and as a basis and ingredient of veritably every sociocultural institution, as Searle [9] has recently and distinctly reemphasized. The symbolic character of natural languages, which first enabled the capacity for unlimited expression, ties language symbols to agreed convention and hence inevitably to the population that supports such convention. If, therefore, the manner in which languages form, divide and transform must be viewed as a special mode of evolution, it stands to reason that this mode would describe the overall pattern of shift and change in sociocultural institutions and their underlying knowledge systems. That there are nonetheless grounds for reservation here stems from two considerations. The first concerns what is known as the domain-specificity of the language faculty. The fact that natural languages are combinatorial systems of symbols does indeed make them whole and complete in the sense that they can express any cognitive content, i.e. all that is propositional. And yet they are built upon combinatorial and representational systems that reveal characteristic possibilities and limits. The principles of the language faculty are essentially determined by the conditions required for efficiently processing complex symbol structures. It is by no means obvious that the type of teleonomic evolution associated with these phylogenetically generated preconditions can be generalized to apply to other areas.


117

The second consideration relates to the intentionality of social behavior, including the creativity of language use. For the concept of evolution to apply to language development there must first exist the conditions of randomness from which variants arise, conditions that would form the sphere of non-intentionality where potential selection can take place. But such randomness directly contradicts the goal directedness usually associated with social behavior. What we absolutely may not presuppose is the premise that actions generally rest upon a disposition that corresponds to the specificity of the language faculty, i.e. that they have a biological foundation in a domain-specific and yet universal faculty of action. The faculty of language is the prerequisite of human history, but it does not determine its course.

References 1. Chomsky N (1986) Knowledge of language: its nature, origin, and use. Praeger, New York 2. de Saussure F (1916) Cours de Linguistique Geńe´rale. Payot, Paris, Lausanne 3. Grimm J (1822) Deutsche Grammatik, Teil 1 Dieterichsche Buchhandlung, G€ottingen 4. Haider H (1993) Deutsche Syntax – generativ. Narr, T€ ubingen 5. Haider H (2001) Not every why has a wherefore. In: Bisang W (ed) Aspects of typology and universals. Akdademie-Verlag, Berlin, pp 37–52 € 6. Humboldt W von (1830) Uber die Verschiedneheit des menschlichen Sprachbaus und ihren Einfluss auf die geistige Entwicklung des Menschengeschlechtes, Gesammelte Schriften, Band VII. Akademie-Ausgabe, Preußische Akademie der Wissenschaften, Berlin 7. Pinker S, Bloom P (1990) Natural language and natural selection. Behav Brain Sci 13:707–784 8. Schleicher A (1863) Die Darwinsche Theorie und die Sprachwissenschaft. Hermann B€ohlau, Weimar 9. Searle JR (2007) What is language: some preliminary remarks. In: Tsohatzidis SL (ed) John Searle’s philosophy of language. Cambridge University Press, Cambridge, pp 15–45

.

Theory of Evolution and Genetics Alberto Piazza

Abstract The main purpose of this contribution is to document the role of natural selection, a major factor in Darwinian evolution which is difficult to dissect specially in the case of human evolution. Recent major steps in human genetics can be summarized as follows: (a) the complete sequence of the human genome; (b) the Single Nucleotide Polymorphisms (SNP) discovery and characterization; (c) the HapMap Project; (d) the Human Genome Diversity Project (HGDP)-CEPH set-up of 1,000 world-wide cell lines publicly available; (e) the 1,000 genomes project; (f) The very recent draft DNA sequence of the Neanderthal Genome. An interesting advance from HGDP-CEPH genome-wide analyses on genetic diversity and population structure at the world-wide level (high resolution from technological advance allowing to type more than 500,000 SNP per individual) has been to resolve migration from adaptation and natural selection. The tests of selection used were: (a) iHS – detection of partial sweeps in the genome scenario from haplotype patterns; and, more traditionally, (b) Fst – differentiation of gene frequencies, calculated either globally or between broad geographic regions. Interestingly enough, the color of the skin problem originally pointed out by Charles Darwin in The Descent of Man, and Selection in Relation to Sex. p. 381, 1981 facsimile edition by Princeton University Press, has been elucidated by finding some related traits (SLC24A5, KITLG, MC1R) whose world geographic distribution shows how natural selection and geographic barriers are interacting. What makes us humans? The draft sequence of the Neanderthal genome (Green et al. 2010) surprisingly shows that the Neanderthal DNA signal can be found not only in the genomes of Europeans, but also in people from East Asia and Papua New Guinea, where Neanderthals never lived. Even more of interest, a catalogue of features unique to the human genome has been pointed out. Five genes affected by two substitutions

A. Piazza (*) Department of Genetics, Biology and Biochemistry, University of Turin and Human Genetics Foundation (HuGeF), Turin, Italy e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_8, # Springer-Verlag Italia 2012

119

120

A. Piazza

that either change aminoacids or introduce a stop codon, and that have become fixed among humans since the divergence from Neanderthals have been identified. The start codon in the gene TRPM1 that is present in Neanderthals and chimpanzees has been lost in some present-day humans. The TRPM1 encode melastatin, an ion channel important for maintaining melanocyte pigmentation in the skin. It is intriguing that skin-expressed genes comprise three out of six genes that either carry multiple fixed substitutions changing amino acids or in which a start or stop codon has been lost or gained. This suggests that selection on skin morphology and physiology may have played an important role on the hominin lineage. The finding of 20 top candidate selective sweep regions adds further evidence on how the present technological advances are instrumental for resolving cases of natural selection in humans too elusive to be found by traditional genetic tools: the case of skull structure (cleidocranial dysplasia and RUNX2 gene) is mentioned. Eventually a challenging topic worth of further analyses, the sexual selection in humans, has been quoted from Charles Darwin in The Descent of Man, and Selection in Relation to Sex, pp. 605–606: in fact, his prophetical thinking has not been yet fully explored: “We cannot positively say that this character, but not that, has been thus modified; it has, however, been shown that the races of man differ from each other and from their nearest allies, in certain characters which are of no service to them in their daily habits of life, and which it is extremely probable would have been modified through sexual selection”.

1 Introduction The main purpose of this contribution is to document the role of natural selection, a major factor in Darwinian evolution which is elusive and difficult to dissect, especially when the case of human evolution is dealt with. In August 1858, Charles Robert Darwin and Alfred Russel Wallace presented to the Linnaean Society of London [5] their independent discovery of the theory of natural selection and, in doing so, they radically altered our understanding of life on Earth. Darwin’s meticulously detailed book, On the Origin of Species by Means of Natural Selection, or the Preservation of Favored Races in the Struggle for Life, published 1 year later [2], provided a more comprehensive account of his evidence for natural selection and its role in producing evolutionary change. The immediate and enduring interest in Darwin’s and Wallace’s work is not only because of the powerful, unifying, and explanatory theory it provides for biology (and in prospect for medicine) but also because of its impact on us as humans and on our place in the natural world. The Origin’s final paragraph is notable for Darwin’s insight into what the volume accomplishes in natural science and his awareness regarding its impact on its future. Even more remarkable are his predictions on how his theory would stimulate a search for the causes of variation, presaging the future connection of genetics and evolutionary theory. The famous passage:

Theory of Evolution and Genetics

121

It is interesting to contemplate a tangled bank, clothed with many plants of many kinds, with birds singing on the bushes, with various insects flitting about, and with worms crawling through the damp earth, and to reflect that these elaborately constructed forms, so different from each other, and dependent upon each other in so complex a manner, have all been produced by laws acting around us. These laws, taken in the largest sense, being Growth with Reproduction; Inheritance which is almost implied by reproduction; Variability from the indirect and direct action of the conditions of life, and from use and disuse: a Ratio of Increase so high as to lead to a Struggle for Life, and as a consequence to Natural Selection, entailing Divergence of Character and the Extinction of less-improved forms. Thus, from the war of nature, from famine and death, the most exalted object which we are capable of conceiving, namely, the production of the higher animals, directly follows. There is grandeur in this view of life, with its several powers, having been originally breathed by the Creator into a few forms or into one; and that, whilst this planet has gone cycling on according to the fixed law of gravity, from so simple a beginning endless forms most beautiful and most wonderful have been, and are being evolved.

More than a relevant metaphor for the ecological interrelationship of living organisms which recalls the lush jungle environment of Darwin’s early field work in Brazil and the dense forests that line the banks of the Beagle Channel in Tierra del Fuego, it is a hymn to the “grandeur” of the evolutionary perspective, an awe at the complexity and beauty of the life-forms created in accordance with the operation of nature’s laws, freed from metaphysics.

2 Recent Major Steps in Human Genetics I will focus the attention (in some cases by quoting the relevant web site only) on the five major advances on the analysis of human evolution which in my opinion punctuated the field in the last 10 years.

2.1

The Complete Sequence of the Human Genome

Completed in 2003, the Human Genome Project (HGP) was a 13-year project coordinated by the U.S. Department of Energy and the National Institutes of Health. During the early years of the HGP, the Wellcome Trust (U.K.) became a major partner; additional contributions came from Japan, France, Germany, China, and others [8]. Project goals were to: • Identify all the approximately 20,000–25,000 genes in human DNA; • Determine the sequences of the three billion chemical base (nucleotide) pairs that make up human DNA; • Store this information in databases; • Improve tools for data analysis; • Transfer related technologies to the private sector; • Address the ethical, legal, and social issues (ELSI) that may arise from the project.

122

A. Piazza

Though the HGP is finished, analyses of the data will continue for many years. It is worth noting that the definition of “complete” sequence referred to the mosaics of DNA sequences taken from different individuals rather than to the DNA sequence of one individual. A landmark paper was published in 2008 [10] where the first high-resolution sequence map of human structural variation in eight individuals has been showed – a prelude to future individual genome sequencing projects.

2.2

The Single Nucleotide Polymorphisms (SNP) Discovery and Characterization: The HapMap Project

Various scientific endeavors had already started even before the completion of the first human genome reference sequence to identify unique genetic differences between individuals. 99.9% of one individual DNA sequences will be identical to that of another person. Of the 0.1% difference, over 80% will be single nucleotide polymorphisms (SNPs). A SNP is a single base substitution of one nucleotide with another, and both versions are observed in the general population at a frequency greater than 1%. Human DNA is comprised of only four chemical entities, e.g. A, G, C, T, whose specific chemical order is the alphabet of the genome. An example of a SNP is individual “A” has a sequence GAACCT while individual “B” has sequence GAGCCT, the polymorphism is an A/G. The most recognized public effort was spearheaded by The SNP Consortium [9], whose original mission was to determine and map about 300,000 evenly spaced single nucleotide polymorphisms within the human genome. Current estimates are that SNPs occur as frequently as every 100–300 bases. This implies in an entire human genome there are approximately 10–30 million potential SNPs. More than 4 million SNPs have been identified and the information has been made publicly available. Many of these SNPs have unknown associations. Compilation of public SNPs has produced a subset of SNPs defined as a non-redundant set of markers that are used for annotation of reference genome sequence and are thus referred to as reference SNPs (rsSNPs). Over 2.6 million SNPs have currently been assigned as “rsSNPs”. Recent work has suggested that about ten million SNPs that are common in human population are not inherited independently; rather, sets of adjacent SNPs are present on alleles in a block pattern, so called haplotype. Many haplotype blocks in humans have been transmitted through many generations without recombination. This means although a block may contain many SNPs, it takes a few SNPs to identify or tag each haplotype in the block. The HapMap Project has the goal to map such haplotypes along the human genome and provides a very powerful resource to mark the genome by very stable reference markers to allow comparisons between different human genomes.


2.3

123

The Human Genome Diversity Project (HGDP)

A publicly available DNA collection set up and administered by Centre d’E´tude du Polymorphisme Humain (CEPH) in Paris, France [1], allowed genome-wide analyses on genetic diversity and population structure at a world-wide level. Cell lines of 1,056 individuals from 52 populations have been tested at high resolution from technological advance: 500,000 SNPs per individual have been typed in an effort to resolve the effect by migration from that by adaptation and natural selection in modeling human biological variation [11]. A very simplified summary of the most recent analyses shows that the genome of each of us differs from the genome of another individual in about three million nucleotides and that about 95% of this variation has no effect on genetic characters (phenotypes) but it is influenced by demographic factors and provides very powerful information to infer the origin and the migrations of our species. The remaining 5% of human genetic variation seems to affect phenotypes: how to dissect its possible adaptive role in humans due to natural selection, it will be shortly explored in the next paragraph.

2.4

The 1,000 Genomes Project

The best way to describe this Project is to quote the abstract of the first publication by the Consortium The 1,000 Genomes Project [15], an international collaboration whose goal is to produce an extensive public catalogue of human genetic variation: The 1000 Genomes Project aims to provide a deep characterization of human genome sequence variation as a foundation for investigating the relationship between genotype and phenotype. Here we present results of the pilot phase of the project, designed to develop and compare different strategies for genome-wide sequencing with high-throughput platforms. We undertook three projects: low-coverage whole-genome sequencing of 179 individuals from four populations; high-coverage sequencing of two mother–father–child trios; and exon-targeted sequencing of 697 individuals from seven populations. We describe the location, allele frequency and local haplotype structure of approximately 15 million single nucleotide polymorphisms, 1 million short insertions and deletions, and 20,000 structural variants, most of which were previously undescribed. We show that, because we have catalogued the vast majority of common variation, over 95% of the currently accessible variants found in any individual are present in this data set. On average, each person is found to carry approximately 250 to 300 loss-of-function variants in annotated genes and 50 to 100 variants previously implicated in inherited disorders. We demonstrate how these results can be used to inform association and functional studies. We directly estimate the rate of de novo germline base substitution mutations to be approximately 10 8 per base pair per generation. We explore the data with regard to signatures of natural selection, and identify a marked reduction of genetic variation in the neighborhood of genes, due to selection at linked sites. These methods and public data will support the next phase of human genetic research. [16]

124

2.5

A. Piazza

The Draft DNA Sequence of the Neanderthal Genome

A very recent finding (May 2010) which will be explored below.

3 Natural Selection and Population Differentiation Genetic DNA variants conferring an advantage to better adaptation will be selected by nature: this process is one ingredient of evolution which distributes genetic variation in space (population differentiation) and in time as the environment changes with time. Well known examples are some red-blood-cell disorders (e.g. sickle cell anemia and thalassemia) which are caused by a pathological DNA mutation inherited from both parents. The remarkable point is that if this DNA mutation is inherited from one parent alone not only the disorder is absent, but the individual who carries it is less susceptible to malaria infection. This better adaptation was strong and detectable still today for malaria, but it is much more elusive for other traits. Identifying targets of positive selection in humans has, until recently, been frustratingly slow, relying on the analysis of individual candidate genes. Genomics, however, has provided the necessary resources to systematically interrogate the entire genome for signatures of natural selection. To date, more than 20 genome-wide scans for recent or ongoing positive selection have been performed in humans. A key challenge is to begin synthesizing these newly constructed maps of positive selection into a coherent narrative of human evolutionary history and derive a deeper mechanistic understanding of how natural populations evolve [13]. Three questions have been generally addressed: • To which extent has natural selection influenced, at the scale of the entire genome, the degree of population differentiation in modern humans? • Which type of genetic variants have been preferentially targeted by selection? • Genes and gene variants under strong selective pressures can highlight regions of the genome explaining the current population phenotypic variation? One of the parameter to test the effect by natural selection is called Fst, which measures the differentiation of gene frequencies, calculated either globally at the world level or between people separated by broad geographic regions. Empirically: (a) Look more generally at the geographic patterns of SNP’s with extreme Fst; (b) Choose the top ~200 SNPs that differentiate pairs of populations on the basis of Fst; and (c) Plot the Fst distribution of the genes associated to each SNP across the Human Genome Diversity Panel populations above. Figure 1 plots the global Fst distribution of 650.000 SNPs. It is based on the assumption that selection is sufficiently strong to generate extreme spatial patterns compared with the rest of the genome. Modified from Fig. 4b of [12].


125

400

Fst Distribution (1% tall)

300

SLC45A2

Frequency 20000 30000

40000

Frequency 100 200

50000

Fst Distribution

MC1R KITLG SLC24A5

0

OCA2

0.4

10000

SLC24A4 TYR

KITLG

0.5 0.6 Global Fst

0.7

SLC24A5

SLC45A2 MC1R

0

OCA2

0.0

0.2

0.4 Global Fst

0.6

0.8

Fig. 1 Outlier approach for identifying candidate targets of selection

The genes SLC45A2, the most extreme outlier in the figure, and KITLG are thought to account for ~30% and 20%, respectively, of the difference in dark skin pigmentation between Bantu Africans and Europeans. At a lesser extent MC1R, which is found in the 1% tail of the genome-wide distribution, is involved in skin pigmentation as well. It is a very remarkable finding. Even more remarkable are the prophetic words by Darwin: The best kind of evidence that the color of the skin has been modified through sexual selection is wanting in the case of mankind; for the sexes do not differ in this respect, or only slightly and doubtfully. On the other hand we know from many facts already given that the color of the skin is regarded by the men of all races as a highly important element in their beauty; so that it is a character which would be likely to be modified through selection, as has occurred in innumerable instances with the lower animals. [4]

4 What Makes Us Humans? The Draft Sequence of the Neanderthal Genome Published two weeks before the Meeting, the DNA draft sequence of the Neanderthal genome signed a major step in the analysis of our species evolution [7]. The first proto-Neanderthal traits appeared in Europe as early as 600,000–350,000 years ago. Associated with the Chatelperronian industry, Neanderthal man shared their habitat with Homo sapiens and was found in Eastern and parts of Western Europe, and some areas of Western and Central Asia. In 2008 the

126

A. Piazza

mitochondrial DNA (the mitochondrion is a cellular membrane-enclosed organelle which generates most of the cell’s supply of chemical energy) of a Neanderthal was extracted and completely sequenced [6]. The analysis showed it differs from that of modern humans but shares a common ancestor with humans around 500,000 years ago. When compared to modern human it was inferred that Neanderthals donated little or no mitochondrial DNA to our species. The draft Neanderthal nuclear DNA sequence has still to be refined, but, despite its limitations, is in any case extremely useful because human and chimpanzee genomes are available for comparison: places where humans differ from chimps, while Neanderthals still have the ancestral chimp sequence, may represent uniquely human genetic traits. Such comparisons enabled the researchers to catalog the genetic changes that have become fixed or have risen to high frequency in modern humans during the past few hundred thousand years. To help make further informative comparisons, Green et al. [7] sequenced the genomes of five present-day individuals from different parts of the world: southern Africa, West Africa, Papua New Guinea, China, and western Europe. By quoting their words: Surprisingly the Neanderthal DNA signal shows up not only in the genomes of Europeans, but also in people from East Asia and Papua New Guinea, where Neanderthals never lived. The research found the genetic signal of Neanderthals in all the non-African genomes, meaning that the admixture occurred early on, probably in the Middle East, and is shared with all descendants of the early humans who migrated out of Africa.

The observation that the Neanderthals genome appears more closely related to the genome of Asian and European than to that of Africans is particularly striking as there is, to date, no fossil evidence that Neanderthals existed in East Asia or Papua New Guinea. Green et al. [7] suggest that between 1% and 4% of the genomes of people in Eurasia are derived from Neanderthals and therefore gene flow between Neanderthals and modern humans occurred prior to the divergence of European and Asian populations (between 70,000 and 50,000 years ago), as sketched in the Fig. 2 below.

5 A Catalogue of Features Unique to the Human Genome What kind of genes show important changes in recent human evolution? Green et al. [7] identified a catalog of 72 genetic features unique to modern humans by comparing the Neanderthals, human, and chimpanzee genomes. Genes involved in cognitive development, skull structure, energy metabolism, and skin morphology and physiology are among those highlighted in the study as likely to have undergone important changes in recent human evolution. The Authors claim to have identified five genes affected by two substitutions of DNA sequence that either change aminoacids or introduce a stop codon, and that have become fixed among humans since the divergence from Neanderthals: • DCHS1 (CCDS7771), which encodes fibroblast cadherin-1, a calcium dependent cell-cell adhesion molecule that may be involved in wound healing.


127

Fig. 2 Divergence of European and Asina populations between 70,000 and 50,000 years ago

• RPTN (CCDS41397), which encodes repetin, an epidermal matrix protein that is expressed in the epidermis and particularly strongly in eccrine sweat glands, the inner sheaths of hair roots and the filiform papilli of the tongue. • SPAG17 (CCDS899) sperm-associated antigen-17 that is thought to be important for the structural integrity of the central apparatus of the sperm axoneme, which is important for flagellar movement. • TTF1 (CCDS6948), a terminator of ribosomal gene transcription and regulator of RNA polymerase I transcription. And • SOLH (CCDS10410), which encodes a protein of unknown function. To these five genes we could add • The start codon in the gene TRPM1 that is present in Neanderthals and chimpanzees has been lost in some present-day humans. The TRPM1 encode melastatin, an ion channel important for maintaining melanocyte pigmentation in the skin. It is intriguing that skin-expressed genes comprise three out of six genes that either carry multiple fixed substitutions changing amino acids or in which a start or stop codon has been lost or gained. This suggests that selection on skin morphology and physiology may have played an important role on the hominin lineage.

128

A. Piazza

Table 1 Top 20 candidate selective sweep regions Region (hg 18) S Width (cM) chr2:43265008-43601389 6.04 0.5726 chr11:95533088-95867597 4.78 0.5538 chr10:62343313-62655667 6.1 0.5167 chr21:37580123-37789088 4.5 0.4977 chr10:83336607-83714543 6.13 0.4654 chr14:100248177-100417724 4.84 0.4533 chr3:157244328-157597592 chr11:3060100-30992792 chr2:176635412-176978762

6 0.425 5.29 0.3951 5.86 0.3481

chr11:71572763-71914957 chr7:41537742-41838097 chr10:60014775-60262822 chr6:45440283-45705503 chr1:149553200-149878507

5.28 6.62 4.66 4.74 5.69

0.3402 0.3129 0.3129 0.03112 0.3047

chr7:121763417-122282663 chr7:93597127-93823574 chr16:62369107-62675247 chr14:48931401-49095338 chr6:90762790-90903925 chr10:9650088-9786954

6.25 5.49 5.18 4.53 4.43 4.56

0.2855 0.2769 0.2628 0.2582 0.2502 0.2475

Gene(s) ZFP36L2;THADA JRKL;CCDC82;MAML2 RHOBTB1 DYRK1A NRG3 MIR337;MIR665;DLK1;RTL1; MIR493;MEG3;MIR7770 KCNAB1 HOXD11;HOXD8;EVX2;MTX2;HOXD1; HOXD10;HODX13;HOXD4;HOXD12; HOXD9;MIR10B;HOXD3 CLPB;FOLR1;PHOX2A;FOLR2;INPPL1 INHBA BICC1 RUNX2;SUPT3H SELENBP1;POGZ;MIR554;RFX5; SNX27;CGN;TUFT1;PI4KB;PSMB4 RNF148;RNF133;CADPS2

BACH2

In the following table (Table 1) a catalogue of the top 20 candidate genome regions, ordered by decreasing width in centimorgans (cM), the unit of genetic length, is shown . They require further, more detailed investigation and correlation with expression. One gene of interest among them may be RUNX2 (CBFA1) on chromosome 6 which is the only gene in the genome known to cause cleidocranial dysplasia, which is characterized by delayed closure of cranial sutures, hypoplastic or aplastic clavicles, a bell-shaped rib cage, and dental abnormalities. Some of these features affect morphological traits for which modern humans differ from Neanderthals as well as other earlier hominids. For example, the cranial malformations seen in cleidocranial dysplasia include frontal bossing, i.e. a protruding frontal bone.

6 The Sexual Selection in Humans: A Challenging Topic Worth of Further Analyses The views here advanced, on the part which sexual selection has played in the history of man, want scientific precision. He who does not admit this agency in the case of the lower animals, will disregard all that I have written in the later chapters on man. We cannot


129

positively say that this character, but not that, has been thus modified; it has, however, been shown that the races of man differ from each other and from their nearest allies, in certain characters which are of no service to them in their daily habits of life, and which it is extremely probable would have been modified through sexual selection. We have seen that with the lowest savages the people of each tribe admire their own characteristic qualities, – the shape of the head and face, the squareness of the cheek-bones, the prominence or depression of the nose, the color of the skin, the length of the hair on the head, the absence of hair on the face and body, or the presence of a great beard, and so forth. Hence these and other such points could hardly fail to be slowly and gradually exaggerated, from the more powerful and able men in each tribe, who would succeed in rearing the largest number of offspring, having selected during many generations for their wives the most strongly characterized and therefore most attractive women. For my own part I conclude that of all the causes which have led to the differences in external appearance between the races of man, and to a certain extent between man and the lower animals, sexual selection has been the most efficient. [3])

The quotation above, as many conjectures by Darwin, includes a series of work hypotheses very plausible for animals but difficult to test for humans, especially in modern times when cultural factors on sexual selection may shadow biological pressures. The technological advances in analyzing thousands of genes at the same run make it more affordable to pick them out today and appreciate once more Darwin’s revelatory vision of nature and of man in it. The full understanding of why sex is evolutionary advantageous in our species, requires still some time to wait, but if we are less ambitious and like to understand minor but biologically interesting aspects of sex appeal (see for instance the popular account by [14]) a rich literature is available to us: a further evidence, among many others, of the impact the evolutionary key has and will have for interpreting our past and challenging our future.

References 1. Cann H et al (2002) A human genome diversity cell panel. Science 296:261–262 2. Darwin CR (1859) On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life, 1st edn. John Murray, London 3. Darwin CR (1871/1874) The descent of man and selection in relation to sex, 2nd edn. John Murray, London, pp 605–606 4. Darwin CR (1981) The descent of man and selection in relation to sex. Princeton University Press, Princeton, p 381 [1871 facsimile edition] 5. Darwin CR, Wallace AR (1858) On the tendency of species to form varieties; and on the perpetuation of varieties and species by natural means of selection. Proc Linn Soc Lond Zool 3:46–50 6. Green RE, Malaspinas AS, Krause J et al (2008) Complete Neanderthal mitochondrial genome sequenced determined by high-throughput sequencing. Cell 134:416–426 7. Green RE, Krause J, Briggs AW et al (2010) The draft sequence of the Neanderthal genome. Science 328:710–722 8. Human Genome Project Information (s.d.) http://www.ornl.gov/sci/techresources/Human_Genome/ home.shtml 9. International HapMap Project (s.d.) http://snp.cshl.org/

130

A. Piazza

10. Kidd JM, Cooper GM, Donahue WF et al (2008) Mapping and sequencing of structural variation from eight human genomes. Nature 453:56–64 11. Li JZ et al (2008) Worldwide human relationships inferred from genome-wide patterns of variation. Science 319:1100–1104 12. Novembre J, Di Rienzo A (2009) Spatial pattern of variation due to natural selection in humans. Nat Rev Genet 10:745–755 13. Pickrell JK, Coop G, Novembre J et al (2009) Signals of recent positive selection in a worldwide sample of human populations. Genome Res 19:826–837 14. Roach M (2005) Roots of desire: the myth, meaning and sexual power of red hair. Bloomsbury, New York 15. The 1000 Genomes Project (s.d.) www.1000genomes.org 16. The 1000 Genomes Project, Consortium (2010) A map of human genome variation from population-scale sequencing. Nature 467:1061–1073

Genes, Evolution and the Development of the Embryo Giuseppina Barsacchi

Abstract Evolutionary Developmental Biology (Evo-Devo) deals with the relationships between the individual development and the phenotypic changes of the organism during evolution. Major morphological transitions in evolution are presently recognized to be accommodated by a few key developmental genetic changes (part of a “developmental reprogramming”) and “case studies” in snakes, ducks, bats, dolphins, insects, and finches, providing examples of developmental bases of evolutionary change, are presented. On the other hand, the molecular changes occur in an otherwise conserved developmental genetics tool-kit (e.g., the Hox genes for anterior-posterior patterning, the network for eye formation) representing the “deep homology” underlying diversity of forms. Based on a relationship between embryo development and organism evolution, Evo-Devo represents a synthesis between Developmental and Evolutionary Biology.

1 “Evo-Devo”: A New Discipline with Darwinian Roots Evolutionary Developmental Biology, usually nick-named “Evo-Devo”, explores the relationships between the processes of individual development and the phenotypic changes of the organism during evolution. Evo-Devo represents a synthesis between Developmental and Evolutionary Biology, based on a relationship between embryo development and organism evolution. In fact “developmental reprogramming” [1] may generate the phenotypic diversity – the Darwin’s “variation” – which natural selection can act upon producing evolutionary novelties.

G. Barsacchi (*) Lab. of Cell and Developmental Biology, Department of Biology, University of Pisa, Pisa, Italy e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_9, # Springer-Verlag Italia 2012

131

132

G. Barsacchi

Academically, Evo-Devo was born around year 2000, when the first dedicated Journals and Societies were established, but it is however rooted in an ancient and noble tradition, including Darwin himself. Indeed, Charles Darwin fully appreciated the relationship between embryology and evolution. In a letter to the American botanist Asa Gray (1860) [2] he praises the role of Embryology in providing evidence for the “change of forms”: “Embryology is to me by far the strongest class of facts in favor of change of forms”. In a complementary manner, in “On the origin of species” (1859) [3] Darwin recognizes that “Community of embryonic structure reveals the community of descent”. Thus, Darwin fully appreciates that embryo development can provide evidence for both conserved structures (the “community of embryonic structure”), and changes affecting those structures (“changes of forms”) in due time and circumstances. Through his own work Darwin demonstrates that similarities between embryos may reveal phylogenetic relationships, thus contributing to the newborn nineteenth century field of Evolutionary Embryology – a precursor discipline to Evo-Devo. For instance, in his huge monograph on Cirripedia Darwin easily adopts Embryology as a methodological tool to reveal homologies: by discovering that the larva of the barnacles looks like that of the shrimps (nauplius), he establishes that the barnacles are not Mollusks but Crustaceans and is able to revise the erroneous taxonomy of this group of Invertebrates [4]. In fact Darwin considered the similarities between embryos, as compared to the dissimilarities between adult forms, one of the strongest arguments in support of his theory of evolution. Another example of nineteenth century Evolutionary Embryology prompted an enthusiastic reaction from the very same Charles Darwin, who, in “The Descent of Man” declares [5]: “Some observations lately made by M. Kowalevsky will form a discovery of extraordinary interest. The discovery is that the larvae of Ascidians are related to the Vertebrata. . .” a great discovery indeed, since, based on the adult morphology, Ascidians were classified either as Mollusks devoid of a shell or as Worms. Thus, Embryology reveals the proximity of Ascidians (Tunicates) to Vertebrates “. . .in their manner of development, in the relative position of the nervous system. . .” – that is dorsal in the larvae of Ascidians as it is in Vertebrates – “and in possessing a structure closely like the chorda dorsalis of vertebrate animals”. The following is the Darwin’s conclusion: “It thus appears. . .if we may rely on embryology, which has always proved the safest guide in classification that we have at last gained a clue to the source whence the Vertebrata have derived”. Again, here Darwin pays a great tribute to Embryology, but, more importantly, he recognizes that classifying the Ascidians as Chordates may pave the way to enquire into the origin of Vertebrates: “We should thus be justified in believing that at an extremely remote period a group of animals existed, resembling in many respects the larva of our present Ascidians, which diverged into two great branches, the one retrograding in development and producing the present class of Ascidians, the other rising to the crown and summit of the animal kingdom by giving birth to the Vertebrata.”

Genes, Evolution and the Development of the Embryo

133

Fig. 1 Thomas H. Huxley and Julian Huxley (1893)

Recent genomic data have confirmed and extended the Kowalevsky’s discovery: Tunicates are not only relatives of Vertebrates, but surprisingly they – and not Cephalochordates – appear to represent the closest living relatives of Vertebrates [6]. The great Thomas H. Huxley (1825–1895; Fig. 1), a strenuous advocate of the Darwin’s theory of evolution, also elaborates on the concept of the relevance of Embryology for Evolution and in a very sharp sentence asserts [7]: “So far as individual plants and animals are concerned, therefore, evolution is not a speculation but a fact; and it takes place by epigenesis”. The last part of this statement interests us most, since “epigenesis” here means the building of a body structure through embryo development. To complement the theory of variation and natural selection, we therefore would need a theory on how a body is built through development: a theory to explain how development can generate those changes in anatomy, which selection can act on. However, a sound understanding of embryo development that could be formulated into a coherent theory was not available at the Thomas Huxley’s time and was only made possible after the impressive twentieth century achievements of classic and molecular genetics and of molecular and cell biology. In the meantime, in 1942 another Huxley (Julian, Fig. 1) had modernized his grandfather view by suggesting: “A study of the effects of genes during development is as essential for an understanding of evolution as are the study of mutation and that of selection” [8]. The present genetic program of Evo-Devo, on which this paper is focused, is complying with the Julian Huxley’s expectation.

134

G. Barsacchi

2 Genes, Development and Evolution: The Genetic Program of Evo-Devo The concepts expressed by François Jacob in the 1970s, stemming from his discoveries on gene regulatiom in Prokaryotes, have oriented our thoughts on which genes to look for in the Evo-Devo perspective: these are “regulatory genes” – genes that stand high in the hierarchy of gene activities and control the function of many other genes. For example, a class of regulatory genes codes for transcription factors, proteins capable of binding DNA and of generating “regulatory circuits” or “gene networks” that control the activity of many other genes. In 1977 Jacob wrote [9]: “The genetic program is executed through complex regulatory circuits that switch the different biochemical activities of the organism on or off. Very little is known as yet about the regulatory circuits that operate in the development of complex organisms. (. . .) It seems likely that divergence and specialization of mammals, for instance, resulted from mutations altering regulatory circuits rather than chemical structures.”

The present knowledge of the developmental regulatory circuits is enormously increased with respect to the 1970s but, as it will be shown later in this chapter (see paragraph 5) the Jacob’s general conclusion holds true. In fact, for Jacob evolution works by “tinkering” with regulatory genes: “It is always a matter of using the same elements, of adjusting them, of altering here or there, of arranging various combinations to produce new objects of increasing complexity. It is always a matter of tinkering.” [9]

Evo-Devo has demonstrated two unexpected phenomena concerning developmental regulatory genes, which represent tools for tinkering. Firstly, the accumulation of molecular and genetic data uncovered an incredible similarity of developmental regulatory genes throughout animals. In general, the conserved regulatory genes have a special function in development: they are engaged in determining the overall body plan and the number, identity, pattern of body parts [10]. They therefore constitute the “genetic tool-kit” that controls development of an animal from an egg into an adult, driving formation of specific features. In the developmental tool-kit, genes do not act individually but as networks of interacting genes, functioning in concert to deploy a given developmental function. Most tool-kit genes code for two classes of gene products with the most global effects on development: signaling pathway factors and transcription factors. The two classes of gene products are functionally connected, since the signal pathway factors link paracrine factors – acting outside the cell – to transcription factors – acting inside the cell’s nucleus (Fig. 2). The signal transduction pathways – the chains of biochemical signaling linking the cell environment to the cell nucleus – are highly conserved in different Phyla. Conservation of signaling pathway factors and transcription factors is both a result of, and a substrate for, tinkering.


135

PARACRINE FACTOR

SIGNAL TRANSDUCTION PATHWAY

TRANSCRIPTION FACTOR Gene

Nucleus

Enhancer

Fig. 2 The tool-kit genes encoding paracrine factors, signaling pathway factors and transcription factors are highly conserved in different animal Phyla (Kind gift from Prof. S.F. Gilbert. Modified from devbio8e-fig-06-13-2.jpg)

As examples, are parts of the developmental genetic tool-kit: • Genes that control formation of the body axes, such as the Hox genes for the Anterior-Posterior (A-P) axis (see paragraph 4) and the chordin/BMP4 genes for the Dorsal-Ventral (D-V) patterning; • The Otx and Emx genes, which are involved in anterior patterning and cephalization; • Pax6 that, in a network with other genes, drives eye development (see paragraph 3); • Distal-less, which controls appendage formation (see paragraph 5, Heterotypy); and many more: developmental tool-kit genes are extensively discussed in [10, 11]. Many discoveries have now confirmed the great extent of conservation of the tool-kit genes across different Phyla, despite the differences between a human and a fly eye or brain or leg.

136

G. Barsacchi

The flexibility of gene regulation is the second phenomenon allowing – and underlying – tinkering. Developmental genes are regulated by multiple DNA sequences, the enhancers, which can each control the gene activity in a different body region. Enhancers are like the different keys of a piano that can produce different melodies according to the pattern with which they are played. For example, the different enhancers of the Pax6 gene can activate Pax6 expression either in the pancreas, or in the lens and cornea, or in the neural tube, or in the retina. Thus, modularity of enhancers allows gene expression to be changed in one organ without changes affecting other organs. Modularity of enhancers is a perfect example of the effects and of the potentialities of tinkering.

3 The Concept of “Deep Homology” and the Case of Eye Evolution Based on the discovery of these two phenomena – conservation of the developmental genetic tool-kit and flexibility of gene regulation – the concept of “deep homology” has been proposed to indicate the conserved “genetic regulatory apparatuses that are used to build” specific animal features during development – and the features produced by “deeply homologous” genes can be “morphologically and phylogenetically disparate” [12]. On this view, “deep homology” is deeply buried inside the cells and not necessarily manifest in the surface of morphology. Perhaps the eye represents the most famous case that fits with the “deep homology” description: eyes are morphologically disparate and their evolutionary origin represents a conceptual platform for different views since Darwin. In “On the Origin of species” Darwin devotes a whole paragraph of Chap. 6 to the question of the possible origin of the eye by natural selection [3]. Significantly, Chap. 6 is entitled “Difficulties on Theory” and the paragraph dedicated to the eye is entitled “Organs of extreme perfection”. To some extent rhetorically, Darwin asks: “Can we believe that natural selection could produce. . . organs of such wonderful structure, as the eye, of which we hardly as yet understand the inimitable perfection?”. Darwin appears to be fully aware of the difficulties concerning eye evolution. He approaches this subject carefully and is even sympathetic with skeptics: “. . . though I have felt the difficulty far too keenly to be surprised at any degree of hesitation” but nevertheless he thinks he can recognize a graduated series of variations in the eyes of some animal groups (i.e., Crustaceans) supporting the idea that all eyes evolved by natural selection, starting from a simple ancestral eye. At variance, based on a wide morphological, structural and embryological comparison, the influential work of Salvini-Plawen and Mayr [13] proposes that eyes originated through 40–65 independent events during evolution.


3.1

137

The Genetic Network for Eye Development

Here is where the genetic program of Evo-Devo comes into play. Indeed, over the past 15 years many insights into the evolution of eyes came from descending beneath the visible diversity of animal eyes into the genetic machinery that controls their development, providing us with a textbook example of deep homology [12, 14]. Homologous transcription factor genes are co-expressed in the embryo territories (eye fields) fated to generate the eye in both Drosophila and vertebrates; furthermore, the individual genes are connected in similar genetic networks in both invertebrates and vertebrates, even though these networks specify formation of eyes as different as the compound eye of insects and the camera eye of vertebrates [15, 16] (Fig. 3). The networks include transcription factors encoded by members the eyeless, sine oculis and eyes absent gene families in Drosophila and their homologous in vertebrates.

+ Tll, Optx2 (late)

toy ey so

eya dac

Fig. 3 The genetic network for eye specification is conserved between invertebrates and vertebrates. Top schemes: the expression domains of the transcription factors specifying the eye in Drosophila (left) and Xenopus (right) are outlined in different colors. Eye specification requires co-expression of transcription factors in space and time. Middle schemes: proposed gene networks for eye specification in Drosophila (left) and Xenopus (right). Bottom left: a Drosophila compound eye (From [14], courtesy of Prof. W. Gehring, with permission from Elsevier). Bottom right: the R. Magritte “Le faux miroir” is used to symbolize the vertebrate eye. Top and middle schemes from [15, 16] for Drosophila and Xenopus, respectively

138

G. Barsacchi Jellyfish PaxB into fly

Squid Pax6 into fly

antenna antenna

wing wing

Drosophila eyeless/Pax6 into fly

Mouse Pax6 into fly

leg

leg leg

Fig. 4 The PaxB/Pax6 gene of either jellyfish, squid or mouse elicit ectopic eye formation in transgenic flies (Drosophila) (From [17, 18, 20], respectively; courtesy of Prof. J. Piatigorsky and Prof. W. Gehring; with permission from Elsevier, P.N.A.S. (Copyright 1997 National Academy of Sciences, U.S.A.) and Oxford University Press). The ectopic eye (arrowhead) generated on a Drosophila leg by the eyeless/Pax6 gene of Drosophila is also shown (From http://www.dnalc.org/ view/16772-Gallery-37-Drosophila-eyeless-mutant. Courtesy of Prof. W. Gehring)

Conservation of individual genes in the eye networks is so extreme, that the PaxB/Pax6 genes of a jellyfish [17], or a squid [18], or an ascidian [19], or a mouse [20], are each able to elicit formation of ectopic eyes in transgenic Drosophila flies – on an antenna, or on a wing or on a leg, of the fly – and all these ectopic eyes have the structure of the compound eye of Drosophila, regardless of the provenance of


139

the Pax gene (Fig. 4). Thus, formation and evolution of morphologically disparate eyes depends on homologous genetic regulatory circuits.

3.2

The Origin of Photoreceptors

The conservation of the molecular genetics underlying eye formation, contrasting with the diversity of eyes, has resuscitated the question of the evolutionary origin of eyes but at different levels: both at the level of the regulatory genetic mechanisms underlying eye development – as briefly outlined above – and at the level of individual cell types. Special attention is devoted to photoreceptors, the retinal cells capable of capturing light initiating the process of image formation. Two main types of photoreceptors, rhabdomeric and ciliary, exist in the different taxa [21, 22] (Fig. 5a). The two kinds of photoreceptors are differentially distributed among animals, with a prevalence of rhabdomeric photoreceptors used for vision in invertebrates and with the ciliary photoreceptors being the only type of photoreceptors employed for image-forming vision in the vertebrate eye. The two types of photoreceptors differ as for their structure and morphology; they also use opsins of different gene families (r-opsins or c-opsins for rhabdomeric or ciliary photoreceptors, respectively) and distinct phototransduction cascades. Their distinct cellular type and distribution has represented an argument in favour of the separate origin of the different types of eyes. It is now clear that bilaterian animals typically have both types of photoreceptor cells, but it depends on the phylum as to which type is used for vision. Ciliary photoreceptors with a vertebrate-type opsin have been discovered in an invertebrate brain: while the marine ragworm Platynereis dumerilii hosts rhabdomeric photoreceptors in its eyes, ciliary photoreceptors are present in its brain [23] and this might be a common trait in many invertebrate phyla (Fig. 5b). Based on such significant discovery, the Authors propose that early metazoans possessed a single type of precursor photoreceptor cell that used an ancestral opsin for light detection, photoperiodicity control and possibly phototaxis. In prebilaterian ancestors, duplication of the opsin gene into c-opsin and r-opsin allowed the diversification of the precursor into ciliary and rhabdomeric cell types. Accordingly, urbilaterians – the last common ancestors of bilaterians – possessed both ciliary and rhabdomeric photoreceptors. In the evolving bilaterians and similarly to the setting in Platynereis, the rhabdomeric photoreceptors associated with pigment cells to form simple eyes, while the ciliary photoreceptors formed part of the evolving brain, active in non-directional photoresponse. In the evolutionary line leading to vertebrates, both photoreceptor types were incorporated into the evolving retina: the rhabdomeric photoreceptors transformed into ganglion cells (see below), while the ciliary photoreceptors became the main visual cell types, the rods and cones. Molecular fingerprinting of the specific retinal cell types [24] supports this view. Also, the derivation of rods and cones from brain ciliary photoreceptors strengthens the view that the vertebrate retina evolved as an outfolding from the brain, as recapitulated during the development of the present day vertebrate eye [24].

140

G. Barsacchi

a

b

ciliary photoreceptor in Platynereis brain

rhabdomeric ph.

ciliary ph.

c

d

Cubomedusae

melanopsin

mouse retina

Fig. 5 (a) Schematic representation of the major morphological difference between a rhabdomeric and a ciliary photoreceptor: the apical cell membrane or the cilium membrane is expanded in either cell type, respectively (From [21]; courtesy of Dr. D. Arendt and with permission from The Royal Society). (b) Scheme of a ciliary photoreceptor as found in the Platynereis brain, based on EM images (From [23]; courtesy of Dr. D. Arendt and with permission from the A.A.A.S.). (c) The lens eyes of Tripedalia cystophora possess a retina (r) endowed with ciliary photoreceptors and expressing PaxB (in pink). l: lens. Arrowheads indicate pigment layer (Modified from [17]; courtesy of Prof. J. Piatigorsky and with permission from Elsevier). (d) Section of a mouse retina where melanopsin expressing retinal ganglion cells (M1, M2) are highlighted by immunostaining. Arrows and asterisks indicate two plexuses in the inner plexiform layer (IPL). GCL ganglion cell layer, IPL inner plexiform layer, INL inner nuclear layer, OPL outer plexiform layer, ONL outer nuclear layer (From [27]; courtesy of Authors)

Vertebrate eye components have also even been found in the jellyfish eyes [25]. The Cubomedusae (box jellyfishes, e.g. Tripedalia cystophora), tiny jellyfishes about 1 cm3 large, possess amazing camera-type eyes that host a retina endowed with ciliary photoreceptors (Fig. 5c). These photoreceptors express c-opsin; c-opsin, but not r-opsin, has been found in other cnidarian’s eyes as well [26]. The Tripedalia eyes also use melanin as a shielding pigment, the same as used in vertebrate eyes. Melanin is enclosed into the cytoplasm of the Tripedalia photoreceptors, so that the jellyfish photoreceptors appear to combine in just one cell the characteristics of a photoreceptor and of a pigmented cell, that are instead split in distinct cells in the vertebrate eyes.


141

Conversely, and significantly, the vertebrate retina appears to host the descendents of the invertebrate rhabdomeric photoreceptors disguised as retinal ganglion cells (RGCs). A subset of RGCs are intrinsically light-sensitive and mediate perception of day/night cycle: they express melanopsin, an opsin of the same family as the rhabdomeric r-opsin [27] (Fig. 5d). In addition, precursors of vertebrate RGCs express transcription factors homologous to those expressed by precursors of rhabdomeric photoreceptors in the invertebrate eye (e.g., Atonal/ Math, Bar/BarH1) [28, 29]. The Atonal/Math transcription factors are critically required for both rhabdomeric and ganglion cell formation in the Drosophila and vertebrate eye, respectively: thus, two evolutionarily diverse eye types require homologous transcription factors for retinal neuron formation [30]. The whole of evidence points to a “transmutation” of rhabdomeric photoreceptors, engulfed into the vertebrate eyes, to originate retinal ganglion cells that play a major role in image processing and in entraining the circadian clock to the ambient lighting conditions. In conclusion, the vertebrate eye represents a composite structure, combining distinct types of light sensitive cells, the rhabdomeric and ciliary photoreceptors.

3.3

Deep Homology of Eye Development and the Parallel Evolution of Animal Eyes: A Model

Since both ciliary and rhabdomeric photoreceptors are found in both invertebrates and vertebrates, it now seems possible to reconstruct the light-sensitive systems that were present in the ancestors of all animals (Urmetazoa) or of all bilateral animals (Urbilateria), but we are as yet in an early phase of this reconstruction, facing a few possible models. Based on the concept of “deep homology” and on the information presently available, a recent model [12] proposes that (Fig. 6): • The Cnidarian-Bilaterian common ancestor had photoreceptors expressing c-opsin and a Pax gene (PaxB; Fig. 6a); • After the split between the cnidarian and bilaterian lineages, in ancestral-stem bilaterians rhabdomeric photoreceptors evolved, expressing r-opsin and Pax6 (Fig. 6b); • Urbilateria, the last common ancestors of all Bilaterians, probably had two types of light-sensing organs: a prototypical eye and a brain photo-clock, with rhabdomeric and ciliary photoreceptors, respectively, as they are presently found in the ragworm Platynereis (Fig. 6c); • The photoreceptor types established in the Urbilateria were then incorporated in different ways in the parallel evolution of diverse eyes in different Phyla (Fig. 6d). Rhabdomeric photoreceptors were the foundation for the evolution of compound and camera-type eyes in arthropods and mollusks, respectively.

142

G. Barsacchi

a Cnidarian-Bilaterian ancestor

e Jellyfish camera eye (ciliary)

Animal photoreceptorcell precursor (PAXB, c-opsin) PAX6, r-opsin

b Ancestral-stem bilaterians

Rhabdomeric photoreceptor

Ciliary photoreceptor

c Prototype eye

Urbilateria

Brain photo-clock

d

Arthropod compound eye (rhabdomeric)

Squid camera eye (rhabdomeric)

Vertebrate camera eye (ciliary)

Fig. 6 Deep homology of eye development and the parallel evolution of animal eyes: a model (see text for explanations) (From [12]; courtesy of Authors and with permission from Nature Publishing Group)

Both types of photoreceptors were incorporated into the vertebrate eye, with ciliary photoreceptors carrying out photo transduction and rhabdomeric receptors being transformed into ganglion cells, functioning in image processing and circadian entrainment; • The ciliary camera-type eyes of box jellyfishes are proposed to have evolved in parallel in the cnidarian lineage (Fig. 6e). In conclusion, the developmental molecular genetics of the diverse eyes – deep homology – illustrates that similar tools have been used to build a great variety of structures long thought to have completely independent histories.


143

4 The Hox Genetic Tool-Kit Specifies Anterior–Posterior Polarity Through Animals The Hox genes specify the regional identity of the anterior-posterior (A-P) body axis in the most diverse animals. The roots of our knowledge on Hox genes lie in the observations and ideas presented by William Bateson (1861–1926) in his book on “Materials for the study of variation” [31], where he reported on hundreds of changes from the normal morphology of a species that could help in understanding how evolution worked. In fact he believed that frank observations of variations present in nature were “the common basis” for all views on evolution. Bateson dedicated special attention to those changes where a structure was transformed, or formed, as to take the appearance of another existent structure: for instance, when an insect antenna had become similar to a leg; or a frog first vertebra, the atlas, had acquired processes like those of other vertebrae; or an additional vertebra was present in a frog; or a second head had formed in a turtle. To describe such weird variations he suggested a new word: “I think that a new term is demanded. (. . .) the term Homeosis (. . .) for the essential phenomenon is not that there has merely been a change, but that something has been changed into the likeness of something else.”

Thus, the concept and the word “homeosis” were born to stay with us up to the present. Bateson predicted that: “. . . this particular kind of variation will be found to be especially important and I believe that in the future its significance and the mode of its occurrence will become an object of high interest.”

He was right: homeosis is due to mutations in homeotic/Hox genes – which from homeosis draw their name – and the study of Hox genes has been providing us with a wealth of information as to how animal form is achieved; a real gold mine for scientists [32, 33]. Hox genes are evolutionarily conserved from Cnidarians to Vertebrates and are grouped in a single cluster in the genome of most animals (Fig. 7a). Over the course of vertebrate evolution, the single ancestral cluster underwent duplications to produce four gene clusters, which together with gene loss resulted in the 39 Hox genes found in all extant mammals. Each “ideal” cluster contains protein-coding genes all transcribed in the same 50 -to-30 orientation, allowing the clusters to be considered as having a 50 and a 30 end. This unique chromosomal organization facilitates coordination of Hox-cluster expression, which is characterized by “spatial and temporal colinearity”: genes located at the 30 end of the cluster are expressed more anteriorly and earlier, whereas genes more 50 are expressed progressively more posteriorly along the A-P axis and at later stages of development [34]. Colinearity establishes a partially overlapping, staggered arrangement of the Hox genes domains of expression along the A-P axis (see also [32, 33] for variations from “ideal” clustering and colinearity).

144

G. Barsacchi

a

b Drosophila

M A M M A L S

Fig. 7 (a) Cladogram representing Hox gene chromosomal organization for representative animals. At the base is shown a cnidarian (Nematostella vectensis), which has a dispersed genomic organization of Hox genes. The left branch displays fragmented Hox clusters for both lophotrochozoan (Schistosoma mansoni) and ecdysozoan (Drosophila melanogaster, Caenorhabditis elegans) species. The right (deuterostome) branch portrays the Hox cluster of the sea urchin Strongylocentrotus purpuratus, the “prototypical” Hox cluster of Branchiostoma floridae (a cephalochordate), the dispersed genomic organization of the Hox genes of a urochordate (Oikopleura dioica), and the quadruplicated Hox clusters of a mammal (Mus musculus). At the base of the cladogram is the likely Hox cluster organization of the last common ancestor of bilaterians (Urbilateria) (From [32]; courtesy of Prof. W. McGinnis, with permission from A.A.A.S.). (b) Depiction of the Hox gene (arrows) complexes of Drosophila and mammals. Loci encoding microRNA are also indicated (red arrowheads). microRNA genes are conserved between Drosophila and mammals and inhibit translation of more anterior Hox mRNA (red lines) (From [34]; courtesy of Prof. E.M. De Robertis and with permission from Elsevier)


145

From Cnidarians to Vertebrates the Hox genes shape the A-P axis of the body by specifying, during embryo development, identity and order of structures in the most diverse animals, either flies or mice or humans: where to build the head, where the tail, and where the structures in between. Hox genes accomplish such a sophisticated job by undergoing a complex spatial-temporal pattern of expression during development. It is emerging that microRNAs are major players in the complex molecular machinery of Hox gene regulation. These short cellular RNA sequences – about 20 nucleotides long – can specifically bind messenger RNA (mRNA) molecules, inhibiting their translation into a protein. It has been found that some microRNAs can bind specific Hox mRNA molecules blocking their translation in specific body regions [32, 34, 35]. In the Evo-Devo context it is of importance that this lately discovered microRNA-based mechanism appears to be conserved between invertebrates and vertebrates. Strikingly, in both Drosophila and Vertebrates the Hox genomic clusters encapsulate conserved sites encoding microRNAs, which are transcribed by the same promoters of “posterior” Hox genes and repress the activity of more “anterior” Hox genes in the cluster, in posterior body regions (Fig. 7b). Thus, regulation by microRNA of the Hox genes way of functioning appears to provide a molecular explanation for the enigmatic phenomenon of the “posterior prevalence” discovered by E.B. Lewis on a purely classical genetics ground. In accordance with the variations discovered by Bateson, when mutations affect the complex regulation of Hox gene expression, regions along the A-P axis of the body are transformed to the likeness of other regions [10, 11]. Famous examples include an improbable dipterous endowed with two pairs of wings, due to the transformation of the halters into an extra-pair of wings (bithorax); and a fly carrying a pair of legs on its head, where they replace the antennae (antennapedia). Mutations in Vertebrates include the appearance of an extra-thoracic vertebra in mouse, or of an extra-digit in man. Thus, homeotic mutations transform regions along the A-P axis into one another in the most diverse animals.

4.1

Hox Genes and the Possible Origin of the Snake Vertebral Column

Homeotic mutations provide us not only with special phenotypes, but also with hints as to how changes in Hox genes may have generated variations along the A-P axis during evolution. How, for instance, may the elongated and limbless body of a snake have diverged from the tetrapod lineage? By observing the vertebral column in diverse animals (Fig. 8), we notice that 100% of vertebrae have a thoracic identity in the snake and, as such, they carry ribs; the python has virtually no cervical vertebrae and therefore lacks a neck [36]. Furthermore, the distinct types of vertebrae – cervical, thoracic, lumbar etc. – are in different numbers in different species: the cervical vertebrae are 14 in the chick,

146

G. Barsacchi

a

thoracic

cervical 7

lumbar

sacral

caudal

Hoxc5 14

Hoxc5 17

Hoxc5

1

b

Fig. 8 Differences in the vertebral patterning correlate with shifts in Hox gene expression domains. (a) The anterior boundaries of expression of several Hox genes are shown beneath somites (circles) and vertebrae (squares). The different identity of vertebrae is matched by the different colors, as indicated on top of figure. In mammals and birds the anterior boundary of the Hoxc6 expression lies at the cervical-thoracic transition, where the forelimb buds can form. At variance, in the python both Hoxc6 and Hoxc8 have a more anterior expression boundary, reflecting the expanded thoracic vertebral identity and no forelimbs develop (see b) (From [10]; courtesy of Prof. S. Carrol and with permission from Wiley-Blackwell). (b) Lateral view of a complete skeleton preparation of python embryo at 24 days of incubation. Arrow indicates position of hindlimb rudiments (removed). The vertebrae anterior to arrow are homogeneous (From [36]; with permission of Nature Publishing Group)

17 in the goose and 7 in virtually all mammals. As a consequence, the transitions from one vertebral type to another occur at different levels with respect to the head in the different animals. The diverse vertebral anatomical patterns correlate with the expression patterns of Hox genes observed in the presumptive axial skeleton of the embryos. As examples (Fig. 8a), the Hoxc5 gene is expressed in the presumptive cervical vertebrae, while expression of Hoxc6 and Hoxc8 is confined to the trunk region; furthermore, the boundary between Hoxc5 and Hoxc6 expression precisely coincides with the boundary between the cervical and the thoracic vertebrae – regardless the actual numbers of the two kinds of vertebrae. To complement the descriptive information, coherent functional data demonstrate that the different patterns of Hox developmental expression specify the different vertebral compositions observed in the adult animals.


147

The inference from the developmental data is that shifting back or forwards the boundaries of the Hox expression domains (Hoxc5 and Hoxc6/Hoxc8 for the cervical and thoracic vertebrae, respectively) during evolution, may have determined the different distribution of the vertebral types we now observe in living or fossil vertebrates. In turn, developmental molecular data also suggest that changes in the molecular machinery regulating Hox gene function in the course of evolution, namely chromatin-remodeling proteins, cis-regulatory sequences, activity of transposable elements and microRNA sequences, could have caused the observed shifts in Hox domains of expression along the A-P axis [32–38]. The python represents an extreme example of the consequences of shifting the Hox genes expression domains along the A-P axis (Fig. 8b). In the python embryo, expansion of Hoxc6 and Hoxc8 domains along the A-P axis correlates with expansion of vertebral thoracic identity [36]. While expression of HOXC6 and HOXC8 proteins is confined to a defined trunk region in the chick embryo, it is expanded from the head to the tail in the python embryo. Thus, the loss of the snake’s neck and the expansion of its rib-bearing vertebrae correlate with the shift in expression of HOXC6 and HOXC8. From these and other studies the present model proposes that snakes progressively lost their axial regionalization, and concomitantly their limbs during evolution, due to an expansion of the domains of expression of the Hox genes specifying vertebral thoracic identity [36, 37, 39]. Recent analyses of several Hox genes expression in snake and caecilian embryos (caecilian amphibians convergently evolved a deregionalized body plan) suggest that the evolution of a snake-like body plan involved not only changes in Hox gene cis-regulation, but also a different downstream interpretation of the Hox code [40]. In conclusion, the snake case shows that a change in the place of expression of regulatory genes – “heterotopy”, see below – can generate evolutionary novelties.

5 Four Genetic Mechanisms of Tinkering Wallace Arthur [1] has proposed that changes affecting developmental regulatory genes in a “developmental reprogramming” during evolution may be of four types and has defined their respective evolutionary significance. These changes need not to be mutually exclusive but more than one change may occur at a time or at subsequent times during succeeding developmental steps. They appear to accomplish the Jacob’s idea of “tinkering”. Heterotopy, or changes in place: a developmental event is evolutionarily shifted from one part of the organism to another. Changes in the regional expression of a gene during development may produce evolutionary novelties. Heterotopy is thought to have been at work to shape the snake’s body. A novel place of gene expression is also involved in the formation of the webbed feet in some birds, such as the duck: a significant change, allowing birds to effectively exploit aquatic niches [41]. In the early embryo, the interdigital membrane is formed in the hind limb bud of either the chick or the duck (Fig. 9a).

148

G. Barsacchi

a

Newborn

Apoptosis

BMP

Gremlin

a

b

c

d

a’

b’

c’

d’

Chick hindlimb

Duck hindlimb

b untreated

gremlin

Fig. 9 A novel expression of gremlin preserves the interdigital membrane in the hindlimb of the duck. (a) b, b’ Apoptosis destroys the interdigital membrane of the developing hindlimb in the chick (b) but not in the duck (b’). In (b), areas of interdigital cell death are marked by vital staining with neutral red (arrows). c, c’ BMP4 is expressed (blue color) in the interdigital membrane of the developing feet in both chick and duck. d, d’ Expression of gremlin in the interdigital membrane of the duck (d’, arrows) but not of the chick (d), contrasts the BMP4 signaling in the duck hindlimb interdigital membrane. (b, b’, d, d’: from [41], courtesy of Dr. J.M. Hurle and adapted with permission from Development; c,c’: from [42], adapted with permission from A.A.A.S.; the setting is a kind gift of Prof. S.F. Gilbert). (b) Scanning micrographs showing the result of an experimental manipulation of chick developing hindlimb untreated (saline bead) or treated with gremlin-containing beads in interdigital space. Interdigital cell death is inhibited following gremlin treatment, producing a duck-like syndactyly in a chick limb (From [41], adapted with permission from Development)


149

However, later in development the interdigital membrane is eliminated by apoptosis (or programmed cell death) in the chick (b), but not in the duck (b’). Apoptosis is brought about by the action of secreted proteins of the BMP family, that are expressed in both chick’s and duck’s interdigital membrane (c,c’); however, in the duck BMP proteins are antagonized by expression of another secreted protein, called gremlin (d’), thus preventing apoptosis to occur. At variance, gremlin is not expressed in the interdigital membrane of the chick’s foot (d), where therefore apoptosis can take place, separating the digits one another. Thus, the novel developmental expression of gremlin in the interdigital membrane of the duck hind limb bud allows formation of the bird webbed feet and this interpretation is supported by functional experiments (Fig. 9b). In fact, the forced expression of gremlin in the interdigital space of the developing chick hind limb generates a webbed foot, mimicking the foot of a duck! The inference from this “case study” is that a spatial change in gene expression during development – namely, the novel expression of gremlin in the interdigital membrane of the hind limb bud – may have contributed to the evolution of the webbed feet in birds. A similar developmental mechanism operates to produce the chiropatagium that beautifies the bats forelimbs, rendering bats the only mammals endowed with powered flight [43]. Modifications of the bat forelimbs include elongation of the forearm and digits, reduction in bone thickness, and the presence of tissue between the digits. Maintenance of the interdigital membrane in the forelimb is due to expression of gremlin in the interdigital membrane of the bat’s embryo forelimb, but not in its hind limb nor in the mouse limbs [44] (Fig. 10). By inhibiting the BMP pathway, gremlin contributes to protect the forelimb interdigital webbing from apoptosis. Conversely, the BMP signaling plays a role in supporting the disproportionate elongation of those digits (III–V) that sustain the chiropatagium (see below, Heterometry). Recent studies implicate the Prx1 homeobox transcription factor in supporting the elongation of the bat’s forearm bones [45]. Interestingly, a cis-regulatory sequence of Prx1 – a highly conserved enhancer – accounts for at least part of the elongation of the long bones in the wings of bats. The bat’s enhancer up-regulates Prx1 transcription more distally in the cartilage and pericondrium of the forelimb, compared to the activity of the homologous enhancer in mouse. Strikingly, the bat’s enhancer is able to impart a bat’s pattern of Prx1 trancription to transgenic mice, resulting in elongation of the mouse forearm. This exciting result shows that differences in Prx1 cis-regulatory sequences in the bat compared with the mouse affect bone length. While functional tests of changes in regulatory sequences have largely been restricted to insects, this study has brought this level of Evo-Devo analysis to vertebrate systems [46]. In the same Chap. 6 of “On the origin of species” [2] entitled “Difficulties on Theory” where Charles Darwin discusses the difficulties posed by the eye (see paragraph 3), he also faces the case of evolution of bats in a paragraph entitled “On the origin and transitions of organic beings with peculiar habits and structure”. He asks: “. . .is it possible that an animal having, for instance, the structure and habits of

150

a

G. Barsacchi

b

FGF8 Gremlin BMP

BMP2

Fig. 10 Differential expression of diffusible factors (indicated on the bat’s wing) is involved in producing the differential forelimb morphology in mice and bats. (a) An adult mouse, Mus musculus. (b) An adult bat, Carollia perspicillata. Digits are numbered from anterior (I) to posterior (V). Bat digits are elongated compared with mouse digits (inset) and maintain webbing between the posterior digits. Expression of gremlin in the developing interdigital membrane prevents apoptosis by inhibiting BMP signaling in the bat forelimb. FGF8 also cooperates to maintain the bat interdigital membrane. At variance, expression of a higher amount of BMP2 correlates with the extraordinary elongation of the bat fingers that sustain the chiropatagium (see text) (Modified from [44]; courtesy of Dr. S.D. Weatherbee and with permission from P.N.A.S. Copyright 2006 National Academy of Sciences, U.S.A.)

a bat, could have been formed by the modification of some animal with wholly different habits?”. Indeed, in absence of transitional forms, it is difficult to imagine how such perfected structures as the vertebrate eye or the bat wing could arise de novo. Darwin provides indirect evidence of “instances of transitional habits and structures in closely allied species of the same genus”, referring to the evolution of flying squirrels and lemurs. The ancestors of modern bats that first appear in the fossil record about 50 My ago already have elongated digits, extensive interdigital membranes, and robust forelimb muscles indicative of powered flight. However, the common ancestor of modern bats likely originated about 64 My ago, indicating a gap of about 14 My where possible intermediate forms from quadrupedal to flying mammals could be searched [43]. In any instance, while it is still unclear whether modern bats arose gradually or rapidly from their quadruped ancestor, Evo-Devo began to elucidate some of the molecular changes required to modify the morphology of a limb into that of a wing, providing a potential explanation as to how bats were able to achieve powered flight and colonize the air. The general picture emerging from these studies is that small changes in the spatial expression of key developmental genes may have driven evolution of morphological innovations such as the bat wing. Heterochrony: change in timing. The rates of development of part(s) of an organism are evolutionarily shifted relative to each other. A change in the timing of gene expression during development may also underlie the appearance of novel structures in evolution.


a

c

151

b

AER

d AER

Fig. 11 In the dolphin embryo, the genes for some digit production are active far longer than in other mammals causing more skeletal nodules to form in the fingers, as it is shown in the cetacean example in (a). (b) Schematic reconstruction of the distribution of thickened apical ectodermal ridge (AER, in red) at developmental stages 5, 6, and late 6, respectively, in the dolphin Stenella attenuata. (c) Digit II phalanges (braces) and distal condensed mesenchyme (arrow) at stage 6. (d) Boxed area from (c). Asterisk marks thickened apical ectoderm ridge in cross-section; this ridge is also present in adjacent sections spanning digit II (From [49]; courtesy of Prof. M.K. Richardson and with permission from John Wiley and Sons)

Perhaps the most dramatic evolutionary reorganization of the autopod has occurred in cetaceans (whales, dolphins, and porpoises), whose common ancestor diverged from an extinct group of deer-like artiodactyls approximately 50 My ago [47]. Changes in limb morphology associated with the return to water include considerable variation in the number of phalanges, with digits II–IV characterized by as many as 13 in digit II of some species (Fig. 11a). Hyperphalangy appears to have evolved three times among extant cetaceans, with two reversals. According to an extensive analysis among terrestrial and secondarily aquatic extant and fossil taxa (cetaceans, ichthyosaurs, plesiosaurs and mosasaurs), extreme hyperphalangy, defined as exceeding a threshold condition of 4/6/6/6/6, is only found among secondarily aquatic vertebrates with a flipper limb morphology and occurs exclusively in digits II and III among extant cetaceans [48]. Heterochrony appears to support the disproportionate elongation of digits II and III in cetaceans: the prolonged maintenance of a small section of apical ectodermal ridge (AER) distal to digits II and III drives elongation of these digits and extra joint patterning after the basic (terrestrial) digital pattern has been established and the other areas of the AER regressed (Fig. 11b–d) [49]. Developmental prerequisites for hyperphalangy also include lack of cell death in interdigital mesoderm, producing a flipper limb. A dynamic molecular pathway has been suggested, in which joint specification, interdigital cell death and digit elongation are mediated by interactions between BMPs, BMP antagonists and FGF signaling from the AER.

152

G. Barsacchi

Slight modifications of the pathway may explain how hyperphalangy develops. Thus, within cetaceans preservation of the interdigital cells and prolonged AER signaling maintain viable the digit specification pathway to provide the patterning mechanisms for formation of a limb apt to swimming. Heterotypy: change in type. Molecular changes in the very same developmental regulatory genes or gene networks can provide the proteins with new properties and may generate macroevolutionary changes in the morphology of organisms. One of such changes may explain why Insects have six legs only [50, 51]. About 400 My ago the Insect clade, provided with six legs only, split from the crustacean-like Arthropod ancestors, supplied with numerous legs. At present, in Drosophila melanogaster (and in other insects as well) the homeotic protein Ultrabithorax (Ubx) is expressed mainly in the abdominal segments, which are devoid of legs. In Drosophila, the protein Ubx possesses an alanin-rich aminoacid domain working as a repressor of transcription. This Ubx domain mediates repression of transcription of the gene distal-less in the Drosophila abdomen; since distalless is a master gene for formation of arthropod appendages, no legs develop from the fly’s abdomen. The alanin-rich domain is highly conserved among Ubx orthologues in Insects, but is absent from Ubx in other Arthropods and Onychophorans. In brachiopod Crustaceans endowed with many legs Ubx is expressed in both thorax and abdomen, where it does not inhibit the distal-less gene due to the lack, in its sequence, of the poly-alanin rich repressor domain. Therefore the unrepressed distal-less gene can activate formation of the many legs present along the crustacean trunk. Thus, the mutated Ubx gene, by acquiring an aminoacid domain able to repress the leg-forming distal-less gene in the Insect clade, may have mediated the evolutionary transition to the six-legs pattern of Exapods. The evolution of this domain may also have facilitated the great morphological diversification of posterior thoracic and anterior abdominal segments characteristic of modern Insects. This exemplifies heterotypy as a tinkering mechanism able to diversify animal morphology in evolution. Heterometry: an evolutionary change in the amount of some developmental entity. A change in the amount of a developmental gene product can also generate major morphological transitions. Heterometry appears to be involved in the extraordinary elongation of the digits that support the bat chiropatagium [52]. As mentioned above (Heterotopy), the earliest fossil bats resemble their modern counterparts and the lengths of the III-V digits (the primary supportive elements of the wing) have remained constant relative to body size over the last 50 million years. Investigating embryonic development, it was found that the digits in bats are initially similar in size to those of mice but that, subsequently, they greatly lengthen due to relatively high rates of chondrocyte proliferation and differentiation. A dramatic change in the intensity of Bmp2 expression and BMP signaling in the bat embryonic forelimb, relative to the bat hind limb and mouse forelimb stimulates cartilage proliferation and differentiation and increases digit length in the bat forelimb (see Fig. 10b). This species- and limb-specific change indicates that BMP2 has a major role in the


153

developmental elongation of bat wing digits. In addition, an up-regulation of the BMP pathway may potentially represent a key mechanism in the evolutionary elongation of bat forelimb digits. Heterometry has been beautifully demonstrated in the most celebrated example of adaptive evolution, the radiation of Darwin’s finches. Darwin’s finches are a group of about 14 closely related species on the Gala´pagos Islands and Cocos Island collected by Charles Darwin and others during the “Beagle” expedition in 1835. In 1839 Darwin wrote [53]: “The most curious fact is the perfect gradation in the size of the beaks in the different species of Geospiza, from one as large as that of a hawfinch to that of a chaffinch, and (. . .) even to that of a warbler. (. . .) Seeing this gradation and diversity of structure in one small, intimately related group of birds, one might really fancy that from an original paucity of birds in this archipelago, one species had been taken and modified for different ends.”

The finches have beaks of different sizes and shapes specialized for specific nutritional tasks: some species (ground finches) have stout beaks apt to cracking seeds; others (cactus finches) have slender, pointed bills apt for reaching into cactus flowers (Fig. 12a, b). Even small differences in any of the three major dimensions (depth, width and length) of the beak have major consequences for the overall fitness of the birds [54]. The specialized beak shapes are apparent at hatching and thus are genetically determined. A comparison of beak development in six species of Darwin’s finches belonging to the genus Geospiza revealed a striking correlation between beak morphology and level and timing of Bmp4 expression [55, 56]. In particular, a higher amount of Bmp4 is expressed in the primordium of the wider and deeper beak, while a lower expression of Bmp4 corresponds to a longer, thinner beak (Fig. 12b). In addition, artificially increasing BMP4 levels in the beak mesenchyme of a chick beak embryo, is sufficient to alter beak morphology in the same direction as is seen in the larger beaks of ground finches. Conversely, the calmodulin (CaM) protein – a molecule involved in mediating Ca2 signaling – is expressed at higher levels in the developing long and pointed beaks of cactus finches than in more robust beak types of other species [57]. When up-regulation of the CaM-dependent pathway is artificially replicated in the chick frontonasal prominence, it causes an elongation of the upper beak, imitating the beak morphology of the cactus finches (Fig. 12c, d). Thus, the CaM-dependent pathway is likely to have been a component of the evolution of Darwin’s finch species with elongated beaks. To sum up, observations and experimental results may provide an explanation on how tinkering with BMP4 and calmodulin regulation in the beak primordia provided the morphological variation acted on by natural selection in the evolution of the beaks of the Darwin’s finches. Furthermore, the fact that BMP4 and calmodulin act through two different signal transduction pathways may have contributed to the flexibility of beak conformation in the different birds during evolution. The exciting discoveries being made from studies on Darwin’s finches are a true celebration of Darwin’s legacy to modern science.

154

G. Barsacchi

a

c

b

Bmp4 expression

d

Fig. 12 Heterometry (and heterochrony, see text) in development of the beaks of Darwin’s finches. (a, b) Differential expression in the timing and amount of key molecular regulators of the beak formation during development appears to account for the different beak shapes of Geospiza species. (b) The represented species form two groups: ground (top) and cactus (bottom) finches, with distinct beak morphologies. At stage 29, Bmp4 (red arrows) is expressed at high levels in the distal beak mesenchyme of G. magnirostris, the species with the larger and deeper beak. Broad domains of Bmp4 expression are detectable around prenasal cartilages of G. fuliginosa and G. fortis. A small domain of strong Bmp4 expression is also found in the most distal mesenchyme of G. conirostris, and weaker expression is seen in G. scandens and G. fortis. (c, d) Functional analysis of CaMdependent pathway in beak development. Whole head views of day 10 chick embryos. (c) Wild-type. In (d), the CaM-dependent pathway was up-regulated and the beak was lengthened. The length of the beak is shown with a red line; the depth of the beak at the base and the depth of the beak at the tip are shown with blue and green lines, respectively. ((a) Kind gift of Prof. A. Abzhanov (b) adapted from [55]; courtesy of Prof. A. Abzhanov and with permission from A.A.A.S. (c, d) from [57]; courtesy of Prof. A. Abzhanov and with permission from John Wiley and Sons)

6 Conclusions Evolutionary Developmental Biology, or “Evo-Devo”, explores the relationships between the processes of individual development and the phenotypic changes of the organism during evolution. Evo-Devo is acknowledged to be revolutionizing our


155

understanding of how the development of organisms has evolved and of how development contributes to evolution. Methodological advances such as gene cloning, gene expression screening and visualization of gene activity in embryonic tissues facilitated the emergence of a major theme of the current Evo-Devo research, the evolutionary developmental genetics programme [58]. Its foundational achievement was the discovery of extensive similarities in developmental regulatory genes and gene networks among distantly related species. The programme concentrates on the evolution of genetic tool-kits and signaling pathways and on the regulatory logic that underlies organism development. Mapping the expression pattern of gene networks and signaling pathways and analyzing their correlation with the constructional features of body architecture, provides information on their possible role in phenotypic evolution. Major morphological transitions in evolution are presently recognized to be accommodated by a few key developmental genetic changes (part of a “developmental reprogramming” [1]) and “case studies” in snakes, ducks, bats, dolphins, insects, and finches, providing valuable insights into principles of evolutionary change, are presented. On the other hand, the molecular changes are rooted in an otherwise conserved developmental genetics tool-kit (e.g., the Hox genes for anterior-posterior patterning, the network for eye formation) that substantiates the “deep homology” underlying diversity of forms [12]. On this ground, the relationship of the deep homology of genes working through development with classic morphological homology is in the Evo-Devo field of exploration. Also, how environmental agents can instruct changes in development, for example altering gene expression – in a broad sense, searching for a link between genetic and environmental influences on development and the emergence of selectable phenotype variation – is in the perspectives of the newly growing and exciting discipline Ecological Developmental Biology (Eco-Devo), where Evo-Devo integrates with Ecology by examining the mechanisms of developmental regulation in an ecological context [59, 60]. We can expect that future work may further give reason for the Charles Darwin’s appraisal of the importance of Embryology for Evolution. Acknowledgements I regret that space constraints make it impossible to cite all relevant work and I therefore apologize to those whose work could not be cited. Additional references may be found in the cited papers. I am grateful to all Authors who were the source for this work and in particular to Prof. S.F. Gilbert, whose seminars and writings raised my interest in Evo-Devo. I wish to thank Prof. S.F. Gilbert and Prof. A. Abzhanov for their kind and generous gift of some pictures. I am also grateful to the Academies that organized the meeting on “The Theory of evolution and its impact” in Turin, May 27–29, 2010, for giving me the opportunity to present some of the present work in the genetics program of Evo-Devo.

References 1. Arthur W (2004) Biased embryos and evolution. Cambridge University Press, Cambridge 2. Darwin Francis (1887) The life and letters of Charles Darwin, including an autobiographical chapter, vol 2. John Murray, London

156

G. Barsacchi

3. Darwin CR (1859) On the origin of species by means of natural selection, or the preservation of favoured races in the struggle for life, 1st edn. John Murray, London 4. Darwin CR (1854) A monograph on the sub-class Cirripedia, with figures of all the species. The Balanidæ, (or sessile cirripedes); the Verrucidæ, etc. etc. etc, vol 2. The Ray Society, London 5. Darwin CR (1874) The descent of man, and selection in relation to sex, 2nd edn. John Murray, London 6. Delsuc F, Brinkmann H, Chourrout D, Philippe H (2006) Tunicates and not cephalochordates are the closest living relatives of vertebrates. Nature 439:965–968 7. Huxley TH (1893) Evolution in biology. Darwiniana. Collected essays. II. Macmillan, London 8. Huxley J (1942) Evolution: the modern synthesis. George Allan & Unwin, London 9. Jacob F (1977) Evolution and tinkering. Science 196:1161–1166 10. Carrol SB, Grenier JK, Weatherbee SD (2005) From DNA to diversity. Molecular genetics and the evolution of animal design, 2nd edn. Blackwell, Malden 11. Gilbert SF (2010) Developmental biology, 9th edn. Sinauer Associates, Sunderland 12. Shubin N, Tabin C, Carrol S (2009) Deep homology and the origin of evolutionary novelty. Nature 457:818–823 13. Salvini-Plawen LV, Mayr E (1977) On the evolution of photoreceptors and eyes. In: Hecht MK, Steere WC, Wallace B (eds) Evolutionary biology, vol 10. Plenum, New York, pp 207–263 14. Gehring WJ, Ikeo K (1999) Pax6: mastering eye morphogenesis and eye evolution. Trends Genet 15:371–377 15. Kumar JP, Moses K (2001) Eye specification in Drosophila: perspectives and implications. Semin Cell Dev Biol 12:469–474 16. Zuber ME, Gestri G, Viczian AS, Barsacchi G, Harris WA (2003) Specification of the vertebrate eye by a network of eye field transcription factors. Development 130:5155–5167 17. Kozmik Z, Daube M, Frei E, Norman B, Kos L, Dishaw LJ, Noll M, Piatigorsky J (2003) Role of Pax genes in eye evolution: a cnidarian PaxB gene uniting Pax2 and Pax6 functions. Dev Cell 5:773–785 18. Tomarev SI, Callaerts P, Kos L, Zinovieva R, Halder G, Gehring W, Piatigorsky J (1997) Squid Pax-6 and eye development. Proc Natl Acad Sci USA 94:2421–2426 19. Glardon S, Callaerts P, Halder G, Gehring WJ (1997) Conservation of Pax-6 in a lower chordate, the ascidian Phallusia mammillata. Development 124:817–825 20. Gehring WJ (2005) New perspectives on eye development and the evolution of eyes and photoreceptors. J Hered 96:171–184 21. Arendt D, Wittbrodt J (2001) Recostructing the eyes of Urbilateria. Phil Trans R Soc Lond B 356:1545–1563 22. Arendt D (2003) Evolution of eyes and photoreceptor cell types. Int J Dev Biol 47:563–571 23. Arendt D, Tessmar-Raible K, Snyman H, Dorresteijn AW, Wittbrodt J (2004) Ciliary photoreceptors with a vertebrate-type opsin in an invertebrate brain. Science 306:869–871 24. Arendt D (2008) The evolution of cell types in animals: Emerging principles from molecular studies. Nature 9:868–880 25. Kozmik Z, Ruzickova J, Jonasova K, Matsumoto Y, Vopalensky P, Kozmikova I, Strnad H, Kawamura S, Piatigorsky J, Paces V, Vlcek C (2008) Assembly of the cnidarian camera-type eye from vertebrate-like components. Proc Natl Acad Sci USA 105:8989–8993 26. Suga H, Schmid V, Gehring WJ (2008) Evolution and functional diversity of jellyfish opsins. Curr Biol 18:51–55 27. Gonza´lez-Meneńdez I, Contreras F, Cernuda-Cernuda R, Garcıá-Fernańdez JM (2009) Daily rhythm of melanopsin-expressing cells in the mouse retina. Front Cell Neurosci 3:1–7 28. Lim J, Choi K (2003) Bar homeodomain proteins are anti-proneural in the Drosophila eye: transcriptional repression of atonal by bar prevents ectopic retinal neurogenesis. Development 130:5965–5974 29. Poggi L, Vottari T, Barsacchi G, Wittbrodt J, Vignali R (2004) The homeobox gene Xbh1 cooperates with proneural genes to specify ganglion cell fate within the Xenopus neural retina. Development 131:2305–2315


157

30. Brown NL, Patel S, Brzezinski J, Glaser T (2001) Math5 is required for retinal ganglion cell and optic nerve formation. Development 128:2497–2508 31. Bateson W (1894) Materials for the study of variation treated with special regard to discontinuity in the origin of species. Macmillan, London/New York 32. Lemons D, McGinnis W (2006) Genomic evolution of Hox gene clusters. Science 313:1918–1922 33. Duboule D (2007) The rise and fall of Hox gene clusters. Development 134:2549–2560 34. De Robertis EM (2008) Evo-Devo: variations on ancestral themes. Cell 132:185–195 35. Yekta S, Tabin CJ, Bartel DP (2008) MicroRNAs in the Hox network: an apparent link to posterior prevalence. Nat Rev Genet 9:789–796 36. Cohn MJ, Tickle C (1999) Developmental basis of limblessness and axial patterning in snakes. Nature 399:474–479 37. Di-Poı¨ N, Montoya-Burgos JI, Miller H, Pourquie´ O, Milinkovitch MC, Duboule D (2010) Changes in Hox genes’ structure and function during the evolution of the squamate body plan. Nature 464:99–103 38. McGlinn E, Yekta S, Mansfield JH, Soutschekd J, Bartel DP, Tabin CJ (2009) In ovo application of antagomiRs indicates a role for miR-196 in patterning the chick axial skeleton through Hox gene regulation. Proc Natl Acad Sci 106:18610–18615 39. Graham A, McGonnell I (1999) Developmental evolution: this side of paradise. Curr Biol 9: R630–R632 40. Woltering JM, Vonk FJ, M€ uller H, Bardine N, Tuduce IL, de Bakker MA, Kn€ochel W, Sirbu IO, Durston AJ, Richardson MK (2009) Axial patterning in snakes and caecilians: evidence for an alternative interpretation of the Hox code. Dev Biol 332:82–89 41. Merino R, Rodriguez-Leon J, Macias D, Ganãn Y, Economides AN, Hurle JM (1999) The BMP antagonist Gremlin regulates outgrowth, chondrogenesis and programmed cell death in the developing limb. Development 126:5515–5522 42. Laufer E et al (1997) BMP expression in duck interdigital webbing: a reanalysis. Science 278:305 43. Cooper KL, Tabin CJ (2008) Understanding of bat wing evolution takes flight. Genes Dev 22:121–124 44. Weatherbee SD, Behringer RR, Rasweiler JJ, Niswander LA (2006) Interdigital webbing retention in bat wings illustrates genetic changes underlying amniote limb diversification. Proc Natl Acad Sci USA 103:15103–15107 45. Cretekos CJ, Wang Y, Green ED, Martin JF, Rasweiler JJ, Behringer RR (2008) Regulatory divergence modifies limb length between mammals. Genes Dev 22:141–151 46. Weatherbee SD (2008) Mammalian limbs take flight. Dev Cell 14:149–150 47. Wang Z, Yuan L, Rossiter SJ, Zuo X, Ru B, Zhong H, Han N, Jones G, Jepson PD, Zhang S (2009) Adaptive evolution of 50 HoxD genes in the origin and diversification of the cetacean flipper. Mol Biol Evol 26:613–622 48. Fedak TJ, Hall BK (2004) Perspectives on hyperphalangy: patterns and processes. J Anat 204:151–163 49. Richardson MK, Oelschl€ager HHA (2002) Time, pattern, and heterochrony: a study of hyperphalangy in the dolphin embryo flipper. Evol Dev 4:435–444 50. Ronshaugen M, McGinnis N, McGinnis W (2002) Hox protein mutation and macroevolution of the insect body plan. Nature 415:914–917 51. Galant R, Carroll SB (2002) Evolution of a transcriptional repression domain in an insect Hox protein. Nature 415:910–913 52. Sears KE, Behringer RR, Rasweiler JJ, Niswander LA (2006) Development of bat flight: morphologic and molecular evolution of bat wing digits. Proc Natl Acad Sci USA 103:6581–6586 53. Darwin C (1839) The voyage of the beagle. Natural history library, 1962nd edn. Anchor Press, Norwell 54. Grant PR, Grant BR (2008) How and why species multiply. The radiation of Darwin’s finches. Princeton University Press, Princeton

158

G. Barsacchi

55. Abzhanov A, Protas M, Grant BR, Grant PR, Tabin CJ (2004) Bmp4 and morphological variation of beaks in Darwin’s finches. Science 305:1462–1465 56. Wu P, Jiang T-X, Suksaweang S, Widelitz RB, Chuong C-M (2004) Molecular shaping of the beak. Science 305:1465–1466 57. Abzhanov A, Kuo WP, Hartmann C, Grant B, Grant PR, Tabin CJ (2006) The calmodulin pathway and evolution of elongated beak morphology in Darwin’s finches. Nature 443:563–567 58. Muller GB (2007) Evo–devo: extending the evolutionary synthesis. Nature 8:943–949 59. Gilbert SF, Epel D (2009) Ecological developmental biology. Integrating epigenetics, medicine and evolution. Sinauer Associates, Sunderland 60. Minelli A, Fusco G (eds) (2008) Evolving Pathways. Key themes in evolutionary developmental biology. Cambridge University Press, Cambridge, UK

Evolutionary Mechanisms and Neural Adaptation: Selective Versus Constructive Strategies in the Development and Plasticity of the Nervous System Ferdinando Rossi

Abstract The correct function of the nervous system requires complex neural networks bearing precise connections. In principle, the high structural specificity of neural circuits could be achieved by genetically-determined processes, selected and refined during evolution. Highly conserved gene networks regulate some crucial steps of neural development, such as the regionalization of the neural tube and the initial phases of neurogenesis and synaptogenesis. A totally hardwired nervous system may meet the requirements of adaptation and natural selection at the population level. Nevertheless, it would be inadequate to allow individual organisms to cope with rapid changes of environmental conditions. Neural adaptation to external constraints can be partly achieved by introducing selective mechanisms in neural development. Accordingly, neurons are generated in excess and then partially eliminated to match the actual extension of innervation territories. Such mechanisms, however, are restricted to a set of potentialities, which must be predetermined in the ontogenetic program. On the other hand, constructive mechanisms, in which external stimuli directly influence structural modifications of neural circuits to produce adaptive responses, may allow individual organisms to cope with a wide variety of unprecedented situations. Thus, in the last ontogenetic period as well as in the adult, when the organism actively interacts with the external milieu, experience exerts a strong growth-promoting effect on neural circuits and connections inducing the emergence of specific functional properties. By this mechanism, which requires strict inhibitory control to prevent aberrant growth and dysfunction, the nervous system exploits external stimuli to create adaptive responses to unexpected situations.

F. Rossi (*) Department of Neuroscience, Section of Physiology, University of Turin, Orbassano, Torino, Italy e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_10, # Springer-Verlag Italia 2012

159

160

F. Rossi

1 Introduction Over the last decades, substantial advancements have been obtained in the elucidation of the cellular and molecular interactions that regulate the development of the nervous system, govern its function and determine its plastic capabilities in adulthood. These discoveries have led to the proposition of concepts and principles that relate, in a very peculiar manner, developmental neurobiology and neurophysiology to evolution. In addition to the obvious influence exerted by evolutionary processes on neural ontogenesis and on neurobiological mechanisms [57], this novel relationship stems from the understanding that both the construction of the nervous system and its operation are continuously scrutinized for their efficacy in enabling the organism to cope with environmental demands. Hence, the notion that neural development and plasticity represent the biological substrates of adaptation has led to propose that these processes are regulated by fundamental mechanisms that are shared with Darwinian evolution and, notably, the mechanisms of natural selection [8, 13]. This concept originated from the discovery that some fundamental ontogenetic phenomena, such as the formation of appropriate numbers of neurons or synapses in the brain, are subjected to environmental constraints, in a way that is reminiscent of the regulation of population size in living organisms. For instance, there is now general agreement that most neuron populations are initially generated in excess and attain their final numbers by a process of cell elimination, in which death or survival depend on the extension of innervation territories, the availability of targetderived trophic substances or the level of neuronal activity [27, 47]. Similar considerations are usually applied to synaptogenesis, where initially exuberant contacts are progressively withdrawn according to a set of restrictive parameters, including levels of activity, spatio-temporal patterns of synaptic activation or activity-dependent uptake of neurotrophic factors [27, 62]. This large body of evidence highlights the role of selective mechanisms in aspects of neural development and plasticity that are strictly related to adaptation. Nevertheless, a purely selective mechanism implies a range of pre-existing potentialities, which is restricted following confrontation with intervening demands. In other words, all the available options should be hardwired ex ante in the ontogenetic program responsible for constructing the organism. Now, is such a mechanism really compatible with adaptation? How can the variety of pre-existing potentialities be expanded at an adequate pace to match the speed of environmental change? Are the discarded options permanently lost or can they be rescued if they become again advantageous in the future? A selective strategy is primarily designed to control adaptation at the population level. Hence, it is most efficient in regulating species evolution or, as we will discuss later, in defining the number of neurons belonging to a certain category. On the other hand, the main goal of neural adaptation is to allow individual organisms to cope with changing environmental conditions. A closer examination of neural development and plasticity in this perspective actually suggests that the nervous

Evolutionary Mechanisms and Neural Adaptation

161

system must be endowed with an intrinsic capability to construct neural circuits so to create novel functional properties, beyond the original set of potentialities. As a consequence, both selective and constructive mechanisms participate to determine neural ontogenesis and plasticity. Constructive strategies, however, prevail over selective ones when the individual nervous system has to face contextual environmental demands.

2 Adaptive Mechanisms Can Be Either Predictive or Reactive Biological modifications set up to cope with environmental changes occur according to two main modes. On one side, the organism is able to predict the incoming variation and builds up an anticipated response. On the other, the organism is unable to foresee the external change and it can only react to novel conditions once they have been established. Thus, predictive adaptation implies that the organism is ready to face the novel environmental demand at the time when it materializes, whereas reactive adaptation will be only unfolded in a subsequent time. At a first glance, predictive adaptation may appear more efficient in favouring survival of the organism. Nonetheless, it can be only used in a restricted set of situations. Actually, predictive mechanisms are only suitable to face extrinsic changes that happen at a constant pace through a long period of time (essentially forever). Organisms that spontaneously acquire predictive abilities are favoured over their counterparts and, hence, these abilities become selected by evolutionary mechanisms. Accordingly, predictive adaptation is usually sustained by highly conserved gene networks, whose spatio-temporal patterns of activation correspond to the time course or space distribution of the related environmental conditions. The best example of this kind is the regulation of circadian and circannual functions [12, 19]. These functions are operated by molecular cascades endowed with intrinsic rhythms that match the duration of relevant environmental periods, to which they become entrained by sensory information. As we will discuss here, predictive mechanisms operate in some major ontogenetic processes, which are also governed by highly conserved gene programs. For instance, the gene networks that direct the building of the body (and neural) plan have clearly evolved to cope with consistent environmental constraints, such as gravity, the sources of energy or relevant sensory information (e.g. sunlight) or the mechanics of movement. Albeit successful, predictive strategies take very long times to become established and diffused. In addition, it is clear that the vast majority of environmental changes happen according to completely unpredictable frequencies and locations. Such situations can be adequately faced only by means of reactive processes, which allow individual organisms or populations to design and set up novel responses. In these cases, evolutionary processes favour the emergence and maintenance of certain abilities, but leave ample degrees of freedom in their actual expression. Most homeostatic mechanisms work in this way. For instance, body temperature is maintained by a series of evolutionary-selected interdependent

162

F. Rossi

devices, from thyroid hormones to horripilation, whose function is triggered and modulated by feedback loops that tune every response to the concomitant situation. The vast majority of external conditions that may influence the function of the nervous system belong to the latter category. More, I would say that the main emerging property of the nervous system is to design novel strategies to solve unprecedented problems. Accordingly, neural cells and circuits must be endowed with the ability of reshaping connectivity so to generate new functional capabilities that are not part of the constitutive repertoire of the species. Acquiring new information or learning new skills are examples of this sort of morpho-functional modification that underlies neural adaptation. Hereafter, I will argue that these processes, that are crucial to regulate neural development and plasticity, cannot be solely explained in terms of selective mechanisms, but require constructive properties that allow the creative design of new adaptive strategies.

3 Neural Development and Evolutionary Mechanisms In the perspective of this essay, neural development can be schematically subdivided in three main phases (Fig. 1): (1) neurulation refers to the formation of the neural tube and its segmentation into discrete morphogenic regions; (2) neurogenesis is the process by which neurons (and glia) are generated; (3) synaptogenesis is the process by which neurons become connected to each other into functional circuits. These phases comprise both addition (e.g. generation of new neurons, formation of new synapses) and loss of elements (e.g. physiological cell death, synaptic pruning). Therefore, the growth of the nervous system actually results from the balance of concurrent expansive and regressive phenomena. Neurulation is triggered by inductive signals issued by the notochord, a mesodermal structure lining the rostro-caudal axis of the embryo, which triggers profound morphogenic rearrangement of the overlying ectoderm leading to the formation of the neural tube [3, 27]. The latter is a highly polarised structure, which soon becomes subdivided in discrete domains that acquire distinctive morphofunctional specification along the main spatial axes (Fig. 1) [3, 27]. The most important partition occurs along the rostro-caudal axis, where morphologically distinct segments appear, corresponding to the major subdivisions of the adult Central Nervous System (CNS). Within each of such segments, the dorso-ventral axis defines sensory or motor structures, whereas the medio-lateral axis defines the relationship linking neural circuits to axial structures (the trunk) and distal appendages (the limbs). The regionalization and spatial specification of the neuraxis are determined by the interplay between diffusible or contact signalling cues and the combinatorial expression of specific sets of transcription factors [3]. The whole process is regulated by gene networks, which direct the morphogenesis of the entire body plan. This gene program has been particularly successful during evolution: it has been inherited from invertebrates and it is highly conserved through the phyla of


163

Fig. 1 Regulatory mechanisms of neural ontogenesis. The early phases of nervous system development are determined by the execution of a gene program that directs neurulation, the regionalization of the neural tube, the generation of nerve cells and the initial formation of synapses. While these processes are regulated in a predictive manner, later phases are accomplished according to reactive strategies, required to adapt ontogenetic processes to contextual environmental conditions. Surplus neurons are eliminated before birth by a selective mechanism depending on the extension of available innervation territories. On the other hand, synaptogenesis is carried out after birth, when the organism is interacting with the external world. Hence, synapse formation and reshaping are governed by experience-dependent constructive mechanisms

vertebrates [51]. The program assembles a structural scaffold, in which fundamental morphogenic interactions are precisely regulated in space and time, securing the coordinate development of intrinsic neural networks and their appropriate integration within the nascent organism. On this basic canvas, evolution creates diversity by introducing domain-specific variations in the rate of growth and in the connection patterns. In this way, birds have a relatively large mesencephalon, whereas mammals are characterized by a prominent telencephalon. Thus, neural morphogenesis is accomplished, in a predictive manner, by the intrinsic activity of specific gene networks, whose success is determined a posteriori by natural selection.

164

F. Rossi

Neurogenesis, which is obviously interrelated with morphogenesis, comprises all the phenomena leading to the generation of neurons and glia from neural stem and progenitor cells (Fig. 1) [27]. These cells proliferate in germinal structures located at different levels along the neuraxis, become specified towards different identities and migrate to specific locations, where they acquire mature phenotypes. Then, the final size of each neuronal population can be refined through physiological cell death. The generation of phenotypic diversity is largely determined by diffusible molecular cues or cell-to-cell interactions that regulate the expression of particular combinations of transcription factors [14, 22, 37, 39]. Once cell fate choices have been taken, however, the differentiation into mature phenotypes is achieved by the unfolding of type-specific gene programs, in an essentially cellautonomous manner. Hence, neuronal differentiation as well as the establishment of the basic framework of connectivity are also governed by predictive mechanisms that determine a priori the capability of a given neuron to migrate into a certain position, orientate the navigation of its axon or recognize appropriate targets. The situation is different when the regulation of neuron numbers is considered (Fig. 1). The number of neurons generated for each category is determined by the interplay between intrinsic properties of neural progenitors and local regulatory interactions that modulate the rhythm of proliferation, the relative proportion of cells that initiate differentiation or continue to divide, and the duration of neurogenic periods [7, 33]. All these mechanisms operate to regulate neuron numbers by adjusting their production and, hence, work according to a predictive strategy. Nevertheless, since the pioneering work of Rita Levi-Montalcini and Giuseppe Levi [30], it is well known that most neuron populations are actually generated in excess and the final amount of nerve cells that populate the mature nervous system is achieved through the elimination of supernumerary elements [42]. Cell death or survival depend on a set of parameters, including both intrinsic features of the neurons (e.g. their level of activity) and environmental constraints (e.g. the extension of the target field or the availability of neurotrophic substances). This process is suitable to match the size of each neuronal population to the amount of potential synaptic partners or to the extension of innervation territories in the periphery. It operates according to a selective mechanism that is most reminiscent of natural selection: the juvenile neurons compete for limited quantities of available resources and their fate depends on their intrinsic ability to overcome their rivals [8, 47]. In this case, however, the mechanism works following a reactive strategy, required to adjust neural development to individual fluctuations in the dimension of different parts of the body. Accordingly, the size of most neuron populations can be significantly modified by experimental manipulations that increase or reduce the extension of the available innervation territory [27, 42, 44]. Therefore, the final number of neurons belonging to each population derives from a dual mechanism, which combines a predictive component, that determines the initial production of surplus neurons, and a reactive component, that eliminates supernumerary elements in response to contextual environmental conditions. At a first glance, similar mechanisms may apply during synaptogenesis (Fig. 1). A well-established notion in developmental neurobiology is that synapses are


165

initially formed in excess and then partially withdrawn to shape the mature connectivity [27, 47]. Since effective function of neural circuits depends both on the number and on the specificity of synapses, the pruning process would be required both to reduce the exuberant, supernumerary contacts and to remove aberrant, wrong connections. The initial formation of synapses is guided by recognition cues exposed on the neuronal membrane, whose nature is determined by the intrinsic neurochemical profile of the partner neurons [5, 61, 66]. Synaptic pruning is driven by activitydependent mechanisms that are directly influenced by the functional efficacy of the developing circuitry [8, 47]. Thus, synaptogenesis also appears to depend on a dual mechanism. Synapse formation is guided by molecular interactions determined by the unfolding of neuronal-intrinsic gene programs that work in a predictive manner. On the other hand, synaptic pruning is driven by an essentially reactive mechanism that selects good connections on the basis of their functional meaningfulness. Again, the latter phenomenon appears to follow some fundamental principles of natural selection. The analogy is partial at best. It is well established that a number of synapses are withdrawn to shape appropriate spatial connection patterns on specific target domains. Nonetheless, it is definitely clear that, when the number of contacts and/ or their functional weight is considered, the final balance of the synaptogenic process is a positive one: newly-formed synapses greatly outnumber the lost ones [46, 49, 62]. This has been clearly demonstrated in a variety of experimental models, including the autonomic nervous system [31, 48], the visual system [60], or the cerebellar climbing fibres [23], just to cite a few ones. Even in the case of the neuromuscular junction where mono-innervation of muscle fibres appears to be solely achieved through the elimination of supernumerary axons, the winner endplate undergoes a remarkable outgrowth to cover the entire postsynaptic surface with additional junctional complexes and releasing sites [46, 55]. Therefore, the reactive component of synaptogenesis is not a selective process, but rather operates in a constructive manner. This conclusion has profound implications in terms of structure-to-function relationship during neural development. Indeed, while the initial formation of synaptic contacts is essentially aimed at establishing a basic framework of neural networks capable of initiating the interaction with the external world, the refinement phase is aimed at modifying the structure of such networks to improve their operational abilities. Thus, a fundamental circuit scaffold, assembled by executing intrinsic gene programs, is confronted with experience and modified to achieve adaptive function. The latter process involves the elimination of some unspecific contacts, but it is primarily characterized by the strengthening of meaningful connections with the addition of numerous new synapses. This process of structural remodelling, which involves the simultaneous outgrowth of both presynaptic axons and postsynaptic dendrites [44, 48], leads to the emergence of novel functional properties, whose nature is influenced by the specific features of the contextual environmental conditions. In other words, the final structure of neural circuits is congruent with the actual experience: a particular

166

F. Rossi

interaction with the external world will always lead to an appropriate pattern of connectivity [53]. The essentially constructive nature of this process can be best appreciated in extreme experimental conditions. For instance, severe manipulations such as monocular deprivation or experimental squid during the critical periods of visual system development induce extensive changes in the connectivity of the subcortical and cortical visual pathways [60]. This peculiar structure, albeit strongly divergent from that of the normal population, is clearly adaptive when the visual experience of the relevant individuals is considered. Indeed, there is no reason to leave half of the cortical territory to an eye that is not conveying any significant sensory information. Similarly, there is no use to form binocular connections if the two eyes are seeing different scenes. Yet, it is difficult to believe that such unusual projection patterns result from the selection of pre-existing connections, rather than being actively constructed by adapting the morpho-functional properties of the circuit to real life experience. Similar considerations apply to other systems, such as the peculiar tonotopic representation that can be induced in the auditory cortex by exposure to auditory stimuli of specific frequencies [10]. On the whole, the initial phases of nervous system development, which include neural morphogenesis, neuronal production and the establishment of basic connection patterns, are directed by the activity of species-specific gene networks that operate according to an essentially predictive strategy. These processes lead to assemble the fundamental framework of the nervous system, which then undergoes individual-specific morpho-functional adaptation according to reactive strategies. Neuron numbers are refined through a primarily selective process, whereas synaptic patterns are reshaped according to constructive mechanisms. The latter mechanisms have been likely evolved to exploit influences derived from contextual experience to favour the development of adaptive function.

4 Experience-Dependent Mechanisms, Neural Development and the Emergence of Function A major feature of the last phases of neural development is the appearance of reactive processes that essentially shift adaptation from species to individuals. Such processes, however, are accomplished during distinct ontogenetic phases, characterized by strongly different conditions [27, 46]. Neurogenesis and physiological cell death primarily occur before birth and are influenced by somatic changes taking place within the same developing organism. On the other hand, the bulk of synaptogenesis is carried out after birth, while the newborn organism is actively interacting with the external world. The latter condition exerts a most dramatic influence on the course and on the outcome of this process. Higher vertebrates, notably mammals, are born with immature neural circuits, and this feature is most prominent in primates and humans [45, 57]. This implies that crucial phases of neural development occur while the organism is exposed to


167

Fig. 2 External stimuli direct developmental synaptogenesis and adult circuit plasticity. External stimuli drive plastic modification of neural circuits by inducing neuritic remodelling and directing the formation of functionally meaningful contacts. The process is regulated by inhibitory cues present in the CNS microenvironment (represented by the STOP signals), required to prevent aberrant growth and dysfunction

the external environment rather than sheltered in an egg or in the uterus. The newborn CNS, and particularly those structures that are more immature at birth such as the neocortex, is subjected to a wide range of powerful stimuli, which induce specific patterns of neuronal activation, stimulate neuritic extension and influence the number and the distribution of newly-formed synapses [63]. This ability of experience to stimulate neural growth is the crucial event that shifts the nature of synaptogenesis from a selective process aimed at achieving synaptic specificity to a constructive one capable of building new functionally meaningful connections (Fig. 2). Sensory deprivation experiments, such as dark rearing or exposure to unmodulated acoustic stimulation [11, 60, 65], show how administration of meaningful stimuli immediately activates neuronal growth mechanisms, associated with rapid acquisition of new functional properties. All these examples of experience-dependent structural remodelling are characterized by a clear prevalence of expansive phenomena, with the formation and strengthening of new synapses, over regressive events and loss of contacts. Hence, experience drives neuronal growth to create adaptive function. The evolutionary advantage of this strategy is obvious: each individual organism capable of exploiting contextual experience to generate appropriate novel responses will be able to successfully cope with a wide range of unprecedented situations. Once function is acquired, synaptogenic processes are greatly reduced if not completely arrested [24]. This decline of neuronal growth properties, that marks the end of developmental critical periods for the acquisition of experience-dependent capabilities, has been attributed to a set of concurrent mechanisms. The remodelling of neural circuits often leads to a substantial segregation of afferent axons, which impinge upon private target domains, being individual dendrites, single neurons or discrete anatomical modules. This process of input segregation would progressively reduce the need and the opportunity for activity-dependent competitive interactions that sustain synaptogenesis [62]. Hence, growth would be arrested when a stable connection pattern is achieved and all partners had their share.

168

F. Rossi

In spite of the attractive simplicity of this mechanism, the end of synaptogenic processes is actually coincident with profound modifications that occur in the neurons themselves and in the surrounding microenvironment [53]. Within the nerve cells, growth-associated gene programs are actively suppressed to favour information processing and signalling function. Coincidentally, the maturation of glia, namely myelination, and the deposition of the extracellular matrix are accompanied by the appearance of a variety of growth-inhibitory molecules that stabilize contacts and hamper further elongation of neuronal processes (Fig. 2). These phenomena are precisely aimed at restricting growth properties of neural circuits. As we will see in the next section, synaptogenic properties typical of juvenile organisms can be restored in the mature CNS by specific manipulations that boost intrinsic neuronal growth properties or remove environmental inhibition. The presence of such strict growth control mechanisms, which have been progressively implemented during the evolution of vertebrates [17, 56], represents an additional argument favouring the constructive nature of developmental synaptogenesis. Indeed, a purely selective mechanism is self-limiting and does not require additional regulatory devices to be terminated. On the contrary, a constructive mechanism must be actively arrested, either by removing the sustaining stimuli or by dampening growth processes. Experience cannot be prevented or abolished: the whole ontogenetic process is precisely aimed at making the nervous system able to cope with external constraints. Therefore, when the development of neural circuits adopted the constructive strategy driven by experience-dependent stimulation, a set of growth-inhibitory mechanisms evolved to stabilize meaningful connections and to restrain neuronal growth once function is achieved. Not surprisingly, the induction of such regulatory molecules is also triggered by experience [26, 59].

5 Constructive Mechanisms and Plasticity in the Adult In spite of the clear decline of intrinsic neuronal growth potentialities, after the end of canonical ontogenesis the nervous system retains a certain degree of ability to modify his structure and function in response to external stimuli or changes in the environment. Adaptation in the mature nervous system, which is generally known as plasticity, shares some fundamental features and mechanisms with developmental processes. The notion of plasticity in the adult CNS was established several decades ago with the discovery of reactive synaptogenesis and synaptic turnover [9, 50]. Accordingly, for a long time the adaptive abilities of neural circuits were thought to be exclusively sustained by changes of connectivity. Recently, however, the demonstration that neurogenesis persists at least in some regions of the adult mammalian brain has revealed that functional adaptation can be also carried out by integrating new neurons in pre-existing circuits. Compared to neural development, synaptogenic phenomena occurring in the adult nervous system are considerably restricted in space and time. They involve


169

both formation and withdrawal of synaptic contacts and, although they usually lead to moderate changes of synaptic numbers, they obey to reactive mechanisms and have a clear constructive character. One important difference with juvenile synaptogenesis is the requirement of active participation [29, 64]. Synaptic remodelling in immature organisms is usually triggered by the mere exposure to external stimuli. In contrast, in adulthood plastic changes also require motivation and active participation of the involved organism. Hence, in mature individuals adaptation is no more an automatic response to environmental conditions, but requires an individual volition that determines the nature of the response and influences its outcome. Plasticity in the adult is strongly hampered by the presence of the abovementioned inhibitory mechanisms that terminate developmental synaptogenesis. These mechanisms are partially counteracted by the growth promoting effect exerted by external stimuli [18, 20, 54]. Accordingly, structural plasticity and functional adaptation in the adult can be conspicuously enhanced by experimental procedures that activate neuronal growth genes or neutralize inhibitory molecules of the CNS microenvironment [53]. Nevertheless, whatever effective the simple manipulation of the molecular devices that control neuritic growth is not sufficient to induce adaptation. Endurable structural changes associated with significant functional modifications can only be established if these procedures are combined with specific environmental stimuli [43]. Hence, growth regulatory mechanisms exert a purely permissive role by setting the degree of plasticity of neural circuits, whereas environmental stimulation has a primarily instructive function in determining the shape of the connectivity that will be formed [53]. These features are consistent with a reactive mechanism that induces structural remodelling of neural circuits to generate adaptive responses. As for developmental synaptogenesis, the presence of multiple inhibitory mechanisms is required to maintain constructive modifications within the limits of adaptive function. Indeed, there are several examples showing that altered regulatory mechanisms and/or unusual experience may induce unspecific growth associated with frank pathological phenomena, such as seizures or dystonia [1, 6, 40]. A selective mechanism may fail to generate an adaptive response if the required option is not available, but it should be intrinsically unable to produce abnormal structures and aberrant function. Thus, plasticity in the adult also follows a constructive strategy and, for this reason, it must be subjected to inhibitory control. Adult neurogenesis shares its major functional significance with adult plasticity. In some CNS structures adaptation is not exclusively sustained by changes of connectivity, but also involves the integration of newly generated neurons into pre-existing circuits. As discussed above, developmental neurogenesis comprises a predictive mechanism that generates excessive amounts of neurons, whose final number is defined by a reactive mechanism that operates through selection. The scenario of adult neurogenesis is very different. In both regions of mammalian brain where new neurons are generated throughout life, the hippocampal dentate gyrus and the olfactory system, the rate of neuronal generation is clearly influenced by external stimuli and/or activity-dependent mechanisms [15, 35]. Thus, while the

170

F. Rossi

adult system retains the capacity for generating neurons, the course and outcome of the process are no more determined by an intrinsically-coded predictive mechanism, but regulated by extrinsic cues according to a reactive strategy. Many of the newly generated neurons survive only for a short time, suggesting that survival may depend on selective mechanisms, as for developmental neurogenesis. However, the number and the specific features of the neurons that eventually become stably integrated in adult circuits depend on the activity of the involved network and on specific functional demands [2, 28, 32, 41]. In other words, integration of the newborn neuron is directly related to the function that is being established and not to the intrinsic receptive capacity of the system. Therefore, similar to synaptic remodelling, adult neurogenesis appears to work as a reactive device obeying to a primarily constructive strategy. This conclusion is further supported by the observation that neurogenesis, or at least neurogenic attempts, may be induced in other regions of the CNS by strong stimulation or pathological conditions [4, 34, 52, 58]. In these instances, nonneurogenic structures react to extreme environmental constraints by redirecting the specification of local progenitors towards neuronal lineages. These phenomena of intraparenchymal neurogenesis are often abortive, because non-neurogenic regions fail to provide adequate conditions to support the differentiation and integration of new neurons. Hence, latent neurogenic potentialities may be diffused in many CNS regions, but actively repressed by local constraints. In any case, adult neurogenesis appears to be driven by environmental stimuli influencing the mature tissue, rather than local regulatory cues acting in a primary germinal structure. Another feature that adult neurogenesis shares with adult plasticity is the presence of strict inhibitory control. Intrinsic inhibitory control prevents adult neurons from de-differentiating or re-entering the cell cycle [25]. In addition, environmental cues regulate the proliferation of progenitors as well as the migration, differentiation and integration of newborn neurons [38]. Thus, successful incorporation of new neurons in adult networks is restricted to precise phenotypes in defined circuits. Furthermore, transplantation experiments show that the endogenous ability of the adult CNS to accommodate donor neurons in functional circuits is limited to a few types and locations [21, 36]. These inhibitory constraints also appear to be primarily aimed at preventing aberrant phenomena that may lead to maladaptive function or behaviour. However, these considerations indicate that adult neurogenesis also has the main characters of a reactive/constructive process, in which experience-dependent growth is exploited to modify neural structures so to achieve adaption.

6 Conclusions The initial phases of neural development are primarily regulated by predictive mechanisms that have been established by evolution. These processes, which are highly conserved throughout vertebrate phylogenesis, are designed to develop a nervous system that is suitable to control the main bodily functions of the organism


171

and is capable of interacting with the external world. The sensitivity of neural circuits to external stimuli, however, profoundly influenced the strategy of neural development. When coping with rather constant phenomena, such as the physiological expansion or retraction of different body parts, suitable adaptation can be obtained by merely selective mechanisms, which share some features with natural selection. Hence, neurogenesis starts with the production of surplus neurons and their final number is adjusted to match actual requirements, which may fluctuate among individuals, but always remain within predictable ranges. A similar mechanism may also apply to synaptogenesis if the nervous system was designed to be completely hardwired by intrinsic genetically-determined mechanisms. Quite surprisingly, however, the exposure of the immature nervous system to the external environment dramatically changed the ontogenetic strategy. Now, the ability of coping with a great variety of unpredictable environmental constraints could not be adequately fulfilled by a selective process. Rather, the expanding variety of situations favoured the emergence of an alternative mechanism, able to create unprecedented structure and function to face unprecedented situations. Thus, evolutionary pressure pushed developmental synaptogenesis, adult plasticity and even adult neurogenesis to become reactive processes obeying to the rules of constructive mechanisms. This constructive revolution of neural ontogenesis induced the appearance of specific regulatory mechanisms, which evolved to restrain the unchained growth driven by external stimuli within the limits of adaptive function. These inhibitory cues first appeared in fish and amphibians [56], but their importance consistently increased during later vertebrate evolution, in parallel with the increasing complexity of CNS structure and function. Now, they clearly fulfil the fundamental task of controlling potentially dangerous growth properties that enable the nervous system of powerful plastic and adaptive capabilities. However, they also bring with themselves some relevant side effects, such as the loss of neural regeneration capabilities [16, 17]. In any case, constructive mechanisms, such as those directing adult plasticity and neurogenesis, represent a most successful phylogenetic invention that greatly increased the individual ability to cope with increasingly wide ranges of environmental conditions. Acknowledgements The scientific work of Ferdinando Rossi is supported by grants from Ministero dell’Universita` e della Ricerca Scientifica e Tecnologica (MIUR-PRIN 2007 prog. nr. 2007F7AJYJ), Compagnia di San Paolo (Neurotransplant Project 2008; GABAGEN Neuroscience project 2009), Regione Piemonte (Project A14/05; Ricerca Sanitaria Finalizzata, 2008, 2009), Ataxia UK; Fondazione Cavaliere del Lavoro Mario Magnetto of Turin.

References 1. Aigner L, Arber S, Kapfhammer JP, Laux T, Schneider C, Botteri F, Brenner H-R, Caroni P (1995) Over expression of the neural growth associated protein GAP-43 induces nerve sprouting in the adult nervous system of transgenic mice. Cell 83:269–278 2. Aimone JB, Deng W, Gage FH (2010) Adult neurogenesis: integrating theories and separating functions. Trends Cogn Sci 14:325–337

172

F. Rossi

3. Bronner-Fraser M, Hatten ME (2003) Neural induction and pattern formation. In: Squire LR, Bloom FE, McConnell SK, Roberts JL, Spitzer NC, Zigmond MJ (eds) Fundamental neuroscience. Academic, New York/London 4. Brundin P, Winkler J, Masliah E (2008) Adult neurogenesis in neurodegenerative diseases. In: Gage FH, Kempermann G, Song H (eds) Adult neurogenesis. Cold Spring Harbor Laboratory Press, Cold Spring Harbor, pp 503–533 5. Burden SJ, Berg D, O’Leary DDM (2003) Target selection, topographic maps and synapse formation. In: Squire LR, Bloom FE, McConnell SK, Roberts JL, Spitzer NC, Zigmond MJ (eds) Fundamental neuroscience. Academic, New York/London 6. Byl N, Merzenich MM, Jenkins WM (1996) A primate genesis model of focal dystonia and repetitive strain injury. I. Learning-induced dedifferentiation of the representation of the hand in the primary somatosensory cortex in adult monkeys. Neurology 47:508–520 7. Caviness VS Jr, Nowakowski RS, Bhide PG (2009) Neocortical neurogenesis: morphogenetic gradients and beyond. Trends Neurosci 32:443–450 8. Changeux JP (1983) L’homme neuronal. Fayard, Paris 9. Cotman C, Sampedro N, Harris EW (1981) Synapse replacement in the nervous system of adult vertebrates. Physiol Rev 61:684–784 10. De Villers-Sidani E, Chang EF, Bao S, Merzenich MM (2007) Critical period window for spectral tuning defined in the primary auditory cortex (A1) in the rat. J Neurosci 27:180–189 11. De Villers-Sidani E, Simpson KL, Lu Y-F, Lin RCS, Merzenich MM (2008) Manipulating critical period closure across different sectors of the primary auditory cortex. Nat Neurosci 11:957–965 12. Dunlap JC, Loros LJ, De Coursey P (2004) Chronobiology: biological timekeeping. Sinauer, Sunderland 13. Edelman G (1987) Neural Darwinism. The theory of neuronal group selection. Basic Books, New York 14. Edlund T, Jessell TM (1999) Progression from extrinsic to intrinsic signaling in cell fate specification: a view from the nervous system. Cell 96:211–224 15. Fabel K, Kempermann G (2008) Physical activity and the regulation of neurogenesis in the adult and aging brain. Neuromolecular Med 10:59–66 16. Fawcett JW, Rosser AE, Dunnett SB (2002) Brain damage, brain repair. Oxford University Press, Oxford 17. Ferretti P, Zhang F, O’Neill P (2003) Changes in spinal cord regenerative ability through phylogenesis and development: lessons to be learnt. Dev Dyn 226:245–256 18. Foscarin S, Ponchione D, Pajaj E, Leto K, Gawlak M, Wilczynski GM, Rossi F, Carulli D (2011) Experience-dependent plasticity and modulation of growth regulatory molecules at central synapses. PLoS One 6:e16666 19. Foster RG, Kreitzman L (2004) Rhythms of life: the biological clocks that control the daily lives of every living thing. Profile Books, London 20. Gomez-Pinilla F, Ying, Z, Agoncillo T, Frostig R (2011) The influence of naturalistic experience on plasticity markers in somatosensory cortex and hippocampus: effects of whisker use. Brain Res 1388:39–47 21. Grimaldi P, Carletti B, Rossi F (2005) Neuronal replacement and integration in the rewiring of cerebellar circuits. Brain Res Rev 49:330–342 22. Harris WA, Hartenstein V (2003) Cellular determination. In: Squire LR, Bloom FE, McConnell SK, Roberts JL, Spitzer NC, Zigmond MJ (eds) Fundamental neuroscience. Academic, New York/London 23. Hashimoto K, Hichikawa R, Kitamura K, Watanade M, Kano M (2009) Translocation of a “winner” climbing fiber to the Purkinje cell dendrite and subsequent elimination of “losers” from the soma in developing cerebellum. Neuron 63:103–118 24. Hensch T (2004) Critical period regulation. Annu Rev Neurosci 27:549–579 25. Herrup K, Yang Y (2007) Cell cycle regulation in the postmitotic neuron: oxymoron or new biology? Nat Rev Neurosci 8:368–378


173

26. Hockfield S, Kalb RG (1993) Activity-dependent structural changes during neuronal development. Curr Opin Neurobiol 3:87–92 27. Jacobson M (1991) Developmental neurobiology. Plenum, New York/London 28. Kempermann G, Fabel K, Ehninger D, Babu H, Leal-Galicia P, Garther A, Sa W (2010) Why and how physical activity promotes experience-induced brain plasticity. Front Neurosci 4:189 29. Keroughlian AS, Knudsen EI (2007) Adaptive auditory plasticity in developing and adult animals. Prog Neurobiol 82:109–121 30. Levi-Montalcini R, Levi G (1944) Correlazioni nello sviluppo tra varie parti del sistema nervoso. Pont Acad Sci 8:527–568 31. Lichtman JW (1977) The reorganization of synaptic connexions in the rat submandibular gnalgion during post-natal development. J Physiol 273:155–177 32. Lledo PM, Saghatelyan A (2005) Integrating new neurons into the adult olfactory bulb: joining the network, life-death decisions, and the effects of sensory experience. Trends Neurosci 28:248–254 33. Lukaszewicz A, Savatier P, Cortay V, Giroud P, Huissoud C, Berland M, Kennedy H, Dehay C (2005) G1 phase regulation, area-specific cell cycle control, and cytoarchitectonics in the primate cortex. Neuron 47:353–364 34. Luzzati F, De Marchis S, Fasolo A, Peretto P (2007) Adult neurogenesis and local neuronal progenitors in the striatum. Neurodegener Dis 4:322–327 35. Ma DK, Kim WR, Ming GL, Song H (2009) Activity-dependent extrinsic regulation of adult olfactory bulb and hippocampal neurogenesis. Ann NY Acad Sci 1170:664–673 36. MacLaren RE, Pearson RA, MacNeil A, Douglas RH, Salt TH, Akimoto M, Swaroop A, Sowden JC, Ali RR (2006) Retinal repair by transplantation of photoreceptor precursors. Nature 444:203–207 37. McConnell SK (1995) Strategies for the generation of neuronal diversity in the central nervous system. J Neurosci 15:6987–6998 38. Ming GL, Song H (2005) Adult neurogenesis in the mammalian central nervous system. Annu Rev Neurosci 28:223–250 39. Muotri A, Gage FH (2006) Generation of neuronal variability and complexity. Nature 441:1087–1093 40. Nudo RJ (2003) Retuning the misfiring brain. Proc Natl Acad Sci USA 100:7425–7427 41. Oboti L, Savalli G, Giachino C, De Marchis S, Panzica GC, Fasolo A, Peretto P (2009) Integration and sensory experience-dependent survival of newly-generated neurons in the accessory olfactory bulb of female mice. Eur J Neurosci 29:679–692 42. Oppenheim RW, Johnson JE (2003) Programmed cell death and neurotrophic factors. In: Squire LR, Bloom FE, McConnell SK, Roberts JL, Spitzer NC, Zigmond MJ (eds) Fundamental neuroscience. Academic, New York//London 43. Pizzorusso T, Medini P, Berardi N, Chierzi S, Fawcett JW, Maffei L (2002) Reactivation of ocular dominance plasticity in the adult visual cortex. Science 298:1187–1189 44. Purves D (1988) Body and brain: a trophic theory of neural connections. Harvard University Press, Cambridge, MA/London 45. Purves D (1994) Neural activity and the growth of the brain. Cambridge University Press, Cambridge 46. Purves D, Lichtman JW (1980) Synapse elimination in the developing nervous system. Science 210:153–157 47. Purves D, Lichtman JW (1985) Principles of neural development. Sinauer, Sunderland 48. Purves D, Snider VD, Voyvodic JT (1988) Trophic regulation of nerve cell morphology and innervation in the autonomic nervous system. Nature 336:123–128 49. Purves D, White LE, Riddle D (1996) Is neural development Darwinian? Trends Neurosci 19:460–464 50. Raisman G, Field PM (1973) A quantitative investigation of the development of collateral reinnervation after partial deafferentation of the septal nuclei. Brain Res 50:241–264

174

F. Rossi

51. Reichert E (2009) Evolutionary conservation of mechanisms for neural regionalization, proliferation and interconnection in brain development. Biol Lett 5:112–116 52. Robel S, Berninger B, G€ otz M (2011) The stem cell potential of glia: lessons from reactive gliosis. Nat Rev Neurosci 12:88–104 53. Rossi F, Gianola S, Corvetti L (2007) Regulation of intrinsic neuronal properties for axon growth and regeneration. Prog Neurobiol 81:1–28 54. Sale A, Berardi N, Maffei L (2009) Enrich the environment to empower the brain. Trends Neurosci 32:233–239 55. Sanes JR, Lichtman JW (1999) Development of the vertebrate neuromuscular junction. Annu Rev Neurosci 22:389–442 56. Schweigreiter R (2008) The natural history of the myelin-derived nerve growth inhibitor Nogo-A. Neuron Glia Biol 4:83–89 57. Striedter GF (2004) Principles of brain evolution. Sinauer, Sunderland 58. Suh H, Weng D, Gage FH (2009) Signaling in adult neurogenesis. Annu Rev Cell Dev Biol 25:153–175 59. Sur M, Frost DO, Hockfield S (1988) Expression of a surface-associated antigen on Y-Cells in the cat lateral geniculate nucleus is regulated by visual experience. J Neurosci 8:874–882 60. Wiesel TN (1982) Postnatal development of the visual cortex and the influence of environment. Nature 299:583–591 61. Williams ME, de Wit J, Ghosh A (2010) Molecular mechanisms of synaptic specificity in developing neural circuits. Neuron 68:9–18 62. Wong ROL, Lichtman JW (2003) Synapse elimination. In: Squire LR, Bloom FE, McConnell SK, Roberts JL, Spitzer NC, Zigmond MJ (eds) Fundamental neuroscience. Academic, New York/London 63. Zheng D, Purves D (1995) Effects of increased neural activity on brain growth. Proc Natl Acad Sci USA 92:1802–1806 64. Zhou X, Merzenich MM (2009) Developmentally degraded cortical temporal processing restored by training. Nat Neurosci 12:26–28 65. Zhou X, Ngarajan N, Mossop BJ, Merzenich MM (2008) Influences of un-modulated acoustic inputs on functional maturation and critical-period plasticity of the primary auditory cortex. Neuroscience 154:390–396 66. Zipursky SL, Sanes JR (2010) Chemoaffinity revisited: dscams, protocadherins, and neural circuit assembly. Cell 143:343–353

Is the Human Brain Unique? Gerhard Roth

Abstract The human brain is not unique in terms of general structure. It exhibits a morphology typical of mammals and more specific of primates. Also, humans do not have the largest brain either in absolute or in relative terms, although they possess a brain that is seven to eight times larger than expected from general mammalian brain-body relationship. The size of the human cerebral cortex and of the prefrontal cortex as the “seat” of intelligence exhibit a slightly positive allometric growth, i.e. the cortex increases faster in size than the rest of the brain, which is again typical of mammals. Due to a relatively thick cortex and a relatively high neuronal packing density, humans have the highest number of cortical neurons (12–15 billions), which is more than the number of cortical neurons found in cetaceans (whales and dolphins) and elephants with much larger brains up to 10 kg. Furthermore, due to a higher axonal conduction velocity and shorter interneuronal distance, humans have a higher cortical information processing capacity than these large-brained mammals. The largest differences between humans on the one hand and all other mammals/vertebrates on the other consist in (1) a strongly increased growth period of the human brain exposing it to a much higher degree to education, and (2) the presence of the Broca speech center which is a necessary prerequisite of syntactical language and developed only recently, i.e., about 100,000 years ago. While these two traits appear to be minor steps in human biological evolution, they had enormous consequences for human culture and intelligence.

Humans are proud of their brain and their cognitive abilities, and many of us including many neuroscientists believe that the alleged uniqueness of human nature is due to the uniqueness of the human brain. In the following, I will briefly discuss

G. Roth (*) Brain Research Institute, Bremen, Germany e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_11, # Springer-Verlag Italia 2012

175

176

G. Roth

some popular claims about the human brain that can be found even in the scientific literature. These claims are (1) The human brain is anatomically unique; (2) Humans have the largest brain in absolute terms; (3) Humans have the largest brain relative to body size; (4) Humans have largest cerebral cortex, particularly prefrontal cortex; (5) Humans have some brain centers or functions not found in other animals. First claim: The human brain is anatomically unique. All tetrapod vertebrates (“land vertebrates”, i.e., amphibians, reptiles, birds, mammals) have brains that – despite enormous differences in outer appearance, overall size and relative size of major parts of the brain – are very similar in their general organization and even in many details [19, 27]. More specifically, all tetrapod brains possess a median, medial and lateral reticular formation inside the medulla oblongata, a pons and ventral mesencephalon, including a noradrenergic locus coeruleus, serotonergic raphe nuclei and a medial ascending reticular activating system. There is a corpus striatum, a globus pallidus, a nucleus accumbens, a substantia nigra, a basal forebrain/septum and an amygdala within the ventral telencephalon, a lateral pallium, homologous to the olfactory cortex of mammals, and a medial pallium, homologous to the hippocampal formation (at least Ammon’s horn and subiculum). This means that all structures required for attention, declarative memory (or its equivalents in animals), emotions, motivation, guidance of voluntary actions and evaluation of actions are present in the non-human tetrapod brain. These structures essentially have the same connectivity and distribution of transmitters, neuromodulators and neuropeptides in the different groups of tetrapods including man. A more difficult problem is the presence of structures homologous to the mammalian isocortex in the telencephalon of other tetrapods. Amphibians possess a dorsal pallium, turtles and diapsid reptiles have a dorsal cortex plus a specific structure called dorsal ventricular ridge (DVR), birds have a hyperpallium and meso-nidopallium, and these structures are believed by many comparative neurobiologists to be homologous to parts of the cortex and not to the basal ganglia of mammals, as previously assumed [15, 17, 20, 23]. However, major differences exist between these structures with regard to cytoarchitecture and size. In amphibians, the dorsal pallium is small and unlaminated; in lizards it is relatively larger, and in turtles and some diapsid reptiles it shows a three-layered structure. In birds, those parts assumed to be homologous to the mammalian cortex (i.e., hyperpallium and meso-nidopallium) are large, but unlaminated. In mammals – with the exception of insectivores and cetaceans – the dorsal pallium or isocortex shows the characteristic six-layered structure. Despite these differences it is safe to assume that the dorsal pallium and cortex of amphibians and reptiles is at least homologous to the limbic and associative cortex of mammals, while a primary sensory and motor cortex appears to be absent. When we compare birds such as pigeons or parrots with roughly equally intelligent mammals such as dogs, then it becomes apparent that the same or very similar cognitive functions are performed by anatomically very different kinds of pallium/cortex (cf. [27, 28]). Second claim: Humans have the largest brain in absolute terms. This is definitely wrong, as can be seen from Fig. 1 and Table 1. Humans have large brains (1.4 kg

Is the Human Brain Unique?

177

Toothed whale

Man

Ape

Dog

Hare

Armadillo

Fig. 1 Series of mammalian brains, all drawn to the same scale. Evidently, man has neither the largest brain nor the most convoluted cortex. Convolution of the cortex as well as of the cerebellum increases monotonically with an increase in brain size

average weight), which is the largest among extant primates (the extinct Homo neandertalensis had a somewhat larger brain), but by far not the largest one among mammals. The largest mammalian brains (and of all animals) are found in elephants (up to 5.7 kg) and whales (up to 10 kg). Third claim: Humans have the largest brain relative to body size. This is wrong, too. While the human brain occupies about 2% of body mass, in very small rodents relative brain size goes up to 10%. However, again among primates, humans have

178

G. Roth

Table 1 List of brain weights in mammals

Brain weight in mammals (g) Sperm whale Elephant Man Horse Gorilla Cow Chimpanzee Lion Dog Cat Rat Mouse

8,500 5,000 1,400 590 550 540 400 220 135 30 2 0.4

Brain weight (g) 10,000

1000

100

10

1

0.1 0.001

0.01

0.1

1

10

100

1000

10,000 100,000 Body weight (kg)

Fig. 2 The relationship between brain size and body size in vertebrates. Double-logarithmic graph. Open circles: bony fishes; open triangles: reptiles; filled triangles: birds; filled circles: mammals except primates; open squares: primates; encircled open squares: Homo sapiens (After Jerison [8])

the largest relative brain size. The relationship between brain size and body size is being discussed for more than 100 years (cf. [8]). It appears that body size is the single most important factor influencing brain size, i.e., large animals generally have large brains in absolute terms. However, increase in brain size does not strictly parallel the increase in body size, but follows only to the power of 0.66 – 0.75 (i.e., 2/3 or 3/4, depending on the statistics used; [9]), – a phenomenon called negative brain allometry [8] (Figs. 2 and 3). Consequently, small animals of a given taxon have relatively larger brains and large animals of this group have relatively smaller brains. Among mammals, this is reflected by the fact that in very small rodents


179

Fig. 3 The relationship between brain size and body size in mammals. Data from 20 mammalian species. Double-logarithmic graph (From Nieuwenhuys et al. [19], modified)

Fig. 4 Brain weight as a percentage of body weight for the same 20 mammalian species as above. Double-logarithmic graph (From Nieuwenhuys et al. [19], modified)

brains occupy up to 10% of body mass, in pigs 0.1% and in the blue whale, the largest living animal less than 0.01% (Fig. 4). In addition, the different groups of vertebrates, while satisfying the principle of negative brain allometry, exhibit considerable differences in their fundamental brain-body relationship (Fig. 5). Among tetrapods, mammals and birds generally

180

G. Roth Brain weight (g) 10,000

Man

1000 Mammals 100 Birds

10

Chondrichthyes

1 Reptiles

0.1 Amphibians

Cyclostomes

0.01 0.001

Osteichthyes 0.001

0.1

10

1000 100,000 Body weight (kg)

Fig. 5 Diagrams showing the relationship between body weight and brain weight in the different classes of vertebrates. Evidently, these classes differ in their general brain weight–body weight relationship, with the cyclostomes having the smallest and mammals having the largest relative brain weights. Remarkably, chondrichthyans (cartilaginous fishes, i.e., sharks and rays) have much larger relative brains than osteichtyans (bony fishes, above all teleosts). Double-logarithmic graph (After Jerison [9], modified)

have larger brains relative to body volume or weight than amphibians and reptiles, and among mammals, primates have relatively larger brains than other orders. Thus, during the evolution of birds and mammals and more specifically of cetaceans and primates, genetic and epigenetic systems controlling brain size have undergone substantial changes in favor of relatively larger brains. These changes resulted in enlargements of brains beyond that associated with body size [9, 11]. Thus, contrary to a common belief, humans do not have the largest brain either in absolute or relative terms. Unless we accept that cetaceans and elephants are more intelligent than humans and/or have states of consciousness not present in humans, the absolute or relative size of the human brain per se cannot account for our factual or alleged superior cognitive abilities. However, among relatively large animals man stands out with a brain that constitutes 2% of body mass. We can quantify this fact by determining the so-called encephalization quotient (EQ) which indicates the ratio between the actual relative brain size of a group of animals to the relative brain size as expected on the basis of brain allometry determined by body size alone (Table 2). Calculating the EQ for the human brain, it turns out that it is more than seven times larger than that of an average mammal and about three times larger than that of a chimpanzee, if they had the size of a human being [8, 9].

Is the Human Brain Unique? Table 2 Encephalization in mammals (After [1, 8, 9])

181

Encephalization quotient in mammals Man Dolphin Chimpanzee Monkey Elephant Whale Marmot Fox Walrus Camel Dog Squirrel Cat Horse Sheep Mouse Rat Rabbit

7.4 5.3 2.5 2.1 1.9 1.8 1.7 1.6 1.2 1.2 1.2 1.1 1.0 0.9 0.8 0.5 0.4 0.4

While man stands out in this respect among primates, similar processes must have taken place among cetaceans. Toothed whales, particularly members of the family Delphinidae, exhibit EQs that are far superior to all primates except Homo sapiens [16]. While man has an EQ of about 7, dolphins have EQs up to 5, and the great apes (except man) have EQs around 2. Thus, humans have a much larger brain than expected among primates, but even in this respect their brain is by no means unique, as the example of dolphins shows. Fourth claim: Humans have the largest cerebral cortex, particularly prefrontal cortex. There are enormous differences both in absolute and relative brain and pallial/cortical size among tetrapods and among mammals in particular. For example, man has a brain and a cortex that are roughly 3,000 times larger in volume than those of a mouse. This implies that changes in relative size of cortex are inconspicuous, because in mammals cortical size rather strictly follows changes in brain size, but, again, there are differences within mammalian groups. Apes (including man) have somewhat larger isocortices than other primates and other mammals, because their forebrains (telencephalon plus diencephalon) are generally somewhat larger constituting 74% of the entire brain as opposed to about 60% in other mammals including mice. At 40% of brain mass the human cortex has the size expected in an ape [9]. The enormous increase in cortical volume is partly the result of an increase in brain volume and consequently in cortical surface (which is related to an increase in brain volume by exactly the power of 2/3; [8]), and partly the result of an increase in the thickness of the cortex. The cortex is about 0.8 mm thick in mice and 2.5–4 mm in man. Remarkably, both cetaceans (whales and dolphins) and elephants have unusually thin cortices with 1.2–1.6 mm.

182

G. Roth

In mammals, the number of neurons per unit cortical volume decreases with an increase in cortical thickness and brain size. According to data from Haug [5], cortical neuronal density (i.e., the number of neurons per cubic millimeter of cortex) amounts to a maximum of 60,000–75,000 in prosimians and monkeys, while with about 25,000, apes and humans have a much lower cortical neuronal density. However, with 6,000–7,000 neurons, whales and elephants exhibit the lowest cortical neuronal density found in mammals. These data clearly contradict the much-cited claim of Rockel and co-workers [25] that in all mammals a standard vertical cortical column contains the same number of neurons independent of total cortical volume. After Haug such a column contains 190,000 in monkey, and 50,000 (varying between 30,000 and 100,000 across different cortical areas) in humans and only 19,000 in elephants and whales and dolphins. This decrease in the number of cortical neurons per unit volume is a consequence of a roughly equal increase in the length of axonal and dendritic appendages of neurons, in the number of glial cells and in the number of small blood vessels. Without such an increase in glial cells and blood vessels, large isocortices would probably be both architecturally and metabolically impossible. We recognize that the dramatic decrease in nerve cell packing density is only partly compensated for by an increase in cortical thickness. Knowing cortical volume or surface, we can calculate the total number of cortical neurons in mammals [28]. As shown in Table 3, humans with 12–15 billion neurons (depending on cell density estimates) have the highest number of cortical neurons, because their cortex is relatively thick and has a medium neuronal density despite the fact that their cortex is by far not the largest one. Humans are closely followed by whales and elephants; they have much larger cortices, but these are much thinner, and the neuronal packing density is much lower. In addition, the cortex of whales and dolphins shows a different cytoarchitecture, e.g., lacking a distinct cortical layer IV. This is considered by experts due to secondary loss, Table 3 Number of cortical neurons in mammals (From [28]

Number of neurons in the cortex of mammals (from Roth and Dicke, 2005) Species Man Elephant Whale Chimpanzee Dolphin Rhesus monkey Cat Dog Opossum Hedgehog Rat Mouse

No. cortical neurons (millions) 12–15,000 11,000 10,500 6,200 5,800 480 300 160 27 24 15 4


183

because the ungulate ancestors of cetaceans presumably had a normal six-layered cortex. In addition to a much higher neuronal density, the human cortex, when compared with that of the large-brained cetaceans, exhibits a much higher axonal conduction velocity, which is due to a much thicker myelin sheath of cortical axons [2, 3, 26, 30]. In combination with a shorter distance between pyramidal cells this suggests that primates including humans possess a much faster velocity of information processing than cetaceans. Recently, Kaas [13, 14] argued that the number of cortical areas increased dramatically from about 20 such areas in the hypothetical insectivore-like ancestor to more than 60 in primates. However, what has increased – according to Kaas – was the number of functionally intermediate areas, but neither the primary nor the highly associative areas. Kaas is right to warn about the danger of greatly underestimating the number of functionally different cortical areas in small-brained mammals. Available data suggest that – contrary to common belief – the associative cortex has increased roughly in proportion to an increase in brain and cortical size. This apparently is the case for the prefrontal cortex, which is regarded by many neuroscientists and neurophilosophers as the true seat of consciousness. Anatomically, the prefrontal cortex is defined as the cortical area with major (though not exclusive) input from the mediodorsal thalamic nucleus [24, 29]. Using this definition, it turns out that the PFC has increased with an increase in cortical and overall brain volume within groups of mammals, but here again we find an additional increase in relative PFC size with an increase in absolute brain size across mammalian orders: in rats, PFC constitutes 6.5%, in dogs, 8.7%, in cows 9.8% and in man 10.6% of brain mass [10]. What follows is that the human PFC has exactly the size expected according to primate brain allometry. Of course, cetaceans as well as elephants have prefrontal cortices which are much larger in absolute terms than the human PFC, but what they do with this massive “highest” brain center, remains a mystery so far. Fifth claim: Humans have unique cortical structures and functions. We have not yet found anything in brain anatomy that would explain the factual or alleged uniqueness of the human brain and of humans regarding cognition and consciousness. Given the fact that Homo sapiens has an absolutely and relatively large brain and cortex, it appears to be the animal with the highest number of cortical neurons and/or synapses. Remarkable, however, is the strong increase in relative (and absolute) brain size in hominid evolution during the last 3–4 million years. While in the Great apes as well as in the australopithecines that did not belong to our ancestors, brain size increases with body size to a power of 0.33, in the hominin lineage leading to Homo sapiens it increased to a power of 1.73, i.e. in a positively allometric fashion, which means that brain size increased faster than body size (Fig. 6). However, the reasons for this phenomenon are completely unclear. What remains is the question whether there are any anatomical or physiological specializations in the human cortex that could be correlated with the unique cognitive abilities attributed to man. As to the general cytoarchitecture of the

184

G. Roth

Hominins Homo sapiens

1250

Homo erectus

1.7 3 e= Slo p

Log endocranial volume (cm3)

1000

750

Homo habilis

Australopithecines 33

0. pe =

Slo

Australopithecus boisei Australopithecus robustus 34 = 0. ope l S Australopithecus africanus

500

Gorilla

Great apes Orangutan Chimpanzee 350 Bonobo 30

40

50 Log body weight (kg)

75

100

Fig. 6 Increase in endocranial volume in the Great apes, Australopithecines and in Hominids. Double-logarithmic graph (After Pilbeam and Gould [21], modified)

human cortex, it is indistinguishable from that of other primates and most other mammals. Likewise, no differences have been discovered so far between humans and non-human mammals with respect to short-term or long-term plasticity of cortical neurons, the action of neuromodulators etc. Only two traits have been discovered that could drastically distinguish the human cortex from that of other primates, viz., (1) differences in growth rate and length of growth period and (2) the presence of the Broca speech center. As to (1), maturation of the brain is more or less completed at 2 years after birth in prosimians and 6–7 years in monkeys and non-human apes, but the human brain still continues to mature until the age of 20, which is much longer than in any other primate [7, 21]. A critical phase in the development of the human brain seems to occur around the age of 2.5 years. At this time, major anatomical rearrangements in the associative cortex have come to a stop, and the period of fine-wiring appears to start, particularly in layer 3 of the prefrontal cortex [18]. As mentioned above, at this time, human children “take off” cognitively compared to non-human primates.


185

Without any doubt, the drastically prolonged period of brain development constitutes one important basis for an increased capability of learning and memory formation. The other trait concerns the presence of the Broca speech center in the frontal lobe responsible for temporal aspects of language including syntax, along with the Wernicke speech center in the temporal lobe which is responsible for the meaning of words and sentences (while meaning is likewise dependent on syntax and grammar). It is to date unclear whether these speech centers are true evolutionary novelties. All mammals studied so far have a center for intraspecific communication within the temporal lobe (mostly left side) which may be homologous to the Wernicke center for semantics. It has been reported that destruction of these areas leads to deficits in intraspecific vocal communication [6]. In addition, it has long been argued that the posterior part (A 44) of the Broca speech center in humans and the ventral premotor area of non-human primates probably are homologous [22]. The ventral premotor area controls the movement of forelimbs, face and mouth, which is likewise the case for the posterior portion of the Broca area. According to a number of primatologists, non-human primates lack a direct connection between the motor cortex and the nucleus ambiguous, where the laryngeal motor neurons are situated. In man, bilateral destruction of the facial motor cortex abolishes the capacity to produce learned vocalization including speech or humming a melody, while a similar destruction in monkeys has no such consequences [12]. According to a number of experts, the evolutionary basis for human language was an emotionally driven stereotyped language typical of non-human primates. During hominin evolution, the cortex gained control over this system such that beyond the initiation of hard-wired, innate sounds a flexible production of sounds and their sequences became possible [4, 12]. Such an interpretation, however, contrasts with evidence of a high degree of sound learning in monkeys [31] and the mentioned consequences of destruction of left-hemispheric, Wernicke-like temporal areas in all mammals. Non-human primates including the great apes are strongly limited even in nonvocal speech based on the use of sign language or symbols, and these limitations seem to concern mostly syntax. Accordingly, anything concerning language in the human brain developed relatively recently or underwent substantial modifications, and it was probably the Broca center rather than the Wernicke center. Such an assumption is consistent with the fact that the most clear-cut differences between humans and non-human primates concern syntactical complexity of language. Thus, during hominin evolution a reorganization of the frontal-prefrontal cortex appears to have taken place such that the facial and oral motor cortices and the related subcortical speech centers came under the control of a kind of cortex that is specialized in all aspects of temporal sequence of events including the sequence of action [4]. This evolutionary process appears to have taken place relatively recently, i.e. 100,000–80,000 years ago.

186

G. Roth

Conclusions It turns out that the human brain is not unique in terms of general structure; rather, it exhibits the bauplan typical of mammals and more specific of primates. Also, humans do not have the largest brain either in absolute or in relative terms, although they possess a brain that is 7–8 times larger than expected from general mammalian brain allometry. The size of the human cerebral cortex and of the prefrontal cortex exhibit a slightly positive allometric growth, which is again typical of mammals. However, due to a relatively thick cortex and a medium neuronal packing density found in hominids, humans have the highest number of cortical neurons (about 12 billions) found mammals (and animals), which, however, is only slightly above the numbers found in cetateans and elephants. The fact that axonal conduction velocity and neuronal packing density is much higher in humans compared to these largebrained mammals, this may lead to a much faster cortical information processing as a basis for human intelligence [27]. The greatest differences between humans on the one hand and all other mammals/vertebrates on the other consist in (1) a strongly increased growth period of the human brain exposing it to a much higher degree to education, and (2) the presence of the Broca speech center which is a necessary prerequisite of syntactical language. While these two traits appear to be minor steps in human biological evolution, they had enormous consequences for human culture.

References 1. Blinkov SM, Glezer II (1968) The central nervous system in figures and tables. VEB FischerVerlag, Jena 2. Changizi MA (2001) Principles underlying mammalian neocortical scaling. Biol Cybern 84:207–215 3. Changizi MA (2007) Scaling the brain and its connections. In: Kaas JH, Krubitzer LA (eds) Evolution of nervous systems. A comprehensive review. Vol 3: Mammals. Academic Press (Elsevier), Amsterdam/Oxford, pp 167–180 4. Deacon TW (1990) Rethinking mammalian brain evolution. Am Zool 30:629–705 5. Haug H (1987) Brain sizes, surfaces, and neuronal sizes of the cortex cerebri: a stereological investigation of man and his variability and a comparison with some mammals (primates, whales, marsupials, insectivores, and one elephant). Am J Anat 180:126–142 6. Heffner HE, Heffner RS (1995) Role of auditory cortex in the perception of vocalization by Japanese Macaques. In: Zimmermann E, Newman JD, J€urgens U (eds) Current topics in primate vocal communication. Plenum, New York/London, pp 207–219 7. Hofman MA (2000) Evolution and complexity of the human brain: some organizing principles. In: Roth G, Wullimann MF (eds) Brain evolution and cognition. Wiley-Spektrum Akademischer Verlag, New York/Heidelberg, pp 501–521 8. Jerison HJ (1973) Evolution of the brain and intelligence. Academic, New York 9. Jerison HJ (1991) Brain size and the evolution of mind. American Museum of Natural History, New York


187

10. Jerison HJ (1997) Evolution of prefrontal cortex. In: Krasnegor NA, Lyon GR, GoldmanRakic PS (eds) Development of the prefrontal cortex: evolution, neurobiology, and behavior. Brookes Publishing, Baltimore/London/Toronto/Sydney, pp 9–26 11. Jerison HJ (2000) The evolution of neuronal and behavioral complexity. In: Roth G, Wullimann MF (eds) Brain evolution and cognition. Wiley-Spektrum Akademischer Verlag, New York/Heidelberg, pp 523–553 12. J€urgens U (1995) Neuronal control of vocal production in non-human and human primates. In: Zimmermann E, Newman JD, J€ urgens U (eds) Current topics in primate vocal communication. Plenum, New York/London, pp 199–206 13. Kaas JH (1995) The evolution of isocortex. Brain Behav Evol 46:187–196 14. Kaas JH (2007) Reconstructing the organization of neocortex of the first mammals and subsequent modifications. In: Kaas JH, Krubitzer LA (eds) Evolution of nervous systems. A comprehensive review. Vol 3: Mammals. Academic Press (Elsevier), Amsterdam/Oxford, pp 27–48 15. Karten HJ (1991) Homology and evolutionary origins of the “neocortex”. Brain Behav Evol 38:264–272 16. Marino L (1998) A comparison of encephalization between odontocete cetaceans and anthropoid primates. Brain Behav Evol 51:230–238 17. Medina L (2007) Do birds and reptiles possess homologues of mammalian visual, somatosensory, and motor cortices. In: Kaas J, Bullock TH (eds) Evolution of nervous systems. A comprehensive review. Vol 2: Non-mammalian vertebrates. Academic Press (Elsevier), Amsterdam/Oxford, pp 163–194 18. Mrzljak L, Uylings HBM, van Eden CG, Juda´s M (1990) Neuronal development in human prefrontal cortex in prenatal and postnatal stages. In: Uylings HBM, van Eden CG, de Bruin JPC, Corner MA, Feenstra MGP (eds) The prefrontal cortex. Its structure, function and pathology. Elsevier, Amsterdam/New York/Oxford, pp 185–222 19. Nieuwenhuys R, ten Donkelaar HJ, Nicholson C (1998) The central nervous system of vertebrates, vol 3. Springer, Berlin 20. Northcutt RG, Kaas JH (1995) The emergence and evolution of mammalian isocortex. Trends Neurosci 18:373–379 21. Pilbeam D, Gould SJ (1974) Size and scaling in human evolution. Science 186:892–901 22. Preuss TM (1995) Do rats have a prefrontal cortex? The Rose-Woolsey-Akert program reconsidered. J Cogn Neurosci 7:1–24 23. Reiner A, Yamamoto K, Karten HJ (2005) Organization and evolution of the avian forebrain. Anat Rec A 287A:1080–1102 24. Roberts AC, Robbins TW, Weiskrantz L (1998) The prefrontal cortex. Executive and cognitive functions. Oxford University Press, Oxford/New York/Tokyo 25. Rockel AJ, Hiorns W, Powell TPS (1980) The basic uniformity in structure of the neocortex. Brain 103:221–244 26. Rockland KS (2002) Non-uniformity of extrinsic connections and columnar organization. J Neurocytol 31:247–253 27. Roth G (2010) Wie einzigartig ist der Mensch? Die lange Evolution der Gehirne und des Geistes. Spektrum, Heidelberg 28. Roth G, Dicke U (2005) Evolution of the brain and intelligence. Trends Cogn Sci 9:250–257 29. Uylings HBM, van Eden CG (1990) Qualitative and quantitative comparison of the prefrontal cortex in rat and in primates, including humans. In: Uylings HBM, van Eden CG, de Bruin JPC, Corner MA, Feenstra MGP (eds) The prefrontal cortex. Its structure, function and pathology. Elsevier, Amsterdam/New York/Oxford, pp 31–62 30. Zhang K, Sejnowski TJ (2000) A universal scaling law between gray matter and white matter of cerebral cortex. Proc Natl Acad Sci USA 97:5621–5626 31. Zimmermann E (1995) Loud calls in nocturnal prosimians: structure, evolution and ontogeny. In: Zimmermann E, Newman JD, J€ urgens U (eds) Current topics in primate vocal communication. Plenum, New York/London, pp 47–72

.

Aristotle and the Chicken: Animacy and the Origins of Beliefs Giorgio Vallortigara

Abstract Mechanisms seem to be available at birth in the vertebrate brains to distinguish the domain of inanimate objects (for inferring physical causality) and the domain of animated objects (for inferring social causality). These include responses to biological motion, self-propelled motion and face-like stimuli in animals so different as newly-hatched domestic chicks and human newborns. Detecting the presence and understanding the intentions of other agents is crucial in order to survive and reproduce. Mechanisms to detect animacy (and agency) have been argued to underwent a sort of hypertrophic development in our species, likely because of the demands and the consequent complexities of our social life. There has been a long road from the primitive animacy detectors that we can see operating even in simple brains to the intricacies of agency attribution and theory of mind of human beings. Nonetheless, the origins of beliefs in supernatural things seem to be deeply rooted in the natural history of animacy detection.

1 A Perceptual “Life Detector” in the Brain? In The Descent of Man (Chap. 3) Darwin [17] wrote: The tendency in savages to imagine that natural objects and agencies are animated by spiritual or living essences, is perhaps illustrated by a little fact which I once noticed: my dog, a full-grown and very sensible animal, was lying on the lawn during a hot and still day; but at a little distance a slight breeze occasionally moved an open parasol (. . .) every time that the parasol slightly moved, the dog growled fiercely and barked. He must, I think, have reasoned to himself in a rapid and unconscious manner, that movement without any apparent cause indicated the presence of some strange living agent.

G. Vallortigara (*) Faculty of Cognitive Sciences, Director of the Animal Cognition and Neuroscience Lab (CIMeC), University of Trento, Trento, Italy e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_12, # Springer-Verlag Italia 2012

189

190

G. Vallortigara

Research in modern cognitive neuroscience picked up Darwin’s implicit suggestion that there maybe primitive neural pathways that ensure a bias to attend toward or preferentially process, sensory cues about other living things [13, 30] – and in particular members of the same species. I became interested in what has been called the perceptual life detector in the brain [24] in an indirect way. While studying filial imprinting in domestic chicks – the process by which the young of some precocial species learn to recognize an object, usually the mother hen and siblings, by simply being exposed to it for a short period of time during a critical period soon after hatching [6, 21] – I became curious about the role of motion in the imprinting process. Ethology textbooks state that imprinting is more likely to be obtained and more strong using motion rather than stationary stimuli. I wondered, however, whether any type of motion would be identically effective or whether animals would be in some ways “prepared” to be sensitive to certain types of movement. The broody hen shows a very peculiar pattern of movement and I decided to check whether, before any imprinting has occurred, newly-hatched chicks would show a tendency to selectively approach such a type of motion. To this aim, together with my collaborators, I take advantage of point-light displays [23] that prevent use of two-dimensional information about the shape. An example is shown in Fig. 1. The picture is obtained by locating 13 point of lights on the joints of a digitalized image of a moving hen. When a single motionless frame is observed it is difficult to extract any structure from this very impoverished stimulus. However, when point of lights are set into motion the shape of the animal and the type of action it is involved in become effortlessly and immediately available to human observers. When we tested chicks using these stimuli, however, it turned out that my initial conjecture was wrong [41]. Newly-hatched, completely visually naı¨ve chicks did indeed show a preference but it was not specific of their own species. Faced with a

Fig. 1 A newly hatched chick confronted with a point-light display of a moving hen (see text for details)

Aristotle and the Chicken: Animacy and the Origins of Beliefs

191

choice between point-light displays depicting a moving hen versus random motion or rigid motion (the latter obtained by rotating around the vertical axis a single frame of points of light of the moving hen) chicks showed a preference for the moving hen. However, when presented with a scrambled hen, in which points of light were spatially dislocated at random, though retaining their local motion signals, the walking hen was chosen as much as the scrambled hen; though both the walking hen and the scrambled hen were preferred to the rigid and random motion. This finding suggests that chicks preferentially approach semi-rigid motion, the type of motion which is exhibited by vertebrate animals. In semi-rigid motion some points maintain a fixed distance from each other (e.g., two points placed close on the same limb) but can nonetheless vary their distance with respect to other points (e.g. with respect to points located on the torso). Such a pattern of semi-rigid motion is shared by the walking and the scrambled hen, even though the latter does not match any existing biological creature. As a control for this hypothesis we used the motion of a point-light cat, a species that can predate on young chicks. As predicted, chicks did not exhibit any preference between the walking hen and the walking cat point-light sequence, though they did prefer the walking cat to the random and to the rigid motion point-light sequence.

2 Of Chicks and Faces The predisposition found for certain kinds of movements shares characteristics in common with those earlier demonstrated for the head and neck region of a hen to artificial objects [25]. In 1988 neurobiologist Gabriel Horn in Cambridge, and, at for a time, his graduate student Mark Johnson, carried out some groundbreaking studies showing that, contrary to widely held beliefs, filial imprinting seems to consist of two separate processes: an inborn predisposition of the young bird to attend to visual stimuli that resemble a broody hen, and a learning mechanism (which would be guided and supported by the innate predisposition) to learn by exposition about the specific, unique characteristic of a particular mother hen [25]. Subsequently, Johnson moved to studies on human infant face preferences and together with John Morton published a series of seminal papers (see for a review [26]) arguing that a similar two-mechanism device would be available to human neonates for face recognition. According to their model, infants are born with some information about the structure of faces. This structural information, termed Conspec, guides the preference for facelike patterns found in newborn infants. Conspec is contrasted with a device termed Conlern, which is responsible for learning about the visual characteristics of conspecifics. Subsequent work, however, has cast some doubt as to the precise nature of the Conspec mechanism, in particular it has been argued that contrary to Morton and Johnson’s theory, newborn infants’ preferences for faces would be a secondary effect determined by non-specific biases due to constraints imposed by the immature visual system of the child. In particular, Turati et al. [39] provided evidence that the preference for face-like stimuli would be determined by an “Up-Down

192

G. Vallortigara

bias” that would direct baby’s attention toward any configuration presenting more elements in the upper part (a “top-heavy configuration”). However, differently from chicks, human newborns cannot be completely prevented from being exposed to faces. Thus, it is unclear as to whether part of the controversy would depend on an effect of early learning. We have recently reconsidered the issue and our results suggest that chicks have indeed an inborn preference to approach face-like stimuli, resembling their head region (e.g., they preferred the stimulus on the left in the pairs of pictures shown in Fig. 2; [33].). We also showed that both newly hatched chicks and human newborns demonstrate similar preferences for face stimuli over spatial frequency matched structured noise ([32]; see Fig. 3), providing strong converging evidence that vertebrates have a domain-relevant bias toward faces shortly after hatching or birth. Similarly to the preference for biological movement, the preferences for faces is not species-specific (chicks, for instance, respond to face-like characteristics of a predator like a polecat; [25]).

Fig. 2 Schematic face-like stimuli used for experiments with visually-inexperienced chicks (see text for details)

Fig. 3 Example of the face (left) and noise (right) stimuli used in the study comparing human newborns and chicks preferences (see text for details)


193

When considered together, these findings seem to fit a general scheme for cognitive development of recognition of other animals based on the interaction between two separate and independent systems. The first of these systems would direct the attention of the young animal toward the appropriate class of objects to learn about, in the absence of any prior specific experience (e.g., in the case of motion those objects that move semi-rigidly). The second system would be concerned with learning about the peculiar characteristics of the objects to which attention has been directed by the first system. Given that in a natural environment it is more likely that the newly-hatched chick would encounter a mother hen rather than a cat, a developing predisposition to pay attention to objects showing the characteristic motion of vertebrates would assure the highest probability to learn (by way of the imprinting mechanism) about the specific pattern of motion of the mother-hen. Could these findings relative to biological motion be generalized to the human species as well? The answer seems to be positive. An inborn predisposition to attend to biological motion has long been theorized for the human species, but had so far not been demonstrated. In particular, no preference for biological motion was reported for human infants of less than 3 months of age [18]. Recently, however, Simion et al. [34] tested 2-day-old babies’ discrimination after familiarization and their spontaneous preferences for biological vs. nonbiological point-light animations, using the same type of stimuli (i.e. walking hens) used in our research with newly-hatched chicks. Newborns were shown to be able to discriminate between the two different patterns of motion and, when first exposed to them, selectively preferred to look at the biological motion display. This preference was also orientation-dependent: newborns looked longer at upright displays than upside-down displays (the same result was previously reported for newly-hatched visually naı¨ve chicks, [40]). Overall, these parallel results in the two species strikingly support the hypothesis that detection of biological motion is an intrinsic capacity of the vertebrate visual system, which is presumably part of an evolutionarily ancient and non-species-specific system predisposing animals to preferentially attend to other animals.

3 Aristotle and the Chicken Recent research on human infants has provided important evidence for early sensitivity to causal agency (animacy) and intention (for a review see Biro et al. [8]). I wanted to investigate whether evidence for an inborn preference for objects conveying an impression of causal agency or intention could be observed in inexperienced animals. In the Physics Aristotle wrote: Of the proper subjects of motion some are moved by themselves and others by something not themselves, and some have a movement natural to themselves and others have a movement forced upon them which is not natural to them. Thus the self-moved has a natural motion. Take, for instance, any animal: the animal moves itself, and we call every movement natural, the principle of which is internal to the body in motion. ( vol. V, p. 307) [1]

194

G. Vallortigara

Now, let us suppose to present newly-hatched chicks with a video showing two objects, of different colours (Fig. 4a), on a stage, initially shown at rest. Then one object is shown to move slowly until contact with the other object, thus producing (to a human observer at least) the classical Michotte’s [29] launching effect (see [31] for evidence that non-human animals are also sensitive to Michotte’s perceived causality). The second object would thus move along a straight trajectory for the same length as the previous one, stopping before exiting from the stage. After this exposure phase, chicks would be tested in a free-choice task for spontaneous preference for the two different objects. Complete balancing for use of different colours and left-right direction of movement would be ensured during exposure and at test. If chicks do attribute a notion of animacy to the object that starts moving and contacts the other object, then a preference for such an object would be observed in free-choice preference tests, irrespective of its colour and direction of movement. When tested for their preferences for objects A and B (see Fig. 4b leftmost picture), we found that chicks showed indeed a preference for object A, the self-propelled object playing the “agentive” role during the exposure phase [28]. In order to check whether the perceived causality was crucial, we ran another experiment in which the order of the displacements was swapped temporally: thus object B moved first and object A started its movement only after object B had stopped (Fig. 4b centre picture). In this animation sequence any physical causality between the movements of the two objects would be disrupted (no contact between A and B), whereas distances travelled and perceptual features of the two objects would be identical to those of the launching effect. Both objects would thus appear to be self-propelled. At test, we found no significant preference for either object, showing that the results of the first experiment could not, therefore, be due to a preference for the stimulus that moved first in the animation, since no preference for stimulus B (which moved first) was apparent in this case. However, given that in the latter experiment any physical contact was removed, it was necessary to check whether chicks’ preferences in the first experiment could be accounted for in terms of which object applied physical contact over the other object, which perhaps may have acted as a cue of “agency”. To determine this, chicks were imprinted onto a non-causal physical animation. The stimulus sequence was identical to the launching effect used in the first experiment except for the presence of a 3 s-delay between the time of contact and the motion of B. In human subjects, the presence of such a delay is known to abolish any impression of physical causality: object B would appear in this case as being self-propelled as was object A. We found that chicks similarly showed in this case no preference for either stimulus. It remained unclear, however, whether the choice shown by chicks in the first experiment was due to a preference for the self-propelled stimulus or to a preference for the object which was the “cause” of the motion sequence. To determine this, we exposed chicks to a video animation identical to the one used in the first experiment except for the presence of two opaque screens, one of which occluded


195

Fig. 4 (a) A chick underwent presentation of the launching effect (see text) (b) Schematic representation of the animation sequences used during exposure. In Experiment 1 (left-most sequence), the classical launching effect is reproduced: To humans the sequence appears as object A being a “self-propelled” agent hitting object B and causing its movement. In Experiment 2 (central sequence) the order of movement was swapped: The sequence should appear as the independent motion of two objects, both self-propelled. In Experiment 3 (not shown) chicks were imprinted onto a sequence identical to that used in Experiment 1 except for the presence of a 3 sdelay between the objects contacting one another and the start of motion of object B, which would abolish any impression of physical causality. In Experiment 4 (right-most sequence) no cues were available as to the nature of motion of object A because of the presence of occluding screens, though the causality of the launching effect would be preserved

the object at the beginning and one at the end of the motion sequence (see Fig. 4b rightmost picture). In this way no cues was available about the self/not-self propelled nature of object A, although it continued to be perceivable as the cause

196

G. Vallortigara

of motion of object B. We found that chicks did not show any significant preference for either object. The results of our experiments are thus consistent with Aristotle’s hypothesis: only when one of the two objects appeared as being self-propelled and the other did not, did a preference emerge, as a choice for the self-propelled stimulus. Detection of self-propelled motion is likely to be part of a primitive neural pathway that ensures a bias to attend toward, or preferentially process, sensory information about other living entities, using sensory cues of animacy.

4 From Intuitive Psychology to Intuitive Physics Evidence has been collected suggesting that human infants are born with a conception of objects as spatially bounded entities that exist continuously in time and move continuously in space, maintaining their internal unity and their external boundaries [14, 36, 37]. This is not limited to the human species, however. Other organisms as well seem to possess the rudiments of what has been dubbed “intuitive” (or “naı¨ve”) physics. For instance, similar to human infants [3, 4, 14, 15, 35, 36], non-human primates [12] and dogs [27] represent physical objects and reason about the motion of physical objects in accordance with the basic constraint of solidity of material bodies. Also, rooks [7] and chimpanzees [11] appear to understand the basic rule that contact is required for support, suggesting that they have some understanding of the fact that the physical world is governed by unobservable forces such as gravity. In seminal experiments by Baillargeon et al. [4] 3.5-month old infants habituated to a opaque screen that rotated 180 , upwards and then 180 downwards from a horizontal surface. When subsequently shown an object which was occluded as the screen rotated upward, infants showed surprise at the sight of the impossible event in which the screen continued to rotate the full 180 (as during habituation) despite the apparent presence of the object, whereas they were not surprised when the screen stopped at the angle where it met the object. This suggests that 3.5- month old infants form representations of hidden objects and make the inference that a solid object cannot move through the space occupied by another solid object. But of course such a knowledge about the properties of physical object may be the outcome of observing the behaviour of the objects or of acting upon them. Alternatively, it could be that basic concepts of intuitive physics are present at birth and do not require specific experiences with objects. Recently, we investigate this issue using our animal model Chiandetti and Vallortigara [16]. Chicks were reared singly with a small object that became their social partner. They were then accustomed to rejoin such an imprinting object when it was made to move and disappear behind either one of two identical opaque screens. At test, after disappearance of the imprinting object, chicks were faced with two screens of different slants which could or could not, be compatible with the presence of the imprinting object hidden beneath them. Chicks consistently chose the screen of slant compatible with the


197

presence of the object beneath it. When chicks were imprinted on an object of a smaller size, which could be occluded beneath the screen closest to the horizontal surface, no preference for either screen was observed. Preventing chicks from touching and pecking at the imprinting object before testing did not affect the results, suggesting that the physical constraint according to which a solid object cannot occupy the space of another solid object is a biological predisposition of their brains.

5 Animacy Detection and Origins of Beliefs Several authors (e.g. [2, 5, 9, 10, 20]) have pointed out the implications for our species of the clear-cut divide that our brains operates between the domain of inanimate objects (for inferring physical causality) and that of animated objects (for inferring social causality). In particular the fact that the mechanisms to detect animacy (and agency) underwent a sort of hypertrophic development in our species [10], likely because of the demands and the consequent complexities of our social life [22]. We may appeal to natural causes in order to account for an event. Why did that apple fall from the tree? Because the wind shook the branch of the tree, causing the apple to fall. Alternatively, we may explain phenomena by appealing to agents, entities who act on the basis of their beliefs and desires. Why did the apple fall from the tree? Because Mary shook the tree, causing the apple to fall down, because she wanted to eat the apple. We evolved in an environment containing many agents – prey, predators, conspecific friends and rivals, potential mates and so on. Detecting the presence and understanding the intentions of other agents is crucial to members of our species, in order to survive and reproduce. Thus we evolved to be very sensitive to signals of animacy and agentivity – overly sensitive in fact. As stressed by Barrett [5] humans evolved to have (or, perhaps more plausibly, to be) hyper-active agency detectors. Hyper-active agency detectors would explain the human tendency to believe in the existence of invisible agents, such as spirits, ghosts, angels or gods. As put forwards by Bloom [9], if body and souls are thought of as separate, there can be bodies without souls (stones, tables, corpse, zombies) and souls without bodies (angels, ghosts, demons), opening the possibility to the belief that we ourselves can survive the death of our bodies. There has been of course a long road from the primitive animacy detectors that we can see operating even in simple brains to the intricacies of agency attribution and theory of mind of human beings. Nonetheless, the origins of beliefs in supernatural things [19, 20, 38] and of our intuitive dualism [9] seem to be deeply rooted in natural history.

198

G. Vallortigara

References 1. Aristotle (1980) The physics (trans: Wickstead PH, Cornford FM). Harvard University Press, Cambridge, MA. 2. Atran S (2002) In gods we trust. The evolutionary landscape of religion. Oxford University Press, Oxford 3. Baillargeon R (1995) Physical reasoning in infancy. In: Gazzaniga MS (ed) The cognitive neurosciences. MIT Press, Cambridge, MA, pp 181–204 4. Baillargeon R, Spelke ES, Wasserman S (1985) Object permanence in five-month-old infants. Cognition 20:191–208 5. Barrett JL (2004) Why would anyone believe in god? Rowman Altamira, Lanham 6. Bateson PPG (2000) What must be known in order to understand imprinting? In: Heyes C, Huber L (eds) The evolution of cognition. MIT Press, Cambridge, MA, pp 85–102 7. Bird CD, Emery NJ (2010) Rooks perceive support relations similar to six-month-old babies. Proc Biol Sci 277:147–151 8. Biro S, Csibra G, Gergely G (2007) The role of behavioral cues in understanding goal-directed actions in infancy. Prog Brain Res 164:303–322 9. Bloom P (2004) Descartes’ baby: how the science of child development explains what makes us human. Basic Books, New York 10. Boyer P (2001) Religion explained. Basic books, New York 11. Cacchione T, Krist H (2004) Recognizing impossibile object relations: intuitions about support in chimpanzees. J Comp Psychol 118:140–148 12. Call J (2007) Apes know that hidden objects can affect the orientation of other objects. Cognition 105:1–25 13. Caramazza A, Shelton JR (1998) Domain-specific knowledge systems in the brain: the animate-inanimate distinction. J Cogn Neurosci 10:1–34 14. Carey S (2009) The origin of concepts. Oxford University Press, New York 15. Carey S, Spelke ES (1996) Science and core knowledge. Philos Sci 63:515–533 16. Chiandetti C, Vallortigara G (2011) Intuitive physical reasoning about occluded objects by inexperienced chicks. Proceedings of the Royal Society of London B 278:2621–2627 17. Darwin C (1874/1913) The descent of man, and selection in relation to sex, 2nd edn. D. Appleton & Company, New York 18. Fox R, McDaniel C (1982) The perception of biological motion by human infants. Science 218:486–487 19. Girotto V, Pievani T, Vallortigara G (2008) Nati per credere. Codice Edizioni, Torino 20. Hood BM (2009) SuperSense: why we believe in the unbelievable. HarperOne, London 21. Horn G (2004) Pathways of the past: the imprint of memory. Nat Neurosci 5:108–120 22. Humphrey N (1984) Consciousness regained. Oxford University Press, Oxford 23. Johansson G (1973) Visual perception of biological motion and a model for its analysis. Percept Psychophys 14:201–211 24. Johnson MH (2006) Biological motion: a perceptual life detector? Curr Biol 16:R376–R377 25. Johnson MH, Horn G (1988) Development of filial preferences in dark-reared chicks. Anim Behav 36:675–683 26. Johnson MH, Morton J (1991) Biology and cognitive development. The case of face recognition. Blackwell, Oxford 27. Kundey SMA, Andres De Los Reyes A, Taglang C, Baruch A, German R (2010) Domesticated dogs’ (Canis familiaris) use of the solidity principle. Anim Cogn 13:497–505. doi:10.1007/ s10071-009-0300-6 28. Mascalzoni E, Regolin L, Vallortigara G (2010) Innate sensitivity for self-propelled causal agency in newly hatched chicks. Proc Natl Acad Sci USA 107:4483–4485 29. Michotte A (1963) The perception of causality. Basic Books, New York 30. New J, Cosmides L, Tooby J (2007) Category-specific attention for animals reflects ancestral priorities, not expertise. Proc Natl Acad Sci USA 104:16598–16603


199

31. O’Connell S, Dunbar R-I-M (2005) The perception of causality in chimpanzees (Pan spp.). Anim Cogn 8:60–66 32. Rosa Salva O, Farroni T, Regolin L, Vallortigara G, Johnson MH (2011) The evolution of social orienting: evidence from chicks (Gallus gallus) and human newborns. PLoS ONE 6(4): e18802 33. Rosa Salva O, Regolin L, Vallortigara G (2010) Faces are special for chicks: evidence for inborn domain-specific mechanisms underlying spontaneous preferences for face-like stimuli. Dev Sci 13:565–577 34. Simion F, Regolin L, Bulf H (2008) A predisposition for biological motion in the newborn baby. Proc Natl Acad Sci USA 105:809–813 35. Spelke ES (2000) Core knowledge. Am Psychol 55:1233–1243 36. Spelke ES (2004) Initial knowledge: six suggestions. Cognition 50:431–445 37. Spelke ES, Kinzler KD (2007) Core knowledge. Dev Sci 10:89–96 38. Sperber D (1996) Explaining culture: a naturalistic approach. Blackwell, Oxford 39. Turati C, Simion F, Milani I, Umilta` C (2002) Newborns’ preference for faces: what is crucial? Dev Psychol 38:875–882 40. Vallortigara G, Regolin L (2006) Gravity bias in the interpretation of biological motion by inexperienced chicks. Curr Biol 16:279–280 41. Vallortigara G, Regolin L, Marconato F (2005) Visually inexperienced chicks exhibit a spontaneous preference for biological motion patterns. PLoS Biol 3(7):1312–1316

.

Evolution: Remarks on the History of a Concept Adopted by Darwin Volker Gerhardt

Abstract Evolution is a term invented by the Philosopher Gottfried Wilhelm Leibniz at the beginning of eighteenth century. Referring to the latin verbum evolvere, “evolution” means the step by step development of the organism from the ovum up to the grown up exemplar. This conception includes the thesis, that all organisms were totally preformed in the first real exemplar of living being at all. This thesis was sharply criticized by Immanuel Kant. He saw that there would be neither learning nor variation in history of life when Leibniz should be right. But in his political and cultural philosophy Kant contrasted “evolution” against “revolution” and gave it the meaning of a continual historical development. It was this understanding that influenced Darwin in choosing evolution for his description of the process of natural development. So one of the fundamental concepts of the modern science of nature is derived from philosophy, but not in its biological sense in the tradition of Leibniz, but in the political dimension as Kant pointed out.

1 The Rediscovery of Nature in Culture There was a time when it was thought that society could subsist in and of itself. Nature was taken to be the ultimately indispensable substratum for everything that happened, but it was not thought to have any significance for the assessment of human action. It seemed that knowledge of nature could only put to technical use and was thus considered to be deficient, like technology itself. It was only accorded any significance as a fact, something we could supposedly only refer to “positivistically” and that was only thought to have instrumental significance. Human action, in contrast, was thought to depend only on what was considered societal and historical and could be criticized in terms of political notions.

V. Gerhardt (*) Institut f€ur Philosophie, Humboldt-Universit€at zu Berlin, Berlin, Germany e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_13, # Springer-Verlag Italia 2012

201

202

V. Gerhardt

That we have overcome this way of thinking is due not least of all to Charles Darwin. There are obviously other factors that played a role, such as our realization of the scarcity of natural resources, the susceptibility to epidemic diseases or the increasing threat of natural catastrophes with the growth of civilization. But is essentially thanks to the theory of evolution that today we see nature, technology, society and culture as a differentiated but unified and interconnected whole. As I hope to demonstrate, this relates not just to the theory of evolution but to the very concept. For the concept itself opens a historical dimension that binds together nature, society and culture. But what the theory of evolution accomplished was to historicize nature, both in its process and in its products.

2 The Historical Constitution of Life The theory of evolution was not strictly necessary for us to see the interconnectedness of nature, history, society and culture. In its earliest beginnings philosophy started from the assumption of the unity of the cosmos, taking it as self-evident at first and then later explicitly establishing the point. The ancient materialists as well as Plato and Aristotle had already drawn inferences from the conception of an origin to a theory of development. In the modern era these ideas were worked out in greater detail, primarily under the influence of Newtonian theory, and by the beginning of the eighteenth century they had been elaborated into a natural history. The young Kant had even explained why one could only treat of a “theory of the heavens” within the framework of a “general natural history” that encompassed the development of the earth and even of the life on earth. Biology also began with the assumption of a unified origin of all life and saw no reason to exempt humanity and the human mind from the events of life. This is even rooted in the very method of biological classification: for the researcher seeking to identify and organize genera and species, the individuals are only examples illustrating what is significant for the character of the species. In fact, as much as biology deals with the individual organism, it is ultimately oriented towards the general forms of life, of which the individuals are merely representatives. If we turn this around and say that the forms of life are themselves always representations of individually inherited traits, we can see how close biology is to the central problem of the social and cultural sciences, since it deals with the general characteristics of individual phenomena of life that not only outlast the existence of their individual instantiations but shape and guide them. And if this includes social formations such as pairs, packs, herds, swarms, and colonies, it becomes clear that as soon as biologists turn to humans (a mammalian species), they have to take into account our social, moral, religious, and political accomplishments as well. Thus methodologically biology occupies the same territory as the social and cultural sciences. That the cultural accomplishments of humanity – including

Evolution: Remarks on the History of a Concept Adopted by Darwin

203

technology, stemming from the appropriation of individual natural processes whenever conducive to life – belong to one reality, cannot, in any case, be a controversial proposition within philosophy. Nonetheless, Darwin’s theory of evolution brought greater depth and clarity to this insight. It advanced our knowledge of the interconnectedness of nature, life, technology, history, society and culture. More than that: from its very beginning it involved questions of cultural evolution. In what follows I hope to make this clear by means of a small detail in the history of the concept.

3 The Origin of the Concept in Leibniz In } 74 of his Monadology, the founder of the Prussian Academy of Sciences, Gottfried Wilhelm Leibniz, speaks of a problem that had already troubled philosophers before his time, and tries to resolve it with recourse to the latest research results involving the microscope: Scientists have had great difficulties over the origin of forms, entelechies or souls. But now that meticulous research has been carried out on plants, insects, and animals, it has been recognized that naturally organic bodies (les corpes organique de la nature) are never the product of gas or rotting, but always of seeds (semences), which undoubtedly contain some sort of preformation. The conclusion has been drawn that, not only does the organic body already exist before conception, but also a soul in this body – in a word, the animal itself (l’animal seule). The only function of conception is to precipitate a major transformation, so that the animal becomes an animal of a different species. Even outside the process of generation, something similar is observed when maggots become flies, or caterpillars become butterflies

We can see this proposed solution, published in 1714, as an equally metaphysical and biological reaction to the increasing interest within the sciences in questions of the anatomy and physiology of the human body as well as in the problems of life per se. Thus it is not surprising that it is precisely this passage from the Monadology that generated a great amount of interest and played a not insignificant role in developing the problems that contributed, in the course of the eighteenth century, to the founding of that science that soon came to be known as biology. These questions revolve above all around what Leibniz called de´veloppemens, “developments”.1 This primarily concerns the thesis of preformation advanced in the text, that is, the claim that the peculiar characteristics of a living being are already determined at the time of its formation. We can see the range of variation that Leibniz allows for when he refers to the metamorphosis of the maggot to the fly and the caterpillar to the butterfly. At the same time he believes that the traits that are decisive for heredity and way of life are

1

Leibniz contrasts de´veloppement with enveloppment, the degeneration or decrease in the living forces. De´veloppement unwraps that which had previously been enveloped.

204

V. Gerhardt

originally inherent in the organism at the time of its formation and unfold themselves into their characteristic form (such as that of a horse, a cow or a human) during growth and maturation. Development is just a process of unfolding of that which God put into the world in the form of countless monads, a process that recurs anew in each individual.

4 On the Sense of the Metaphor of Evolution Leibniz had already used the term “evolution” to describe this ontogenesis of the individual living being from the microscopic elementary traits that it came equipped with, and the term began to circulate in the eighteenth century, first in Latin treatises and then increasingly in the French.2 Some time before the French Revolution other European national languages began to follow suit. In Latin “Evolution” was already an artificial coinage, derived from evolvere, which had originally meant to unwrap, to unfold and was generally used in reference to the unrolling of a scroll. The opposite is envelopment, to enfold or envelop. It means death. De´veloppement or evolution unwrap that which had already been placed inside. This is the original sense of the word that the theory of evolution takes its name from.3 This etymology brings out the process of enlargement as well as that of becoming visible and knowable, aspects that are a prerequisite for any adequate understanding of the concept of “evolution.” This persists today in the concept of the phenotype, which brings the genotype into view. Moreover, the unfolding (of a leaf) or unwinding (of a scroll) has a certain proximity to reading, which can be almost taken literally today since the progress of evolution can essentially be “read off” of the genetic sequences. Thus the term evolution refers first of all to the unwrapping of the inherent traits of a living creature from its embryo to the matured living individual. But the preformation thesis at the same time extends the term to include the sequence of generations, since the embryo only comes into existence through the merging of ovum and spermium and bears the traits of at least one parent. Thus it was thought there had to be a line of continuity leading back to the first parents driven from Paradise. Yet things didn’t end with this first sense of the term. Rather, the explanatory power Leibniz hoped to achieve for the generation of individuals met with a decisive critique in the emerging biology in the late eighteenth century and in the philosophical theory of life with which Kant brought new life to the thought of his age.

2

Wolfgang Wieland: Entwicklung/Evolution, in: Geschichtliche Grundbegriffe, eds. Brunner et. al., vol. 2, Stuttgart 1992. 3 Evolvere also had the meaning of driving out and displacing, both of which recur in the later theory of evolution, namely in the survival of the fittest and in the process of selection.


205

Thus it came about that Darwin did not name his theory of inheritance after the term that Leibniz had meant biologically in his Monadology, but rather took up a concept of evolution with a philosophical application to culture and history. Hence the prospect of a cultural evolution is inherent in the use of the concept prior to the emergence of Darwin’s theory.

5 Kant’s Critique of the Concept of Evolution In } 81 of his Critique of Judgment, a book that offers, in its first part, an aesthetics based on the experience of life, and in its second part a comprehensive theory of life compatible with the causal explanations of natural science, Immanuel Kant distinguishes between educt and product. He sees product the way we see it today: as a new creation of nature with its particular origin and its individual character. Every technical production can be taken as a product, but every living creature can also be seen as a product, as something newly created, as we still do today. On Kant’s account we are only justified in this so long as we do not do so on the basis of the “theory of evolution” founded by Leibniz.4 As Kant shows in his detailed examination of its central theses, the theory actually does not allow anything new. According to this theory of evolution, the only thing that develops is the seed that had already been inherent in the sequence of generations from the very beginning. This “theory of evolution” should really be called a “theory of involution” – a theory of nesting that in each individual only acknowledges that which must already have existed in the origin of life. If this origin is to have any efficacy, the theorist of evolution who follows Leibniz has to have recourse to something supernatural, a “hyperphysics,” in order to explain how the seed containing in advance each living creature can have come into nature in the first place – at least according to Kant. Thus Kant sees a contradiction between the preformation theorem of evolutionary theory and the facts of life, a contradiction that cannot be reconciled under the conditions of modern physics. For life brings forth something new with each newborn creature. For Kant the metaphysics of evolution is not able to acknowledge the innovative productivity of all that is alive.

6 Three Knock-Down Objections The general objection from any thinker who insists on the unity of nature is reinforced by three points that we could call the life-world objection, the phenomenological objection and the biological objection.

4

Kant. Kritik der Urteilskraft, } 8, Akademie-Ausgabe 5, 423.

206

V. Gerhardt

First Kant notes that the hypothesis of involution makes “copulation . . . a mere formality”.5 If the individual with all of its traits is already contained in one cell, then the addition of a second cell can hardly be more than an external impulse. Maybe it serves as food? – at any rate this hypothesis has some plausibility if we assume, as Kant does, charitably as it seems, that the preformed embryo is located in the male sperm cell and the nutriments in the egg. The “proponents” of Leibniz’ position, as Kant ironically notes, proceed from the contrary assumption and thus have to explain how the male sperm could play any role whatsoever. Kant’s second objection is founded on the pervasive interdependency of nature throughout all its processes and notes how the involution hypothesis of the Leibnizian theory of evolution interrupts precisely these elementary interconnections: if Leibniz were right, there could be no interaction between the embryo and its environment. A “great number of supernatural arrangements” would be necessary to preserve the “embryo formed in the beginning of the world” from any harm that might come from the surrounding forces. Thus the influence of hyperphysics in the world would not just be limited to its beginning but would be required again and again. The third objection is less theoretically elaborate but not any less decisive: if Leibniz’ theory of evolution were correct, there could not be any “hybrids.” Hybrids “could absolutely not be accommodated with the system of preformation.” In this system the male seed would serve as nourishment for the embryo, but would not exercise any “purposive formative power,” which is impossible according to the premises of the theory of evolution.6 Following these objections, each of which is a knock-down argument, Kant opts for a theory that sees living creatures as true products of nature, which in their individual development are subject to the influence of ongoing forces. On this theory living creatures are generated in accordance with the “principle of an original organization,” for which he assumes the productive potency of a “formative impulse”.7 Kant outlines a theory of self-organization that is still current today, a theory that sets out the natural conditions for his ethical theory of self-determination – though I cannot discuss this in any more depth here.8

5

Ibid. Ibid., 424. 7 € Ibid. – Kant is probably drawing on the second edition of Blumenbach’s text Uber den Bildungstrieb und das Zeugungsgesch€afte, G€ ottingen 1789. For more on the historical and systematic context of these considerations see: Siegfried Roth, Kant und die Biologie seiner Zeit, in: O. H€offe (ed.), Immanuel Kant: Kritik der Urteilskraft (Klassiker auslegen vol. 33), Berlin 2008, 275 – 288. 8 See V. Gerhardt, Selbstbestimmung. Das Prinzip der Individualit€at, Stuttgart 1999. 6


207

7 Evolution as an Alternative to Revolution If history followed a rational course founded on human insight, the concept of evolution would have ended its career in the year 1790. Kant shows that the concept as Leibniz understood it is unsuited to comprehend the essential aspect of life, namely that something new continually emerges with and in each individual. But of course the surprising thing is that its career only really took off at that moment – and with Kant’s help. For he not only continued using the concept after having shown its unsuitability in the context of biology, but opened up a new field of application for the concept in his theory of history and culture. He did this by transferring the concept to the developmental dynamics of human civilization. And it is, in fact, a quite significant question how we should conceive the continuous development of law, if its conditions, namely freedom, equality and the autonomy of individuals, are to be preserved throughout. Kant believes that only the republican principle of law and the monopoly on violence necessarily joined with it can give the future of humanity a self-determining form. Education, morality and religion are indispensable, but they cannot do very much to bring about progress in human culture that at the same time allows for the validity of the law of each present era, if nothing ensures the continuity and stability in this development.9 But securing a future in freedom, equality, and autonomy, requires the continuous security of the principles of law and a form of the state that is capable of ongoing selfimprovement. This also requires that “the state reform itself from time to time and, attempting evolution instead of revolution, progress perpetually toward the better.”10 Here we have the new use of the concept – it refers to a perpetual progress within the course of a history determined by humanity itself. Strictly speaking it describes the political maxim to avoid revolutions. And it is only in transferring this normative conception to the course of historical developments that “evolution” is made into a descriptive term used to represent an internally cohesive historical course – without break and without revolutionary upheaval.

8 Revolutions in Nature Kant had widely-read precursors for this normative political and historically descriptive use of the concept of evolution in his students Herder and Erhard.11 Both draw on considerations from early Kant and inspired their teacher, who had

9

Kant, Der Streit der Fakult€aten (1798), 2. section 10; Akademie-Ausgabe 7, 92 f. Ibid., 93. 11 A few pages before this quotation Kant acknowledges his student Erhard. He speaks of the gradual development of the moral traits of humanity, which are more and more capable of taking 10

208

V. Gerhardt

since advanced in age; for in his early Cosmology and his first lectures on Physical Geography he presented the formation of the cosmos and the development of the earth has an ongoing event of natural history – though without using the concept of evolution. This historical use of the concept of evolution in application to politics, society and culture persists even today. “Evolution” is the opposite of “revolution” – although there has also long since emerged an understanding of revolutions as something that can occur over longer periods of time, such as the industrial revolution or the scientific, technological, or so-called sexual revolution. Incidentally, Kant was already familiar with an understanding of revolutions as spanning longer stretches of time, as shown by a remark in the Critique of Judgment. He is particularly close to Darwin in this remark: after the great eras of the formation of the solar systems with their cooling planets, the longer periods of earth’s history saw recurring spurts in the development of life. First the seas are populated, then life colonizes the swamps and finally living creatures succeed in conquering the land. Kant calls these cataclysms in the developmental history of life the “oldest revolutions,” of which only “traces” survive, which the “archeologist of nature” is to follow. In this context the earth is apostrophized as “universal mother,” as a “womb” and as the “motherly womb”.12 Eight years later Kant would have been able to say that these revolutions of nature are not contrary to the thought of an evolution of life on earth. This is of course an evolution that cannot be understood according to Leibniz’s proposal, but rather only according to Kant’s own model, which can be transferred from an understanding of continuous societal developments oriented around principles to an understanding of nature – even though there are no legal principles and constitutions in nature. But there are law-like regularities that belong to the mechanics of nature and the self-organization of life. In transferring the concept of evolution, which initially describes a political maxim for the peacable achievement of reforms, to the development of culture, Kant strips away the biological significance that Leibniz had meant the term to have. Yet by way of a detour through a speculation about the entirety of the dynamics of society, wherein Kant sees a continuation of nature with other means, he gives back to the concept its connection to life. Within his critical system, society, politics and culture do not just stand alongside nature unrelatedly. Rather the ongoing progress of civilization should bring together nature, society, politics and culture into an alignment that is not just retrospectively recognized but also prospectively hoped for. This is possible if humanity makes the antagonism of

part in the destiny of the race: “This even is the phenomenon of, not of revolution, but (as Erhard expresses it) a phenomenon of the evolution of a constitution in accordance with natural law”. (Akademie Ausgabe 7, 87) The reference to the text of his enthusiastic adherent Johann Benjamin € Erhard, Uber das Recht des Volks zu einer Revolution, Jena 1795, shows how new this use of the concept of evolution for historical and cultural theory still is for Kant. 12 Kritik der Urteilskraft } 80; 5, 419.


209

nature productive in itself and proves capable of self-determined development of their natural traits in regulated competition and legally organized opposition.

9 Darwin as the Heir of the Full-Fledged Concept Once we see how Kant strives to bring together a dynamically conceived nature with the unfolding of human culture and to unite this in turn with the development of law, it would be quite erroneous to say that he removes the concept of evolution from nature and gives it over entirely to self-determined political movement. Rather, in Kant’s critical philosophy the concept is available as a means to interpret all events that change over time. And my concluding thesis is that Darwin assumed this concept of evolution, though hesitantly, to describe his theory. What is noteworthy about this conceptual history is that Darwin began with a concept that was quite loaded with connotations from politics, the philosophy of history and cultural theory rather than using, say, a biologically restricted term. The Origin of the Species and The Descent of Man take up the concept of evolution in its most comprehensive sense and from the outset bring together the problems of the natural history of life with all aspects of plant, animal and human behavior. Consequently it should not come as a surprise that Darwin came to write about the problems of the emergence of human expression and of the feelings, of empathy and even the development of morality, and did so from within the logic of his own conception. Darwin worked on a description of the transitions between nature, society and human culture with the same intensity with which he sought to understand the selective and diversifying mechanisms in the development of the species. For him life does not stop short of the phenomena of history. He is also able to give a place in the life of humanity to philanthropy and religion. For this reason his theory obliges anyone who takes it seriously not to break life down into an organic substratum and a purportedly intellectually aloof superstructure, but rather instead to uncover the dynamic unity between the mechanical and the organic forces. This is also the source of the obligation not to let the sciences themselves come asunder into contrary cultures. Instead they must recognize that they arose from the necessity of self-guidance in human culture and thus have to assume the responsibility for their self-organization in coordination with societal forces. The most important argument for the unity of the sciences follows from the fact that evolutionary theory can prepare us like no other to see how that which we call “intention,” “need,” “meaning,” “sense,” “consciousness” or “mind” arose from the natural development of life. Darwin enables us to finally give the functions of reason their position and role in life rather than having to derive them from their own premises (in the always unsatisfying form of self-confirmation). Thus reason does not have to keep repeating why it holds itself to be so important if it can see how it became necessary and under what conditions it is in fact

210

V. Gerhardt

indispensable. I believe that evolutionary theory can liberate reason from the burden of its thousands of years of self-confirmation and lead it back to the conditions that preceded it that are themselves not yet rational. But they might show us why reason is neither so unreasonable nor so irrelevant as it can seem from the perspective of its critics. I cannot think of any other problem that the natural sciences and the humanities should take a greater interest in. For it is in the natural elucidation of the origin and the potential achievements of reason and consciousness that both fields have the chance to shed light on themselves as well and to clarify why they not only emerged from the same impulses of curiosity, knowledge, and rational guidance, but continue to depend on one another.

10

Addendum

Darwin’s results also began the mediation of the dispute between Kant and Leibniz. For Darwin’s development of the theory of evolution showed that our genes contain those enduring instruments of control of life that demonstrate a surprising constancy despite their mutability through mutations. The genetic control of life secures both continuity and variability. This result is not just interesting for the history of philosophy. It should also appease the Berlin-Brandenburg Academy of Sciences. For Leibniz and Kant were both members of its precursor, the Prussian Academy of Sciences. Darwin reconciled them.

An Evolving Research Programme: The Structure of Evolutionary Theory from a Lakatosian Perspective Telmo Pievani

Abstract The main topic of the paper is a discussion of the ways through which the theory of evolution remakes itself, changes and grows, keeping alive and reinforcing its Darwinian explanatory core. The theory shows a 150 years old history of theoretical and empirical extensions and revisions, without any apparent radical change of “paradigm” and without a rival Research Programme able to replace it. The ongoing transition from the Modern Synthesis (MS) to a so-called “Extended Evolutionary Synthesis” (ES) is here interpreted through the Methodology of Scientific Research Programmes, proposed by the epistemologist Imre Lakatos and updated. The current situation in evolutionary biology could be represented by a “progressive” shift of the Darwinian research programme, moving from the quite rigid theoretical framework of the standard version of Modern Synthesis (gradualism, extrapolationism, adaptationism) to the more inclusive and pluralistic “core” and “protective belt” of the Extended Synthesis. Promising and advanced researches – like those concerning evolutionary developmental biology (Evo-Devo), epigenetics, multiple ways of speciation and the role of structural internal constraints – find in this perspective a realistic interpretation as theoretical and empirical novelties with huge implications, nevertheless not incoherent with an extended Neo-Darwinian explanatory core. A Neo-Lakatosian approach seems useful when we discuss the extension of evolutionary models in non biological fields, avoiding the application of just metaphorical forms of “ultra-Darwinism.” This analysis in terms of a rational and continuous dynamics of growth of biological thought seems much needed also for a critical examination of some popular and radicalized controversies about the health of a no better defined “Darwinism or Neo-Darwinism.”

T. Pievani (*) Philosophy of Science, University of Milano-Bicocca, Milan, Italy e-mail: [email protected] A. Fasolo (ed.), The Theory of Evolution and Its Impact, DOI 10.1007/978-88-470-1974-4_14, # Springer-Verlag Italia 2012

211

212

T. Pievani

1 What Makes Biology Unique (and What It Does Not) The elements of uniqueness and epistemological autonomy of evolutionary biology (or, better, of the set of evolutionary fields), firstly outlined by Ernst Mayr [33], could be updated today in the following lines: • The apparent absence of universal “laws”, due to the abundance of descriptions and singular existential assumptions; • The historical nature of the explanations (narrative dimension, historical contingency, the role of chance, unrepeatable events, irreversible processes); • The diffusion of objects of study with features of uniqueness, ambiguity in definitions, unlikely to be categorized and ascribed to an unambiguous set of phenomena; • The nested multiplicity of spatial-temporal levels of analysis and the stratified hierarchy of non-reducible patterns of explanations (like in the case of emergent properties between different levels of organization, or in the case of different spatial and temporal focalizations between macroevolution and microevolution, with the need to integrate non reducible patterns emerging at the nested levels of genes, cells, organisms, populations, species, ecological systems and so on). Nevertheless, it is interesting to observe that now three other elements of “uniqueness” (in a negative sense, with respect to the epistemological status of physical sciences used as a model) are no longer considered as crucial, because of the ways through which the theory of evolution is able to deal with “evidences” today [57]: • The alleged impossibility of falsification of evolutionary hypotheses, avoided thanks to the strongly convergent evidences coming from very heterogeneous fields like paleontology, comparative anatomy, molecular biology, cladistics, paleo-ecology and others; using such convergent proofs, the evolutionary reconstructions could be compared and discussed in terms of parsimony (like in the case of phylogenies) and explanatory power, selecting alternative models case by case; • The alleged absence of experimental methodologies based on the repeatability of experiments and the modulation of parameters in laboratory (researchers can simulate and experiment selective pressures acting on populations of microorganisms, observing in laboratory dozen of thousands of generations with their mutations and rates of genetic change; evolutionary developmental biology and synthetic biology are pushing ahead the experimental status of evolutionary researches, with the possibility of tuning the molecular parameters of living beings, and in other fields like cognitive ethology and evolutionary psychology it is time for an extensive use of comparative behavioral experiments in different experimental situations); • The alleged incapacity to produce genuine scientific predictions: this is not the case anymore, when several evolutionary disciplines have predictive models

An Evolving Research Programme

213

testable both in ecological fields, and even now in the wild [23], and in laboratory with micro-evolutionary experiments. The relatively recent adoption of “classical” experimental procedures cannot justify, anyway, a reduction of the evolutionary biology to the epistemological status of mathematical and physical sciences (status itself evolving). The “mimicry” with physics is not realistic when we have to deal with historical, hierarchical and singular processes. Not only past evolutionary events, but also current phenomena like speciation, are unlikely to be observed and reproduced in laboratory. It seems more convenient to outline a specific epistemological status for evolutionary researches – different, and certainly not weaker than those of other disciplines – where reproducibility and classic experimental verifications represent a subset of the methodologies that evolutionists should adopt, including the consilience of heterogeneous evidences (like in the case of the “total evidence” approach to phylogenies), comparative proofs, a multiplicity of coherent observations, historical reconstructions based on direct and indirect evidences coming from several local disciplines. Only this articulated set of methodologies seems able to manage such a complex and interdisciplinary empirical basis. So, • The modern theory of evolution explains a huge amount of single, verifiable facts, in the past and present, and frames of verifiable facts; • These facts are logically connected and produce coherent frames of corroborated evidences; • These connections of explained facts allow to formulate “risky” predictions and retro-dictions, both verifiable or falsifiable with new facts, enlarging progressively the empirical content of the theory through a process of criticism and growth of knowledge. What could we say about the structure of a scientific theory able to do that? The elements of uniqueness, above described, usually expose the reconstructions of the history of biological thought to quite appealing “radical” interpretations of the ongoing theoretical changes, as if we had more “theories” of evolution or, even, more alternative “languages” on the field. This is the case of the call for the concept of “paradigm”, in Thomas Kuhn’s sense [28], in the description of the history of the different stages of the theory of evolution after Darwin. According to Mayr [33], paradigm is too strong a concept in order to understand the theoretical fluidity and the heterogeneous basis of empirical facts that we find in natural history. Like Massimo Pigliucci recently noted [53], there is nothing in the field at the moment that could suggest the typical features of a “paradigm shift” between incommensurable explanations and conceptual languages. If we would say that the current theory of evolution is a “paradigm”, actually we do not see the accumulation of serious anomalies and the dogmatic crystallization that should precede a paradigmatic crisis. What is typical of the field is, on the contrary, the fact that new problems and apparent exceptions can be resolved and understood mainly through integrative explanations, different modulations of the empirical domain of application of already established patterns of explanation, new

214

T. Pievani

calculations of the relative frequency of a pattern with respect to another. It means that the dynamics of growth and evolution of the theory is based on processes of theoretical extension and empirical enlargement of an elastic set of explanations already consolidated but constantly needing adjustments and integrations [2]. Something completely different from a “revolutionary” overthrow. Does it mean, conversely, that we are in the middle of a static and prolonged period of “normal science”, with just marginal scientific puzzles to be solved? Not properly. An articulated set of explanations that brings together heterogeneous facts, absorbs new facts, updates its theoretical toolkit when it is healthy, or accumulates anomalies and auxiliary hypotheses when it is sick and it plods along the experimental novelties, was defined neither simply a “theory”, nor a “paradigm”, but a “scientific research programme” by epistemologist Imre Lakatos [29]. It means that the evolutionary explanation is submitted to continuous changes, even very deep sometimes, and appears like an open and busy yard, not like an old, traditional building. So, the theory of evolution is evolving, or better, the evolutionary scientific programme is evolving. But how exactly? Along which lines? What is under potential falsification here is not a single concept or the content of a single theory, but a succession of theories and integrated models: in other words the rational dynamics inside the process of updating and redefinition of a coherent whole of explanations, included the strategies of defense against contrary evidences and apparent contradictions [29, 37]. The process of criticism and growth of the evolutionary knowledge after Darwin seems a continuous one – made by extensions, revisions, and even reversions to originally Darwinian insights [9] – and not a discontinuous, paradigmatic one. Without any underestimation of the importance of external, social and psychological, factors in science, the pivotal course of the conceptual change is an internal, logical one, depending on new corroborated evidences and theoretical advancements.

2 How Many “Darwinisms”? A flexible structure of the evolutionary scientific programme suits with the standard pattern of the history of biological thought very well, intended as a succession of stages of integration, revision and expansion. Synthetically: • The originally Darwinian explanatory frame, structured with: (a) a wide descriptive apparatus (evolution as a matter of fact, common descent with modifications, the tree of life); (b) an integrated set of multiple explanatory factors, such as individual and non-directed variations, natural and sexual selection (the variation-selection core), and Lamarckian “residuals” (where each concept has had afterwards a different fate – [31, 32]); (c) some meaningful risky predictions and retro-dictions, with different fates as well (about the depth of time, the pervasive gradualism, the hypotheses concerning the evolution of complex structures, the role of geographic isolation); (d) a powerful cultural


215

revolution, but technically not a paradigm shift, being rather a transition from pre-scientific views like natural theology and the entry of the first general scientific programme in evolutionary fields (adopting already circulating idea, but in a new and wholly naturalistic explanatory frame). • The original “Neo-Darwinism” (term coined by George J. Romanes, a pluralistic Darwinian, interested in ethology and evolution of the animal minds, and used also by scholars like Alfred R. Wallace and Asa Gray), at the end of the nineteenth century reinforces the Darwinian core, removes the Lamarckian residuals and establishes with August Weissman the bases for the conceptual separation of hereditary biological materials and their bearers, giving to natural selection a quite exclusive explanatory priority. • The Evolutionary Modern Synthesis (MS) – preceded by a phase of eclipse of Darwinism (according to Julian Huxley, 1942, and then [3]) during the re-naissance and rediscovery of Mendelian genetics and the birth of macro-mutational and saltationistic theories of biological change – could be represented as a kind of powerful “Neo-Darwinism of second generation”, with the fusion of Mendelism and population genetics, the first mathematical models for the changes in the frequencies of genetic variants in populations, and a genetic theory of natural selection; at that time, the convergence of two traditions of research created the first global evolutionary scientific programme, with a strongly coherent theoretical frame (the variation-selection core), a great expansion of predictive power, entire new fields of evidences for the Darwinian core of the theory of evolution; at the same time, the synthetic power of MS was reached through a crystallization around few methodological assumptions (in some cases so strong and normative, especially in worldwide handbooks, that they seemed quite “paradigmatic”), like the extrapolation of any macro-evolutionary phenomenon from micro-evolutionary processes, gradualism and uniformitarism, a diffused adaptationism [20], the underestimation of evidences (with exceptions in single authors – [35]) coming from embryology, ecology and human evolution [16, 45]. • Since the sixties of twentieth century, we see a new rapid extension of the empirical basis of evolution, together with technological advices, because of the molecular revolution, the acceleration of genomics and post-genomics, the new detailed phylogenies, the role of the evolutionary developmental biology (Evo-Devo), the growth of epigenetics, and there is a general consensus about the fact that we are in front of a “contemporary Neo-Darwinism”, the third generation, quite different from the previous ones. Disciplines less highlighted in MS, embryology and ecology, are acquiring their deserved, lost centrality. But mostly, MS was subjected to deep theoretical challenges, like neutralism, Punctuated Equilibria, and now Evo-Devo itself. The assimilation of these challenges and the metabolism of such a huge amount of new data were much slower and harder than any other passage in the past decades, and claimed a profound change in the structure of the evolutionary scientific programme. So what kind of “Neo-Darwinism” do we have today in the field? Do we need a completely new Evolutionary Synthesis or will some superficial restyling

216

T. Pievani

be enough? Is the new structure of contemporary Neo-Darwinism already stabilized or in a phase of transmutation? The Lakatosian methodology of the Scientific Research Programmes (SRP) seems the right candidate in order to understand the ongoing transition. With respect to the alleged incompleteness of MS frequently addressed in contemporary debates, it seems quite clear that MS showed a great capacity of inclusion [2], through processes of theoretical assimilation that enlarged its empirical basis and prevented logical and explanatory objections. But, in a first phase, this assimilation produced the need for a more pluralistic way to understand the rhythms, the units and the levels of evolution. In the case of Punctuated Equilibria theory [15], after decades of debates the general consensus around the mechanisms of speciation is that we need a multiplicity of processes and modes of birth of new species (punctuated in some ecological circumstances and gradual in others), a multiplicity of possible rates of speciation, and a multiplicity of levels of change (from an ecological and a genealogical point of view) to be considered [8]. So the main methodological stance today is a calculation of the relative frequencies of one pattern (punctuationism) with respect to another (gradualism and trends) [44], and not a radical alternative between two incompatible patterns. What we see is precisely a balance between points of breaking of past methodological stances inside MS (like phyletic gradualism) and points of theoretical continuity. In the case of Punctuated Equilibria, the points of breaking are: punctuations are not due to imperfections of the geological record; speciation is not only anagenetic, but frequently cladogenetic; speciation is connected with major episodic evolutionary changes; the wide diffusion of apparent stasis in natural histories. The points of continuity with MS are: the evolutionary mechanisms in action during the speciation are Darwinian; gradual trends (plurality of patterns) are not excluded; and mostly, punctuation and stasis stand at the level of geological scale of species life, so they do not clash with normal mechanisms of change at the level of populations of organisms [20]. A quite similar process of assimilation of new evidences with a consistent internal theoretical accommodation is at the core of the history of another challenge to MS: neutralism [26] and contemporary weak-neutralism. In the frame of a renewed MS the evidence of a huge amount of variations and sequences inside the genome with no adaptive and selective origin is accepted with the cost of a robust quantitative and mathematical integration in the models. Neutralistic patterns based on drifts and on structural internal mechanisms, non selective at the level of organisms, show that natural selection is not the exclusive factor of genomic change, but an important one among others. Like in the case of punctuationism, we need a calculation case by case of the relative frequencies of selective patterns and drift patterns when we look inside the structure of the genome. A quite different example is the challenge posed by the discovery of the crucial role of macro-evolutionary patterns in evolution (like turnover pulses of species, rapid adaptive radiations, mass-extinctions), because it breaks the strong


217

methodological assumption that every macro-evolutionary phenomenon should be extrapolated by the uniform accumulation of micro-evolutionary processes. The integration needed seems more and more profound. Other recent fruitful fields of researches threaten the capacity of inclusion of MS, because they touch fundamental ribs of the theoretical architecture of MS or in some cases add entire new domains of experimental evidences that claim for a powerful theoretical updating: • The discovery of families of genes and hierarchies of genes, with a still up to now underestimated complexity of the genetic regulation, changes the idea itself of the genome, the machinery of the mutations and the phenotypic effects, the definition of the concept of “gene”; so, the “raw material” of any evolutionary process is no longer so “raw”; • Evo-Devo suggests a crucial role for the constraints to variation, for the internal developmental constraints, for systems innovations, functional cooptations, changes with a modular logics [5, 18, 34, 36]; • The field of epigenetics enlarges the range of the sources of variation and inheritance [24]; • The phenotypic and developmental plasticity modifies the relationships between genomes, phenotypes and ecological niches [51, 62]; • The “niche construction” hypothesis [40] is a new, constructivist, way to see the active role of the organism in evolution and the reciprocal modifications of organisms and niches; this idea fits with the Developmental Systems Theory [42, 43]; • The concept of “evolvability” is evolving itself [27, 52]; • The generation of order and structural complexity through mechanisms of biological self-organization is real and deserves attention [25]. For each of these lines of researches we need more data and a careful consideration of the real theoretical impact. Anyway, the capacity of painless assimilation of scientific novelties by MS seems to be progressively declining. The problem is no longer of partial “incompleteness”, but the adequacy of the whole conceptual structure of the theory [20]. Maybe we need a new kind of Neo-Darwinism, revised and extended. Using the methodology of Lakatosian SRP, we argue here that the transition in progress from the MS to the so called “Evolutionary Extended Synthesis” (ES) [55] could be represented as a shift from a previous evolutionary research programme (ERP1), turned to be “regressive”, and a new evolutionary research programme (ERP2), with an extended Neo-Darwinian core and a protective belt of new assumptions and auxiliary hypotheses with a pluralistic and integrative explanatory approach.

3 Core and Protective Belt of a Scientific Research Programme According to Imre Lakatos, the growth of the scientific knowledge is a process quite independent from the mind of a single scientist: the product of the discovery becomes autonomous from the mental activity that created it, like a growing living

218

T. Pievani

organism with proper laws of development. So the history of science could have internal rational reconstructions, with an acceptable degree of objectivity, a logical, continuous, internal dynamics of change through criticisms, new assumptions, extensions and revisions. As we have seen, the term “theory” appears inadequate to depict the current state of the evolutionary programme of researches in different fields and with several integrated patterns of explanations (better than separated “concepts”, like in [32]). How does a corpus of explanations with these characteristics evolve and transmute? In Lakatos the continuity of the history of science is given by the transformations of scientific research programmes, that are sets of models, concepts and hypotheses delimited by the choices of a community of scientists: firstly, they establish a complex of theoretical postulates and corroborated explanations which are no more subjected, in the practice of research and publications, to falsification. This operative and methodological choice gives birth to the “core” of the RP. Of course, the core is un-falsifiable exclusively from a methodological point of view, not in principle: the scientists decide (according to an “inductive conjectural principle”) that a core of explanations is confidently corroborated and reliable, and go ahead. The choice, in this “sophisticated fallibilism”, is pragmatic, provisional and risky, and any rival RP has the duty to hit and weaken the core. The inductive reliability of the core has two criteria: the additional empirical content (predictions of new facts); the corroboration of the additional empirical content (the predictions indeed increase the empirical content of the RP). Though the corroboration will never be ultimate in science, the pragmatic preference for theories scientifically healthy is rational because they are conjecturally reliable. The core contains also the influent metaphysics of the RP, driving the researches through the great iconographies and metaphors of the RP, the philosophical views, the initial assumptions. The core produces the heuristic rules that indicate the ways to be taken (positive heuristic) and the ways to be avoided (negative heuristic). These aspects of the core reveal a “kuhnian” mood and a defensive tenacity, but the structure of the core can evolve continuously, depending on the anomalies emerging and on the fight with rival RPs, nevertheless always keeping its physiognomy and peculiarities. So the defensive tenacity is not dogmatic and blind, but articulated in a continuous requalification of the core through the heuristic. The followers of a RP cannot insert everything in the core, because its formulation should respect a historical criterion (a long process of “proofs and refutations”, trials and errors – [30]) – that is, a series of successive, refutable models, able to predict new facts – and a normative criterion, according to which the responsibility of the choice is in charge with the scientists of the RP, and the success of the RP will be evaluated by its empirical results. Then, with their creativity, scientists surround the core with a “protective belt”, made by auxiliary hypotheses that protect the core and nourish its evolution. The protective belt is made also by observational theories, initial conditions, open problems, provisional hypotheses, other conjectures, and must tolerate the external attacks by rival RPs thanks to continuous modifications, adaptations, refutations and auxiliary hypotheses able to absorb anomalies and


219

predict new facts. The crucial difference is that the protective belt is by definition fallible, unceasingly mutable, and its specific contents are not vital for the survival of the whole RP. In its early phases, the protective belt is composed specifically [38, 39] by assumptions of negligibility (neutralization of facts considered non essential for the study of the phenomena explained by the RP), assumptions of domain (the external application of the RP to other kinds of phenomena, keeping the RP under control) and heuristic assumptions (defining the problems that the RP does not intent to deal with, the anomalies considered non essential, the risky, provisional ad-hoc hypotheses). If the heuristic is fruitful and acts on the protective belt modifying the hypotheses in a way that powers the RP, if it makes it more realistic with respect to new observations, and increases the empirical content of the set of explanations, the whole RP is defined as “progressive”. If the RP loses empirical content, accumulates anomalies and ad-hoc hypotheses, needs continuous emendations, the heuristic is in crisis and the RP is defined as “regressive”. Such a regressive RP will be sooner or later substituted by a rival RP, with a different explanatory core, able to cover all the empirical content of the previous RP. The ultimate refusal of a RP, like its initial foundation, is a free, operative, fallible choice of the scientists. By principle, any attempt of extreme defense of a RP is legitimate, as long as it respects the criteria of a critical rationalism and the adherence to evidences, like a nucleus of standards of evaluation adopted by the scientific community. In front of an anomaly, the scientist pins the blame initially on a marginal part of the protective belt (or on some initial conditions, parameters, auxiliary assumptions), protecting the core as long as possible (like in the case of the Darwinian ad-hoc hypothesis concerning the imperfection of the geological record, in this way protecting the gradualist assumption involved in the core-mechanism of natural selection). This defensive strategy could be successful: the anomaly is solved, the heuristic is reliable, the empirical content grows. Or provisionally successful: the patch apparently works, but it is weakening the protective belt. Or clearly unsuccessful, showing a pseudo-scientific attachment to non refutable and useless ad hoc hypotheses. Avoiding both a strict and a-historical fallibilism and by the way any methodological anarchism or external subjectivism or radical change of paradigms, the methodology of RP provides a possible rational criterion for understanding the continuous growth of knowledge in a field of researches, in order to compare the explanatory power of rival RPs, and evaluate the state of health of a long time dominant RP as well. The shifts of RPs could be rationally evaluated: if the modification of one or more auxiliary hypotheses – with the aim to restore the matching between the core and reluctant empirical evidences – has turned out to be a new version of the RP, supported by new facts, by an additional corroborated empirical content and by more successful predictions, then the shift of the RP has been “progressive” (that is, we have had a growth of knowledge). On the contrary, if any modification of a previous version of the RP has only the aim of “saving the phenomena” and generates a new theoretical system not

220

T. Pievani

supported by more independent evidences, then the shift is “regressive” and the RP is facing a crisis. When a RP accumulates anomalies and is no longer able to accommodate itself in a succession of models and theories that increase the empirical content, the scientists should decide to abandon it and move to an alternative frame, shifting the RS toward a new version (with a different theoretical structure, even if compatible with the previous core) or choosing a rival RP already available in the field. This decision is itself risky and subjected to falsification, depending on the experimental results of the new RP.

4 The Progressive Shift Between MS (ERP1) and ES (ERP2) What is the case of MS and ES in such dynamics? Using the methodology of RP, we could say that: • The core of the Evolutionary Modern Synthesis seems to have acquired today a defined dimension, as long as we consider its boundaries not too much immutable and impervious to change [47, 49]; • There is no alternative approach able to catch the continuous dynamics of change inside the evolutionary research programme, its meaning and its internal debates; • There is no evidence of a possible substitution of a dominant RP with a rival one, with a radical refusal of a whole previous tradition of researches, but there is in the field the typical scenario of a nonstop succession of shifts, extensions and revisions of the contemporary Neo-Darwinian RP. Furthermore, we know that MS has never been a monolith, but a meeting of languages, disciplines and tradition of researches: at least the tradition of population geneticists and that of naturalists, with respectively micro-evolutionary and macro-evolutionary perspectives. Nevertheless, MS tended to crystallize its “consensus” around some rigid methodological principles, intended as operationally no more under falsification (as it is usual in any RP according to Lakatos), like phyletic gradualism and genetic extrapolationism, defending a version of the RP based on a gene-centered and pan-selectionist view [12]. The contemporary followers of this ultra-Darwinian interpretation of the RP, with a great success in popularization, have even more oversimplified the core in a rhetorical fashion, speaking about an alleged universal Darwinian algorithm based on the “research and development” activities of the supreme engineer, the natural selection. But it is interesting to note the gap between this standard and popular view of evolution and the diversified reality of the experimental field, monitored in the major International publications. If we want a realistic epistemological representation of what is going on in the field, we should recognize a “received view” of the RP, in these terms: • The core of the RP named MS is the Neo-Darwinism as the genetic theory of natural selection;


221

• The protective belt is made by three major methodological postulates: phyletic gradualism; extrapolationism from microevolution; and strict functionalism or adaptationism; so we have a prevalence of assumptions of negligibility (strong in the cases of embryology, ecology and paleontology) and heuristic assumptions (like in the case of the underestimation of structural internal factors in evolution); • The deriving positive and negative heuristic is based on the programmatic idea of a universal, basic Darwinian logics, able for decades to gather a huge amount of new facts and prediction, with more and more sophisticated mathematical models. The MS so conceived shows also weak assumptions of domain in the belt (the application of the theory is supposed to be large, and widely extra-biological): the most important extensions of evolutionary models outside the strictly biological territory come from the application of this oversimplified version of the RP (like in the case of the strongly adaptationist approach in early evolutionary psychology – [4, 11]). But the claims of extended applicability clash with the growing difficulty to absorb in this standard frame the reluctant lines of researches above mentioned. So, the structure of the forthcoming theory of evolution could be represented as a profound and substantial reformation of this RP, without the substitution with another, but with a progressive shift. In other words, we have at the same time a serious conceptual novelty (the global structure of the RP changes because of discoveries not predictable by the previous programme) and a compatibility in the core with the previous RP [54, 60]. It is neither a superficial maquillage on marginal points of a hardened structure, nor a radical break with complete substitution of RP: rather, a steady and irreversible transformation of the architecture of the previous RP. Particularly, the lines of the reformation seem to be two: • An extension of the central Neo-Darwinian core, through theoretical and experimental updating, with in some cases the unexpected reversion to some “pluralistic” insights of Charles Darwin himself; • A quite complete substitution of the protective belt, from methodological monofactorial postulates to multi-factorial postulates and integrations of patterns. This transition has “progressive” features and could represent the passage from MS (the Evolutionary Research Programme 1 – ERP1) to ES (the Evolutionary Research Programme 2 – ERP2).

4.1

An Extended Neo-Darwinian Core

In this epistemological hypothesis, we see in detail that the core of the ES is today an “extended Darwinism”, with two interacting “hierarchies” of nested levels: a genealogical hierarchy of nested levels of transmission of genetic materials (organisms, populations like “demes”, species, monophyletic taxa); an ecological

222

T. Pievani

hierarchy of nested levels of transfers of matter and energy (organisms, populations like “avatars”, local ecosystems, regional ecosystems) [14]. The extended core includes: (A) The descriptive domain of evolution intended as factual evidence, that is the common descent with modifications, the postulate of the continuity of any evolutionary change, the phylogenetic unit of all living beings, the role of organisms as basic units of evolution. (B) The explanatory domain of plural, integrated “patterns” of evolutionary change (we use the term patterns instead of “models”, because the semantic view, with its emphasis on families of models as formal description of scientific theorizing, is clearly inadequate for the evolutionary RP, where models are useful tools in some fields but not the primary entities of the structure of the theory itself – [10, 17]); defining “patterns” the repeated schemes (epistemological and ontological) of historical real events, emerging from scientific observations, sufficiently general to be considered as “law-like” regularities in evolution [13], we see specifically: (B1) Variational patterns: multiple sources of non directed, inheritable variation, genetic and epigenetic, included the possible inheritance of ecological niches; the material basis for evolution and for natural selection is going to be diversified; (B2) Selective patterns: Darwinian natural selection and sexual selection, artificial selection, kin selection, in some cases group selection [58], briefly multilevel selection [41]; included here all the trade-offs between these selective processes, and peculiar competitive patterns like meiotic drive and spermatic competitions; (B3) Neutralist patterns: the non adaptive domain of the extended core, with three main sub-patterns: genetic drifts; nearly-neutralist mechanisms in the genomes, re-assortments and systemic mutations; non selective structural effects due to genetic constraints (genetic webs, limits to variation), developmental constraints (Evo-Devo), and physical-chemical constraints (self-organization); (B4) Macro-evolutionary patterns: the ecological side of the evolutionary hierarchy, with all the external, influential macro-evolutionary factors, able to produce repeated schemes of events like, in a decreasing order of impact on biological populations: mass extinctions; turnover pulses of species; rapid adaptive radiations; major evolutionary transitions due to processes of symbio-genesis [13, 49]. According to this kind of pluralistic core in ERP2, the evolutionary explanation becomes a way to integrate, case by case, different “patterns”, irreducible one to another, but compatible one with another, and all needed to cover the heterogeneous empirical basis of evolutionary phenomena. The ecological hierarchy


223

perturbs at different degrees the genealogical one, and the genealogical one accumulates changes and produces diversity. This multiple core (and the superpattern of the relationships between the ecological and the genealogical levels of evolution) is a candidate framework for the theoretical “unification” of evolutionary biology [14]. The first patterns (excluded epigenetic inheritance in modern sense), the second ones (excluded kin selection) and the structural ones are already Darwinian in their first formulations. The other ones are not originally Darwinian but compatible and integrative. This is an integrated framework where genealogical levels and ecological levels coexist and interact, but the Darwinian unit, the organism (at the same time, genetic replicator and ecologic interactor), and the Darwinian mechanism, natural selection (as differential survival and reproduction), remain the fundamental junction of the two hierarchies of levels of change (see the “sloshing bucket” model of evolution, in [14]). In this epistemological frame, we clearly understand the dynamics of assimilation and accommodation, and the mix of points of breaking and point of continuity, in the theoretical challenges above mentioned of Punctuated Equilibria and Neutralism. As restriction of validity, these patterns of the core of ERP2 keep their explanatory power in natural history until ca. 600 million years ago, that is the explosive beginnings of organized and individualized Metazoans. For earlier eras, the patterns could be intended as corroborated explanatory hypotheses, waiting for more information about the environmental conditions and the kinds of organisms involved. This theoretical nucleus represents also an interesting way to depict the uniqueness of the nature of explanation in evolutionary fields. The probabilistic generalizations and correlations of evolutionary biology have causal explanations that do not depend exclusively on the context of the scientific questions (like in some recent forms of relativistic “contextualism”), but reveal a deeper ecologicalgenealogical structure founded on the complementarity of three kinds of explanations. The explanandum of the theory of evolution is variational (the diversity of species and variants on Earth, their genealogical relationships, their transformations) and adaptive (any trait contributing to fitness, the complexity of structures and behaviors). The architecture of types of explanations is built on three pillars: (1) functional and selective explanations of the remote causes of emergence of a trait; (2) structural explanations of the relevance of internal constraints, and their trade-offs with external pressures; (3) historical and contingent explanations of chains of causal singular events, and clashes of independent chains of causes, a priori unpredictable but intelligible a posteriori. Starting from these three typologies, we can construct a matrix of relationships between the kinds of explanations: 1 + 2 in the cases of exaptations and trade-off between functions and structures, analogies and homologies; 1 + 3 in the cases of interferences between natural selection and Neutralistic processes and macro-evolutionary processes; 2 + 3 when Neutralistic processes create structural constraints; 1 + 2 + 3 when we need “total evidence” reconstructions of evolutionary pathways.

224

4.2

T. Pievani

A Pluralistic Protective Belt

Secondly, the protective belt of the RP becomes more and more pluralistic and flexible, with a robust diversification of models concerning the rhythms, the units, the levels and modes of evolution. Particularly: • A plurality of rates of evolution and speciation: gradual trends, stasis, punctuations, plural modes of speciation and changing relative frequencies [13]; • A plurality of units of evolution: group selection; multilevel selection; niche construction, endo-symbiosis and units organism-niche [41]; where the selection acts (genomes, organisms, developmental systems, organisms plus niches) and how (trade-offs between competition and cooperation); • A plurality of adaptive dynamics and interactions between structures and functions: frequency of exaptations in natural history; Evo-Devo; modularity; • A complexity of relationships between levels of evolution: phenotypic plasticity; evolvability. In the methodology of RP, the protective belt is subjected to continuous modifications due to the updating of evidences in surrounding conditions. The equilibrium between the weights of explanatory power in different patterns is instable. But what is crucial is that a refutation in the belt, or a radical change in the perspective of specific debate, does not mean necessarily a problem for the structure of the core. The belt is the magmatic, ever-changing, constantly refutable zone of the RP, exposed to external influences and contingencies of the researches. It could be also possible that an auxiliary pattern in the belt becomes so important and so diffuse in current evolutionary explanations that it deserves to be part of the core itself. In absence of strong contrary evidences, and having a good theoretical stability, it becomes part of the core, like in the case of genetic drifts and Neutralistic phenomena. So we have an extension of the core, always submitted to the falsification logics: if you have more patterns in the nucleus, a rival RP has more possibilities to reach a refutation of some assumptions or to outline a contradiction between explanations. For that reason, a RP should be not too much minimal and not too much extended, preserving its structural coherence and avoiding inappropriate extensions of the explanandum. In the passage between ERP1 and ERP2 the heuristic has changed its sign, being driven now by a programmatic pluralism, in definitions (like “species” and “gene”) and in explanations (with frequencies of integrated patterns), able to predict a lot of new facts in several evolutionary disciplines. We observe in literature that the new heuristic satisfies the criteria of “progressivity”. The assumptions of negligibility become less influent and the heuristic assumptions highlight the necessity of the integrations of factors. Conversely, the assumptions of domain and applicability become more stringent, stressing the opportunity to tune possibly other RPs for specific adjacent fields (like the evolution of culture – [6, 56]).


225

5 The Multiple Advantages of the Current Neo-Darwinian Pluralism The change of sign in the heuristic of ERP2 carries a more general epistemological transition. The standards of evaluation of hypotheses and theories are changing: the proofs through convergence and consilience of data become more and more important; we see the birth of originally interdisciplinary lines of researches; functions, structures and singular histories, mixed together, recover the original pluralism of the evolutionary explanations. A new theoretical challenge (as it was the Punctuated Equilibria theory, with its early “revolutionary” phase and later considerations and pondering about its real theoretical impact) is not necessarily concerning a marginal epiphenomenon surrounding a monolithic paradigm or on the contrary a radical crisis of its core. Otherwise, it could mean a profound extension and revision of its structure, remaining nevertheless compatible with other components and patterns of it [59]. The result is a structure of the theory of evolution, intended as a RP, more articulated in a pluralistic frame, more realistic in its assumptions about the currently available evidences [19, 50], with drastic revision of previous restrictive concept (regarding the “universality” of some patterns) hardened in the protective belt of ERP1 (or MS). The same case could be traced in the history of the idea of “functional cooptation” in Darwin, then “pre-adaptation” in Ernst Mayr and MS, then in the more radical sense of “exaptation” [22, 61] and “spandrels” by structural nonaptations [21]. It is clear in current literature that we do not need a conflation between standard adaptations and exaptations, but an “extended taxonomy of fitness” [20] made by three typologies of processes: classical Darwinian adaptations by natural selection; the functional shift, by natural selection, from a previous function to a secondary one; spandrels and other side effects with no adaptive reasons in their beginning, possibly co-opted by natural selection in new external conditions [46]. Also in this case we have points of breaking with ERP1 (not always the current utility corresponds to the historical origin) and points of continuity (natural selection acts, but finding trade-offs with internal constraints of organisms). So the advantage is double. Firstly, through these epistemological processes of assimilation and accommodation, we can better appreciate the conceptual tools involved in the most promising lines of evolutionary research today: for an excellent case, mixing genes, developments and ecological conditions, and considering all the patterns of evolution (mutations, natural selection, drifts, migration, hybridization, speciation), see [23]. Secondly, we can understand why one of the most important scientists involved in the developmental evolutionary biology, Alessandro Minelli, being conscious of the huge theoretical impact of Evo-Devo on ERP1 – in terms of conservation of genes families, developmental constraints, limits to variation, modularity of change, multiple effects, evolvability – nevertheless wrote that clearly Evo-Devo “does not offer a significant challenge to the NeoDarwinian paradigm” [35]. Evo-Devo likewise extends the conceptual frame of

226

T. Pievani

Neo-Darwinism and rectifies some previous interpretations (like gene-centrism and adaptationism) in its surrounding assumptions. The structure of ERP is evolving towards a more pluralistic version [1]. Furthermore, not less important, this Neo-Lakatosian approach offers some precious advantages in public debates (frequently hot) concerning evolution and its debates. The fact that in some points Darwin was wrong, of course, and MS was inadequate loses a great part of its striking dramatic power. Any RP is an evolving system, made by patterns, concepts, models, hypotheses, structured in a core (what is crucial for the survival of the RP) and a protective belt (where nothing is crucial for the fate of the RP). So a single refutation and an internal contradiction are not necessarily the end of the world for the theory of evolution, and we need to see the whole architecture of the RP and how it is rationally changing. A RP is never falsified by a single observation or anomaly, it could be defeated by a set of new evidences, new theories, organized in a rival RP [30]. The dynamics of criticism and growth of knowledge is continuous and rational, with a verifiable internal logics of proofs and refutations, so all the debate around the alleged “dogmatism” of the “Darwinians” appears like a non sense [48]. Every aspect of the evolution of ERP is under control and under potential falsification, even if some parts of the core (the descriptive domain and the major patterns of the explanatory domain, above described) are so much corroborated that they appear just like plain evidences without any reasonable doubt [7]. For the same reasons, we can solve another debate concerning the alleged scenarios “beyond Darwin”, or the supposed ultimate crisis of Neo-Darwinism: the challenges (frequently interesting by themselves) evocated as proofs of the imminent death of the “theory” are quite always debates concerning the protective belt of the RP. So, nothing ultimate, and moreover criticisms without a rival RP. But mostly, the methodology here exposed is very useful in the definition of what is the burden of proof in these debates. If someone wants to demonstrate that “another theory of evolution” is on the field (like in all the cases in which someone says that now there would be more “theories of evolution”), he has to prove that: (1) there is a rival ERP able to explain all the empirical basis of the current one; (2) this ERP is able to explain something more (it has an additional empirical content, predictions of new facts, on the basis of other corroborated facts); and it is able to do 1 and 2 using patterns, concepts and principles not reducible to those of the current one. It is a scheme of rational evaluation (and sophisticated falsificationism) clear and very fruitful for comparisons between ERPs. Only if we see these three conditions we can say that a rival RP has defeated a previously dominant one. We should grant anyone the benefit of doubt, even if the challenge seems to have nothing to do with science, but of course there is nothing like that rival RP in the field at the moment. These and other cases show how the application of the methodology of ERP could not only represent the ongoing transition between MS and ES very well, but could also offer valid arguments and epistemological tools of rational analysis in the never-ending debates that enliven, inside and outside the scientific community, the developments of the Neo-Darwinian research programme.


227

References 1. Ayala FJ, Arp R (2010) Contemporary debates in philosophy of biology. Wiley-Blackwell, New York 2. Boncinelli E (2009) Perche´ non possiamo non dirci darwinisti. Rizzoli, Milano 3. Bowler PJ (1983) Evolution. The history o fan idea. University of California Press, Berkeley/ Los Angeles 4. Buller DJ (2005) Adapting minds. MIT Press, Cambridge, MA 5. Carroll SB (2005) Endless forms most beautiful. Baror Int, New York 6. Cavalli Sforza LL, Feldman MW (1981) Cultural transmission and evolution. Princeton University Press, Princeton 7. Coyne JA (2009) Why evolution is true. Viking, New York 8. Coyne JA, Orr A (2004) Speciation. Sinauer Associates, Sunderland 9. Darwin C (1836–1844) Charles Darwin’s Notebooks 1836–1844. Ed. by: Barrett PH, Gautrey PJ, Herbert S, Kohn D, Smith S. Cornell University Press, Ithaca 10. Downes SM (1992) The importance of models in theorizing: a deflationary semantic view. In: Proceedings of the philosophy of science Association (PSA), vol 1-1992. The University of Chicago Press, Chicago, pp 142–153 11. Dupre´ J (2001) Human nature and the limits of science. Oxford University Press, Oxford 12. Eldredge N (1995) Reinventing Darwin. Wiley, New York 13. Eldredge N (1999) The pattern of evolution. W.H. Freeman, New York 14. Eldredge N (2008) Hierarchies and the sloshing bucket: toward the unification of evolutionary biology. Evol Educ Outreach 1:10–15 15. Eldredge N, Gould SJ (1972) Punctuated equilibria: an alternative to phyletic gradualism. In: Schopf TJM (ed) Models in paleobiology. Freeman, San Francisco, pp 82–115 16. Eldredge N, Tattersall I (1982) The myths of human evolution. Columbia University Press, New York 17. Godfrey-Smith P (2006) The strategy of model-based science. Biol Philos 21(5):725–740 18. Gould SJ (1977) Ontogeny and phylogeny. Harvard University Press, Cambridge, MA 19. Gould SJ (1989) Wonderful life. Norton, New York 20. Gould SJ (2002) The structure of evolutionary theory. Harvard University Press, Cambridge, MA 21. Gould SJ, Lewontin RC (1979) The spandrels of San Marco and the Panglossian paradigm: a critique of the adaptationist programme. Proc R Soc Lond B 205:581–598 22. Gould SJ, Vrba E (1982) Exaptation, a missing term in the science of form. Paleobiology 8(1):4–15 23. Grant P, Grant R (2008) How and why species multiply. Princeton University Press, Princeton 24. Jablonka E, Lamb MJ (2005) Evolution in four dimensions. MIT Press, Cambridge, MA 25. Kauffman S (2000) Investigations. Oxford University Press, Oxford 26. Kimura M (1983) The neutral theory of molecular evolution. Cambridge University Press, Cambridge, UK 27. Kirschner MW, Gerhart JC (2005) The plausibility of life. Yale University Press, New Haven 28. Kuhn T (1962) The structure of scientific revolutions. University of Chicago Press, Chicago 29. Lakatos I (1978) The methodology of scientific research programmes. Philosophical papers, vol 1. Cambridge University Press, Cambridge, UK 30. Lakatos I, Musgrave A (eds) (1974) Criticism and the growth of knowledge. Cambridge University Press, Cambridge, UK 31. Mayr E (1982) The growth of biological thought. Harvard University Press, Cambridge, MA 32. Mayr E (1991) One long argument. Harvard University Press, Cambridge, MA 33. Mayr E (2004) What makes biology unique? Cambridge University Press, Cambridge, UK 34. Minelli A (2009) Forms of becoming. Princeton University Press, Princeton

228

T. Pievani

35. Minelli A (2010) Evolutionary developmental biology does not offer a significant challenge to the Neo-Darwinian paradigm. In: Ayala F, Arp R (eds) Contemporary debates in philosophy of biology. Wiley-Blackwell, Malden 36. Minelli A, Fusco G (eds) (2008) Evolving pathways. Key themes in evolutionary developmental biology. Cambridge University Press, Cambridge, UK 37. Motterlini M (2000) Lakatos. Scienza, matematica, storia. Il Saggiatore, Milano 38. Musgrave A (1981) Unreal assumptions. Kyklos 34(3):377–387 39. Musgrave A (1993) Common sense, science and scepticism. Cambridge University Press, Cambridge, UK 40. Odling-Smee J, Laland K, Feldman MW (2003) Niche construction. Princeton University Press, Princeton 41. Okasha S (2006) Evolution and the levels of selection. Oxford University Press, Oxford 42. Oyama S (1998) Evolution’s eye. Duke University Press, Durham 43. Oyama S, Griffiths PE, Gray RD (eds) (2001) Cycles of contingency. MIT Press, Cambridge, MA 44. Pagel M, Venditti C, Meade A (2006) Large punctuational contribution of speciation to evolutionary divergence at the molecular level. Science 314:119–121 45. Pievani T (2002) Homo sapiens e altre catastrofi. Meltemi, Roma 46. Pievani T (2003) Rhapsodic evolution: essay on exaptation and evolutionary pluralism. World Future 59:63–81 47. Pievani T (2005) Introduzione alla filosofia della biologia. Laterza, Roma-Bari 48. Pievani T (2009) The world after Charles R. Darwin: continuity, unity in diversity, contingency. Rend Fis Acc Lincei, Springer 20:355–361 49. Pievani T (2010) La teoria dell’evoluzione. Il Mulino, Bologna 50. Pievani T (2011) Born to cooperate? Altruism as exaptation, and the evolution of human sociality. In: Sussman RW, Cloninger CR (eds) Origins of cooperation and altruism. Springer, New York (in press) 51. Pigliucci M (2001) Phenotypic plasticity: beyond nature and culture. Johns Hopkins University Press, Baltimore 52. Pigliucci M (2008) Is evolvability evolving? Nature 9:75–82 53. Pigliucci M (2010) Biology’s last paradigm shift: the transition from natural theology to Darwinism. Paradigmi (in press) 54. Pigliucci M, Kaplan J (2006) Making sense of evolution. University of Chicago Press, Chicago 55. Pigliucci M, M€uller GB (eds) (2010) Evolution – the extended synthesis. MIT Press, Cambridge, MA 56. Richerson PJ, Boyd R (2005) Not by genes alone. University of Chicago Press, Chicago 57. Sober E (2008) Evidence and evolution. The logic behind science. Cambridge University Press, Cambridge, UK 58. Sober E, Wilson DS (1998) Unto others. Harvard University Press, Cambridge, MA 59. Somit A, Peterson SA (eds) (1992) The dynamics of evolution. Cornell University Press, Ithaca/London 60. Sterelny K, Griffiths PE (1999) Sex and death. University of Chicago Press, Chicago 61. Vrba E, Gould SJ (1986) The hierarchical expansion of sorting and selection: sorting and selection cannot be equated. Paleobiology 12(2):217–228 62. West-Eberhard MJ (2003) Developmental plasticity and evolution. Oxford University Press, Oxford

The Theory of Evolution and Its Impact

Mining and Its Impact on the Environment

Authoritarian Argentina: The Nationalist Movement, Its History and Its Impact

Psychoanalysis: Its Evolution and Development

The Evolution of Macroeconomic Theory and Policy

The Evolution of Macroeconomic Theory and Policy

Evolution and the Theory of Games

Evolution and the Theory of Games

The Evolution of Macroeconomic Theory and Policy

Evolution and the Theory of Games

The Taurobolium: Its Evolution and Terminology

Information Theory and Evolution

Information Theory and Evolution

Information Theory and Evolution

The Evolution of Adaptive Systems: The General Theory of Evolution

Understanding Pedagogy: And Its Impact on Learning

Staging the Olympics: The Event and Its Impact

Inequalities: Theory of majorization and its applications

Artillery: An Illustrated History of Its Impact (Weapons and Warfare)

Semigroup Theory and Evolution Equations

Bacteriophage Ecology: Population Growth, Evolution, and Impact of Bacterial Viruses

Inequalities: Theory of Majorization and Its Applications

Number theory and its history

Net Theory and Its Applications

Set Theory and its Applications

Language Evolution and Syntactic Theory

Human Diet: Its Origin and Evolution

Inequalities: theory of majorization and its applications

Inequalities: Theory of Majorization and Its Applications

Measure Theory and its Applications

Set theory and its logic

The Theory of Evolution and Its Impact

Mining and Its Impact on the Environment

Authoritarian Argentina: The Nationalist Movement, Its History and Its Impact

Psychoanalysis: Its Evolution and Development

The Evolution of Macroeconomic Theory and Policy

The Evolution of Macroeconomic Theory and Policy

Evolution and the Theory of Games

Evolution and the Theory of Games

The Evolution of Macroeconomic Theory and Policy

Evolution and the Theory of Games

The Taurobolium: Its Evolution and Terminology

Information Theory and Evolution

Information Theory and Evolution

Information Theory and Evolution

The Evolution of Adaptive Systems: The General Theory of Evolution

Understanding Pedagogy: And Its Impact on Learning

Staging the Olympics: The Event and Its Impact

Inequalities: Theory of majorization and its applications

Artillery: An Illustrated History of Its Impact (Weapons and Warfare)

Semigroup Theory and Evolution Equations

Bacteriophage Ecology: Population Growth, Evolution, and Impact of Bacterial Viruses

Inequalities: Theory of Majorization and Its Applications

Number theory and its history

Net Theory and Its Applications

Set Theory and its Applications

Language Evolution and Syntactic Theory

Human Diet: Its Origin and Evolution

Inequalities: theory of majorization and its applications

Inequalities: Theory of Majorization and Its Applications

Measure Theory and its Applications

Set theory and its logic

Recommend Documents