Food and Evolution: Toward a Theory of Human Food Habits

FOOD AND EVOLUTION Toward a Theory of Hllman Food Habits

AND EVOLUTION Toward a Theory of Human Food Habits EDITED BY MAR'VIN HARRIS AND ERIC B. ROSS

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TEMPLE UNIVERSITY PRESS Philadelphia

Temple University Press, Philadelphia 19122 Copyright © 1987 by Temple University. All rights reserved Published 1987 Printed in the United States of America The paper used in this publication meets the minimum requirements of American National Standard for Information Sciences-Permanence of Paper for Printed Library Materials, ANSI 239.48-1984

Library of Congress Cataloging-in-Publication Data Food and evolution. Includes bibliographies and indexes. 1. Food habits. 2. Human evolution. 3. Nutrition-Social aspects. 4. Man, Primitive-Food. I. Harris, Marvin, 1927II. Ross, Eric B. [DNLM: 1. Food Habits. GT 2860 F686] GN407. F65 1986 306 86-5773 ISBN 0-87722-435-8 (alk. paper)

Although now substantially revised, the initial drafts of the papers in this volume were presented at the 94th Symposium of the Wenner-Gren Foundation for Anthropological Research at Cedar Key, Florida, October 23-30, 1983. On behalf of all the participants, the editors wish to thank the foundation and its staff for their support and advice. We were especially aware of our debts to Lita Osrnundsen, the foundation's director of research. The editors are also deeply grateful to the staff of Temple University Press, especially to Jane Cullen, Jennifer French, and Jane Barry for their heroic production and copyediting feats.

1

Introduction Part I. Theoretical Overview 1. An Overview of Trends in Dietary Vlriation from Hunter-Gatherer to Modern Capitalist Societies ERIC B. ROSS

7

2. Foodways: Historical Overview and Theoretical Prolegomenon MARVIN HARRIS

57

Part II. Bioevolutionary Antecedents and Constraints 3. Primate Diets and Gut Morphology: Implications for Hominid Evolution KATHi\RINE MILTON

93

4. Omnivorous Primate Diets and Human Overconsumption of Meat WILLIAM]. HAMILTON III

117

5. Fava Bean Consumption: A Case for the CoEvolution of Genes and Culture SOL()MON H. KATZ

133

Part III. Nutritional and Biopsychological Constraints 6. Problems and Pitfalls in the Assessment of Human P. L. PELLETT Nutritional Status

163

7. Psychobiological Perspectives on Food Preferences and Avoidances PAUL ROZIN

181

8. The Preference for Animal Protein and f'at: A Cross-Cultural Survey H. LEOr~ ABRAMS, JR.

207

Vll

Contents

9. Biocultural Consequences of Animals Versus Plants as Sources of Fats, Proteins, and Other Nutrients LESLIE SUE LIEBERMAN

225

Part IV. Pre-State Foodways: Past and Present

10. The Significance of Long-Term Changes in Human Diet and Food Economy

261

MARK N. COHEN

11. Life in the "Garden of Eden": Causes and

285

Consequences of the Adoption of Marine Diets by Human Societies DAVID R. YESNER

12. The Analysis of Hunter-Gatherer Diets: Stalking an

311

Optimal Foraging Model BRUCE WINTERHALDER

13. How Much Food Do Foragers Need?

341

KRISTEN HAWKES

14. Aboriginal Subsistence in a Tropical Rain Forest

357

Environment: Food Procurement, Cannibalism, and Population Regulation in Northeastern Australia DAVID R. HARRIS

15. Ecological and Structural Influences on the

387

Proportions of Wild Foods in the Diets of Two Machiguenga Communities ALLEN JOHNSON and MICHAEL BAKSH

407

16. Limiting Factors in Amazonian Ecology KENNETH R. GOOD Part V. The Political Economy and the Political Ecology of Contemporary Foodways

427

17. Loaves and Fishes in Bangladesh SHIRLEY LINDENBAUM

18. Animal Protein Consumption and the Sacred Cow Complex in India

VIn

K. N. NAIR

445

Contents

19. The Effects of Colonialism and Neocolonialism on the Gastronomic Patterns of the Third 'Vorld RICHARD W. FRANKE

455

20. Stability and Change in Highland Andean Dietary Patterns BENjAlvlIN S. ORLOVE

481

21. Social Class and Diet in Contemporary Mexico GRI~TEL H. PELTO

517

22. From Costa Rican Pasture to North American Hamburger Mi\RC EDELMAN

541

Part VI. Discussion and Conclusions 565

23. The Evolution of Human Subsistence ANl'~A

ROOSEVELT

24. Biocultural Aspects of Food Choice GEORGE ARMELAGOS Mterword About the Contributors Glossary Name Index Subject Index

579

595 601 607 613 625

IX

THIS BOOK RESULTS FROM AN INTER_DISCIPLINARY EFFORT TO ADvance our understanding of why human beings in differing times and places eat what they do. It begins, at the most fundamental level, with the collective view of the editors and other contributors that knowledge and comprehension of human foodways, and the web of practices and beliefs associated with them, must depend upon our seeking general principles and recurrent processes beneath the immediate appearance of a worldwide confusion of seemingly capricious preferences, avoidances, and aversions. Once this decision is made, however, a complex set of explanatory strategies and options still remains to be explored and integrated, since the knowledge we have of human food customs and practices derives from data collection that has traditionally been dispersed among varied specialties and theoretical strategies. We cannot claim that all the relevant disciplines or all the salient levels of analysis and perspective are represented in the chapters that follow, nor do we presume that this work encompasses an adequate representation of those that are. But we hope at least to have helped to broaden the general scope of inquiry beyond the horizons of any single viewpoint, while still maintaining what we emphatically regard as a commitment to a nomothetic approach. The disciplinary perspectives of the contlibutors to this volume range over primatology (Hamilton, Milton), nutrition (Pellett, Lieberman), biological anthropology (Armelagos, Katz), archaeology (Yesner, Cohen, Roosevelt, D. Harris), psychology (Rozin), and agricultural economics (Nair). Although cultural anthropologists predominate numerically, they too offer a great diversity of insight and information based on their varying professional interests and, in particular, their wide spectrum of regional specializations: Bangladesh (Lindenbaum), Amazonia (Johnson and Baksh, Good, Ross), Paraguay (Hawkes), Canadian sub-arctic (Winterhalder), Southeast Asia and Africa (Franke), Mexico (Pelto), Costa Rica (Edelman), Peru (Orlove), and Europe (Ross). In attempting to integrate the diversity of disciplinary viewpoints that these scholars represent, the editors chose an evolutionary framework as the only suitably broad yet coherent and unifying one available to us. In its biological dimensions, at least, it seemed self-evident that the core of human dietary practice, all subsequent embellishment aside, must be regarded in terms of the

1

Introduction

emergence of the hominidae and the co-evolution of human diet and our physical potential for cultural behavior. It seems likely, for example, that hunting for vertebrates, increased meat consumption, and expanded tool use were implicated in the evolutionary processes that led to the expansion and reorganization of the australopithecine brain and to the development of Homo's unique capacities for consciousness and semantic universality. There is, at least, little doubt that, throughout most of the Pleistocene, the evolution of biological repertoires and the evolution of behavioral repertoires were closely intertwinedand that diet is one domain where the intersection was particularly noteworthy. With the appearance of Homo sapiens, if not earlier, however, a progressively greater independence-or lag-between biological and cultural selection reduced the rate and incidence of gene-culture co-evolution. Radically different modes of production, accompanied by massive changes in food habits, emerged in the later phases of human prehistory and throughout subsequent history without any discernible evidence of related changes in gene frequencies. Increasingly, behavior associated with the procurement, distribution, and consumption of food came, like the rest of human behavior, to be propagated through learning rather than genetic replication. And although selection based on consequences for reproductive success continued to operate, it was increasingly supplemented, if not displaced, by selection based on the more immediate consequences for the satisfaction of biopsychological needs and drives. Though the feedback between these two levels of selection became increasingly indirect and delayed, the biological level still cannot be excluded from our attempt to understand general as well as particular aspects of the evolution of foodways. Indeed, in a small number of cases such as that of fava bean (see Chapter 5) and milk consumption, specific preferences and avoidances continue to be associated with genetic polymorphisms found with varying frequencies among different populations. In evolutionary perspective, however, most of the great changes in human diet can be more readily associated with shifts in modes of production that are not in tum linked to such genetic variations. The transition from upper paleolithic to neolithic modes of production, for example, generally involved a shift from narrow reliance on animal foods to broad-spectrum regimens in which the consumption of domesticated tubers and grains gained ascendancy over meat and other animal foods (pastoral modes of production, of course, followed a divergent trajectory). The next great general evolutionary changes in foodways may be associated with the rise of archaic agro-managerial states whose dense, socially stratified populations were dependent on one or two staple grains and which maintained distinctive consumption patterns for elites and commoners. The further evolution of imperial state systems with massive potentials for trade and great capacities for modifying their habitats through public works doubtless increased such class or caste distinctions in dietary practice and gave

2

Introduction

rise to new rural/urban and core/periphery distinctions. These effects of political-economic evolution and of ever more formidable political-ecological integration finally attained global proportions with the emergence of the capitalist world system, leading in our own times to a return to highly carnivorous diets for privileged regions and classes at the cost of impoverished diets and often de facto vegetarianism in dependent and underdeveloped areas. The contributions to this volume have been arranged with these broad evolutionary considerations in mind. Following the editors' theoretical overviews, Parts II and III deal with the biological, nutritional, and psychological factors that reflect species-specific and/or population-specific consequences of human genetic repertoires. Part IV deals with food patterns associated with pre-state sociocultural systems as revealed through both archaeological and ethnographic researches. And Part V concerns itself with foodways in contemporary state-level societies, with emphasis upon the consequences of underdevelopment and participation in the capitalist world system. Needless to say, it is impossible for any single volume to provide a thoroughly comprehensive treatment of so conlplex a subject as the evolution of human food habits or to reach any definitive theoretical outcome. What we have hoped to do, however, is to provide a guide and a framework for much needed future investigation, and an incentive for others to join in that necessarily collaborative enterprise. M. H. and E. B. R.

3

Theoretical Overvie"T THE TWO ESSAYS THAT FOLLOW SHARE AN EXPLICIT MATErialist strategy and are addressed specijically to the question of the general determinants offood preferences and avoidances. They range over a variety ofpre-state and state-level foodways, highlighting food t'ractices that have generally been regarded as beyond the pale of nomothetic approaches or whose cost-benefit signijicance is in dispute. The epistemological basis for distinguishing idealist from materialist approaches to foodways rests on the separation of data obtained through emic operations from those obtained through etic operations. Emic foodways data result from eliciting operations in which the participants' sense of what people eat or ought to eat, and the symbolic signijicance of food preferences and avoidances, dominate data collection. On the other hand, etic foodways data do not necessarily require eliciting operations and are reported in a data language whose units and categories are imposed by the observers (e.g., calories, proteins, costs and benefits). Beyond the separation of emics from etics, materialist approaches to foodways start with the assumption that puzzling dietary habits are the outcome ofdeterminative processes in which biopsych0 logical, technological, economic, demographic, and environmental factors predominate. These infrastructural processes account for the evolution of distinctive forms ofstructures and superstructures. Once such structures (e.g., domestic and political organization) and superstructures (e.g., religious and symbolic systems, Philosophies, aesthetic standards) are in place, they ofcourse exert an influence over all aspects ofsociallzfe, includingfoodways. Religious food taboos, for example, have a distinctive role to play in the maintenance offood habits. But recognition that structural and superstructural features react back upon infrastructure does not lessen the distinction between materialist and idealist approaches or justify taking reful?e in an eclecticism that is incapable of weighing one causal component against another or of stating the conditions under which now infrastructure, now superstructure, achieves dominance. The restraints imposed by infrastructure upon structure and superstructure remain dominant in the determinative processes that lead to continuity or change in food-

5

1. Theoretical Overview

ways: foodways that acquire adverse etic cost-benefit balances will tend to be selected against; foodways that have favorable etic cost-benefit balances will tend to be selected for. Participants' emic valuations of foodways arise from infrastructure. Major changes in infrastructure cause major changes in foodways and their emic valuations. Changes in emic valuations change major foodways, but only when such changes are favored by infrastructural conditions. As both essays stress, the balance of etic costs and benefits that provides the cultural and biopsychological selection pressures for and against particular foodways often differs markedly according to age- and sex-related status roles and social strata. Hierarchies based on sex, class, ethnicity, and other distinctions are usually associated with favorable cost/benefits for some status roles but unfavorable cost!benefits for others. Where such conditions prevail, the study of foodways must form part of the study ofpolitical economy and political ecology. As in contemporary state societies and their neocolonial dependencies, what people eat is often what they are allowed to eat or obliged to eat as a consequence of their subordination to the material priorities of ruling classes and corporate elites.

6

ERIC B. ROSS

An Overview of Tren_c/ //

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VITAMIN E MI TIGATES

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NOTE: This figure appeared in S. H. Katz and]. Schall, Favism and Malaria: A Model of Nutrition and Biocultural Evolution. In N. Etkin, ed., Plants Used in Indigenous Medicine and Dzet: Biobehavwral Approaches. New York: Redgrave Press, 1986. © 1986 by Redgrave Publishing Company. Reproduced here courtesy of Redgrave Press.

142

5. Fava Bean Consumption

R B C. These findings interrelating glucose metabolism, fava bean effects, vitamin E, the significance of malarial factors, and oxidant stress in the R B Care summarized in Figure 5.4. Furthermore, it is likely that the same oxidant stress occurs in normal, G 6 P D-sufficient cells, except that the stress is not great enough to allow permanent damage from hydrogen peroxide. However, we hypothesize that the combination of oxidant stress provided by consumption of fava beans and infection by the malarial plasmodium is sufficient to interrupt the normal development of the parasite. I presented this concept at the Center for Tropical Diseases in Jerusalem. Subsequent research (Golenser et al. 1983) was designed to determine in vitro the susceptibility of G6PD-deficient and normal erythrocytes incubated with and without isouramil, one of the principle pyrimidine oxidants of fava beans. The addition of isouramil decreased malarial parasite growth rates in G6PDdeficient cells, but not in normal cells. In parasitized erythrocytes, the addition of isouramil had direct anti-malarial effects in both normal and G D P D-deficient cells during the trophozioite and schizont parasite stages (Golenser et al. 1983). This evidence helps to confirm our hypothesis at the biochemical level. Furthermore, I propose that the anti-malarial effect of fava beans is sufficient to create the kind of equilibrium necessary to maintain a balanced presence of the genetic mechanism (G d B -) and a pattern of fava bean consumption in which both factors promote resistance to malarial infections. Additional evidence supporting this hypothesis is the fact that high-level depletion of vitamin E, which normally protects the R B C from the damaging effects of hydrogen peroxide, can result in protection against hemolysis in G d B - individuals (Spielberg et al., 1979). Alternatively, animal studies by Eaton and Eckman (1977) and human studies by Friedman (1978) concluded that vitamin E deficiency allows for a more rapid accumulation of damage to normal cells infected by malarial parasites and a lowering of overall infection rates by intercepting the plasmodial life cycle, presumably in much the same as was in the G6PD-deficient cell. Hence, it is likely that the consumption of fava beans lowers the GSH of GdB+ individuals sufficiently to have a net positive protective effect on their resistance to malaria.

Epidemiological Data We reasoned that if fava beans had some kind of anti-malarial effect on male hemizygous normals and female homo- and heterozygous individuals, then the fava bean should be widely distributed in association with the occurrence of the G d B - genotype and malaria. The evidence on the distribution of all three variables shows a remarkable concurrence among them, suggesting the likelihood of a significant interaction. Moreover, the available data on the season-

143

II. Bioevolutionary Antecedents and Constraints

ality of malaria and fava bean consumption in Egypt, Iran, Greece, and Italy (Belsey 1973; Katz, Adair, and Schall 1975) indicate a high degree of overlap between the peak season of consumption and the peak occurrence of the malarial vector (see Figure 5.5 and Katz and Schall 1979). Although these epidemiological data could reflect merely the coincidence between the climatic

FIGURE 5.5. Seasonal Variation in Malarial Vectors, Fava Bean Harvest, and Fava Consumption jan. Malana vector

I

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I

r

Fava consumptIOn

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Fava harvest Fava consumptIOn

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Malana vector

Fava consumptIOn

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Fava harvest

Dec. I

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Fava consumptIOn

Italy

Nov. I

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Fava harvest

Greece

Oct. I

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Malana vector

Iran

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Aug. sep.

Feb. Mar. Apr. May jun. jul. I

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c:.

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NOTE: The shaded areas refer to peak consumption periods for fava beans. The ragged lines separating the species of mosquito indicate overlapping seasonal life cycles for these vectors.

144

5. Fava Bean Consumption

TABLE 5.1. Comparative Nutritional Values for Mediterranean Region Legumes % Protein

Legumes

(dry weight)

Protein Efficiency Ratio a (cooked legumes) 2.05 ± 0.10

Chick peas

17.8

Lentils

24.0

1.14 ± 0.14

Kidney beans

22.5

1.51 ± 0.22

Fava beans

23.5

1.17 ± 0.17

aGrams protein consumed, divided by grams of weight gain, in rats. NOTE: Adapted from FAO Reports on the nutritional contents for legumes (Food and Agricultural Organization, Rome, 1959).

conditions conducive to the spread of malaria and those favoring the cultivation of fava beans, it is unlikely that such a coincidence would be distributed so widely and consistently over the region, particularly if the beans had only negative effects.

Nutritional and Agricultural Potential Although the epidemiological data show a clear association between the seasonal occurrence of malaria and the consumption of fava beans, this evidence is not conclusive, since the extensive distribution of the fava bean could be explained, for example, by its agricultural and nutritional advantages. In this context it is clear that fava beans are higWy suited to many of the environments in which they are grown. Likewise, their nutritional value is in the same range as that of other regionally grown pulses and legumes, which tend to be relatively high in lysine and low in tryptophan and the sulfur-containing amino acids. Hence, while clearly a higWy productive crop, their presence is not additionally explainable on the basis of any significant nutritional advantages over other pulses and legumes found in these regions. Moreover, these other regional legumes do not contain constituents that trigger hemolytic crises in G6PDdeficient individuals (Table 5.1 and Katz and Schall 1979).

Population Genetics In order to test the hypothesis that fava beans provide selective advantages for the nonnals of both sexes and heterozygous females and disadvantages for hemizygous deficient males, I carried out analyses of the available genetic data

145

II. Bioevolutionary Antecedents and Constraints

on population distributions of the GdB - genotype. The usefulness of these rather extensive data is limited by the difficulties in classifying female heterozygotes because of the deactivation of one of the X chromosomes during embryonic development, according to the Lyon hypothesis (Motulsky 1965). The data are also complicated by the fact that other genes for acid phosphatase B (Bottini et al. 1971), thalassemia in females (Carcassi 1974; Friedman 1978), and possibly tyrosinase variation (Beutler 1970) all play roles in mitigating the hemolytic effects of fava beans. Another factor that is likely to be important in the expression of GdB - in females is associated with the onset of adrenarche. Since adrenarche is associated with increased secretion of dehydroepiandrosterone (D H E A), which directly inhibits G 6 P D activity, it is highly likely that the unusual variation in the age at which favism is prevalent in females is closely associated with this developmental event, which occurs at age six to seven (Katz et al. 1983) and is particularly significant in children with higher body mass indexes (Katz et al. 1985). Since these interactions and other unknown factors tend to limit the data, it is more useful to compare the actual ranges of gene frequencies with various hyopthetical outcomes based upon variation in consumption patterns. If we assume that fava bean consumption confers no advantage, then we should see a trend that rapidly proceeds towards a very high frequency of the G6PD-deficiency gene; conversely, if there was a high selective advantage for the consumption of fava beans by normal individuals, the GdB - gene would merely disappear over time. However, if fava bean consumption was somewhat advantageous for the normals and slightly more advantageous for the heterozygotes, which would be the case if fava beans were not consistently available in areas of endemic malaria, then a balanced polymorphism could be maintained in the same range that is widely reported in the circum-Mediterranean region. Hence, the fact that the population genetic data tend to support a balanced genetic polymorphism suggests additional evidence in favor of an anti-malarial effect from fava bean consumption. A more detailed explanation of the population genetics of this phenomenon can be found in Katz and Schall (1986; see Figure 5.6).

The Evolution of Cultural Information I postulated that if fava beans were consumed over a long enough period of time, the cultural information about them would evolve toward an optimal fit with the cumulative biological effects of the beans. The model would predict a significant growth of cultural mechanisms to prevent the continued consumption of the beans if their net effects were negative. The accumulation of knowledge would proceed to the point where they would no longer be consumed, since danger of death and illness would be correlated with their consumption. On the other hand, if in addition to their negative hemolytic effects on G6PD-

146

5. Fava Bean Consumption

FIGURE 5.6. Selection Models: Favism, Malaria, and G6PD Deficiency, by Sex MALF MALARIA

MALARIA

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General Health

of Carbohydrate

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HOmOZygo~------ZS Norm,ls

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_

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I

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II

Heterolyqotes

i Lyonlzatlon ......I - - -

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~

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- -I

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1

plus

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NOTE: Males and females are separated to show the differences in selection for this sex-linked gene. The arrows refer to factors that theoretically increase (upward arrow) and decrease (downward arrow) the frequency of the C I G 6 P D Mediterranean gene.

deficient individuals, they had some benefit such as promoting "good health" (i. e., absence of disease due to malaria), we would expect to see a mixture of culturally evolved traditions, both prescriptive and proscriptive, governing the behavior surrounding their consumption. Before the cultural and historical evidence for the pattern of consumption can be evaluated, the time frame of these biocultural evolutionary hyoptheses has to be considered. Fava beans were one of the first plants to be intensively gathered by Indo-European populations. Probably coincident with or anteceding any kind of grain cultivation, they are found in association with neolithic pile

147

II. Bioevolutionary Antecedents and Constraints

dwelling sites in Switzerland and open-air sites in northern Italy, Spain, and Hungary. Even before their human use in Europe, fava beans were established in a range that extended from Persia and the Himalayas to the East and ultimately to the Atlantic coast in the West. There is other evidence of their use in Bronze age Troy and 12th-Dynasty Egypt, and there are many references to them in classical Greek and Roman literature (Andrews 1949; Arie 1959; Celsus 1935; Giles 1962; Herodotus 1947; Rowlett and Mori 1970). Currently they are known to extend through China and as far as Taiwan. Extensive archaeological and historical data allow for a more careful analysis of our hypothesis, since the period of their continuous cultivation and apparent consumption is so considerable. Given this time dimension, it seems likely that had the effects of fava beans been only negative, their use as a human food would have long since disappeared among populations with G 6 P D-deficiency. Yet it could be argued that no implicit or explicit knowledge ever evolved about their toxicity. This argument, as it applies to the mode of X-linked inheritance (Papavasiliou et al. 1972) of favism, has been made by Giles (1962), who hypothesized that the Indo-European kinship pattern of patrilineality and patrilocality at least tends to preclude the correlation of favism with maternal inheritance in males. That is, the females who carry this X-linked trait to their sons are continually separated out by exogamy from the lineage, which makes it difficult to correlate the illness with family lines. Thus, data about favism could also be used to test hypotheses concerning the ways in which knowledge spreads when knowledge of the disease is carried by women versus men. Presumably women would have observed that their brothers were susceptible to the disease. Therefore, if their sons had the same symptoms as their brothers, it is reasonable to suggest that the women would have drawn some conclusions about the disorder. This knowledge could have given rise to various beliefs and behaviors among women that were different from those of men. A careful investigation of historical data and the roles of women in the transmission of knowledge from one generation to the next under patrilineal, patrilocal, and a partial matrilateral cross-cousin marriage kinship system could yield fruitful tests of hypotheses concerning this aspect of the biocultural evolutionary process. Although favism as a specifically defined disease was first described in the mid-19th century, it is not clear whether it was known by other names or clusters of symptoms at the folk level. For example, through interviews I conducted in areas of Sardinia with very high rates of favism, I uncovered-contrary to the local medical belief-a well-founded folk knowledge of favism that extended back to the childhood of the oldest members of the community, some of whom were over 70. One distinctly recalled being warned about fava beans during childhood by his grandparents. This suggests that knowledge of the beans' negative effects went back well into the 19th century. Nevertheless, it is

148

5. Fava Bean Consumption

difficult to trace explicit knowledge before the 19th century, and this may also explain why favism was not directly correlated with fava consumption earlier. However, this does not rule out the possibility that earlier prescription or proscription of fava beans could evolve without any explicit knowledge of the relationship between bean consumption and favism. More recently, studies have been conducted to determine whether traditional cooking, processing, and other dietary activities significantly alter the toxicity of the bean for individuals with G6PD deficiency (Belsey 1973; Jamalian 1978; Jamalian, Aylward, and Hudson 1977). In other words, it is reasonable to suggest that certain appropriate processing techniques may have evolved to decrease the possibility of fatalities from favism. Since there are considerable variations in processing, only two of these pathways will be considered here. However, before considering processing per se, it is important to point out that many, but not all, populations tend to consume the beans raw without any processing. In the event of an impending fava crisis, it is reported that the folk medical treatment of Iran is a high "sweet" diet consisting of naturally occurring sweet foods. This is believed to reduce the significance of the crisis. Indeed, there may be some medical rationale for this prescription, since the increased availability of glucose to a G6PD-deficient individual may provide sufficient saturation with glucose-6-phosphate to optimize the remaining G6PD activity, which is involved in the production of NADPH and in tum maintains a necessary level of GSH (Katz and Schall 1986; Katz et al. 1978). The GSH in tum prevents the toxic build-up of cellular peroxides and thus lessens the probability of a fava-induced hemolytic crisis. The first step in processing fava beans is soaking. Most ethnic groups studied do soak their dried beans, and it is likely that soaking is sufficient to trigger the first reactions of germination. Although significant changes in the biochemical constituents could result from this germination process, little is known about its effects upon the toxicity of the beans, except that the toxic constituents are partially water soluble and would be discarded with the soaking water. It is known that the sprouting of soybeans, another legume, rapidly eliminates the anti-trypsin protein activity that prevents insect predation. Since the principal mechanism that the fava bean has evolved to protect its seed is the production of pyrimidines, it is likely that germination would produce a significant change in its oxidant activity. A second widely practiced step in processing consists of removing the skin of the bean. This has been studied by Jamalian and associates Oamalian 1978; Jamalian, Aylward, and Hudson 1977), who report high toxicity for all parts of fresh mature seeds, but higher activity in the seed coats than in the fresh seed flesh, although the overall toxicity was lower in the dried beans. Both major processing steps make a difference in the outcomes, and both are widely used. Jamalian and his associates Oamalian 1978; Jamalian, Aylward,

149

II. Bioevolutionary Antecedents and Constraints

and Hudson 1977) also report that the GSH levels of the processed beans were lowered by incubation, and that the level remaining was sufficient to avoid spontaneous hemolysis. This raises an important and as yet unanswered question: if the oxidant activity is lowered sufficiently to improve the survival of G6PD-deficient individuals, is it still sufficient to add any protection against malaria in the hemizygous males and homo- and heterozygous females? This question suggests that the model of the relations between fava bean consumption, favism, and the genetic factor requires a separate model for males and females, since males are hemizygous and either have or do not have the gene and the potential for the disease, whereas females have three classes of phenotypes, each with varying susceptibility. If the model also includes the potential interaction with malaria and the effects of fava bean consumption on the genetic frequency of the GdB - gene, then the model begins to take on the characteristics of a more formal quantitative model of genetic change. Elsewhere Katz and Schall (1986) have developed a heuristic model of this phenomenon, which is presented here as Figure 5.6.

Folklore and Fava Bean Consumption The fact that fava beans have had sufficient time to come to some kind of equilibrium with population groups strongly favors the accumulation of many specific beliefs about their effects. Consistent reports in the classical Greek, Roman, Egyptian, and Indian literature associate them with death (Andrews 1949). Andrews has conducted an intensive study of the ambivalence about fava beans. Although he was unable to conclude which factors besides the flatulence associated with fava bean consumption gave rise to the ambivalence of the belief that the beans were occupied by the souls of the dead, he determined that beliefs about the beans were not associated with some ancient vestige of Indo-European totemism, nor did they stem from some historical accident. The evidence he developed is extensive and relevant to the complex evolution of cultural knowledge about fava beans: The ancients felt toward beans a mingled respect and dread, a complex of emotions suggested by the Greek term lEQoa, which apparently was generally applied to an object believed to be charged with some supernatural force, contact with which might be either beneficial or harmful. Today we generally call this mysterious power mana in its helpful aspect and taboo in its harmful aspect. Beans belonged in the category of objects possessing both mana and taboo. (Andrews 1949: 277)

Such beliefs in tum led to the notion that fava beans had enormous generative power-a power to be avoided by those members of society whose social

150

5. Fava Bean Consumption

functions required avoidance of death and sought by those whose functions were closely associated with death. Andrews has also documented that the ambivalence and controversy surrounding the consumption of fava beans are both ancient and widespread. He was able to accumulate evidence from the Greco-Roman era, ancient Egypt, India, and 19th- and 20th-century Mrica. In addition, Rowlett and Mori (1970) have accumulated data for English folklore. These cultural data may be briefly summarized by area and time period. GREECE Despite the strong proscriptions against the beans in classical Greece, there is evidence of their continued use and consumption. The strictest aviodance of fava beans there appears to have been practiced by the Pythagoreans. Andrews relates that "the Pythagorean taboo was so stringent that it extended even to treading down the growing bean vine. According to one account . . . Pythagoras, pursued by Syracusan soldiers, could not bring himself to escape by crossing a field of beans, preferring to let himself be taken and killed. According to another. . . some Pythagoreans, fleeing from hostile soldiers, stopped when they came to a bean field in flower and defended themselves to the death" (1949:276). Bean avoidance extended to other elements of the Greek population as well, although no one at that time seems to have known why the custom existed. i\ristotle reported that the Pythagoreans, who were partisans of the oligarchical regime, detested the beans because they were used to cast a vote in elections for magistrates and were therefore a symbol of democracy. Nevertheless, Andrews notes that Aristotle supplied four more explanations for fava bean avoidance without settling on anyone of them. Plutarch also offered various explanations, as did Lydus. Arie (1959) hypothesizes that at the root of the Pythagorean aversion was Pythagoras's own G6PD deficiency and possibly some knowledge about favism. What is evident is that although many ancient Greeks continued to eat fava beans, others shunned them, and those that avoided them had a plethora of reasons for doing so. ROME Judging from such information as Andrews provides, the prevailing rationale for fava bean avoidance among the ancient Romans was that the beans caused bad dreams. For this reason, Pliny, Diogenes Laertius, and Amphiaraus, a mythical dream interpreter, suggested abstention (1949:285). Plutarch noted that consumption of the beans was associated with increased male sexuality, restlessness, dreams, and flatulence. At the same time, others (particularly physicians) felt that fava beans were a good, healthful food. They were popular with artisans, farmers, builders, and gladiators (1949:281n).

151

II. Bioevolutionary Antecedents and Constraints

ENGLAND Rowlett and Mori note the presence of "unmistakable references to the magical effects of fava beans-or at least their deleterious ones"-in English folklore (1970: 100). In many bean stories and superstitions, of course, it is nearly impossible to determine the identity of the bean or beans involved; but there are some stories in which the involvement of fava beans is quite beyond doubt. One of these is Ralph of Coggershall's tale of the Green Children, in which children eat beans, turn green (which is diagnostic of favism), and die. Similarly, the identification of fava beans in the Jack and the Beanstalk story is certain, as the beans in the story are very large and the stalk is tall and strong. Other folk conceptions concerning fava beans in England include the popular idea that more cases of lunacy occur when the plant is in bloom than at any other time of the year, a notion among coal miners that accidents in the pits occur more frequently when the bean plants are in bloom, and a general reluctance to have bean blossoms in the house. There is also a saying: "Sleep in a bean field all night if you want to have awful dreams or go crazy" (Rowlett and Mori 1970: 101), as well as the idea that eating fava beans can harm one's senses of smell and vision and can be harmful to the blood. Rowlett and Mori suggest that "some of the most persistent English folktales" deal principally with the effects of Vicia Java (ibid.). ANCIENT EGYPT Andrews (1949:277n) notes the existence of bean avoidance in Egypt, but it is not clear how extensive or stringent the taboo was. Herodotus states that Egyptians would neither grow these beans nor eat them raw or cooked, and that they were so strongly proscribed for the priests that they could not even tolerate the sight of them; yet archaeological evidence and papyrus records at least as far back as the 12th Dynasty suggest their widespread and long-term use as a food and in funerary rites. "There is no doubt," says Andrews, "that a taboo of some kind did exist, and various implausible explanations have been advanced" (ibid.). Here again, we seem to have a situation in which fava bean taboos and widespread fava bean consumption exist side by side in the same society. Currently, fava beans are a major staple food for the vast majority of the Egyptian population. INDIA Other evidence for fava bean avoidance comes from Vedic India and the ethnographic present: "A bean taboo imposed on those rendering sacrifice is mentioned in the oldest Indian ritualistic text, the Yajurveda, as well as in the

152

5. Fava Bean Consumption

Maitrayani Samhita and the Kathaka. The Bagdis of central and western Bengal are apparently of Dravidian descent. In the territory of Bankura, where the original caste structure seems to be particularly well preserved, they are divided into nine endogamous subcastes, which in tum are subdivided into exogamous clans or septs. Many of the latter are totemic, for example, the Patrischi or Bean Clan, members of which will not touch beans" (Andrews 1949: 277n). Once again, it is my experience that fava beans are still widely consumed in western India today. AFRICA Andrews has one short but noteworthy comment on Mrica: "Among the Baganda in the vicinity of Lake Victoria Nyanza, the Bean Clan will not eat or even cultivate beans. One of them is said to have eaten beans and died on the spot" (ibid.).

Other Biological Effects of Fava Beans Fava beans have a considerable concentration of indigestible oligosaccharides, which are digested by bacteria of the lower gastrointestinal tract, the likely cause of the flatulence reported in the cultural data presented above. However, they also contain a high concentration of L- D 0 PA (approximately 0.25 percent by weight). L- DO PAis a potent psychoactive neurotransmitter that is known to be associated with the other symptoms Plutarch described and is consistent with English folklore. Moreover, the dose of L- DO PA obtained from one or two meals of fava beans appears to be in the range that can be effective in treating Parkinson's disease, which is the principal source of clinical data on the effects of L- DO P A Oamalian 1978; ]amalian, Aylward, and Hudson 1977). Thus, it is conceivable that beside their agricultural efficiency and nutritional value, their possible psychoactive effects may be associated with their continued consumption. This combination of effects appears to fit well with the Greek word hieros, which Andrews (1949) suggested conveys the mixture of dread and respect that was applied to the hannful or beneficial supernatural force associated with the consumption of fava beans. Andrews sums up the magnitude and complexity of the "infonnation pool" that was accumulated in ancient and historic times by concluding that "no plant or animal known to the lndo-Europeans produced a more luxuriant growth of beliefs than fava beans" (1949: 290).

153

II. Bioevolutionary Antecedents and Constraints

Conclusion The evidence suggests that fava bean consumption throughout the circumMediterranean region fits a complex model of interacting biological and cultural evolution. The beans undoubtedly have highly toxic effects for many G6PDdeficient individuals, and hence there is extensive evidence for the development of taboos surrounding their use, particularly in children. In addition, many recipes for preparing the beans lower their toxic effects. However, consumption of the beans has continued since neolithic times, and it is clear that neither the taboos nor the processing techniques have mitigated this problem sufficiently to prevent a high incidence of favism. Even though their agricultural potential in the circum-Mediterranean region is high, it is still difficult to explain their continued use in light of the high morbidity and mortality rates in G6PDdeficient individuals. Hence, the evidence tends to support the addition of increased resistance to malaria as another major factor adding selective advantage to their continued consumption. Several classes of pharmacologically active compounds in fava beans that appear to be responsible for the favism crisis in G6PD-deficient individuals produce similar increases in the oxidant sensitivity of the RB Cs in normal individuals without toxic effects. Various epidemiological and biochemical evidence supports the hypothesis that an increase in RBC oxidant sensitivity as a result of fava bean consumption could lower rates of infection with malarial parasites and, therefore, be highly advantageous (Papavasiliou et al. 1972). If this hypothesis is fully substantiated, it would provide the first evidence that the biological and cultural evolution of disease resistance are linked through dietary practices. This paper has also attempted to demonstrate the complex interactions between changes in the gene pool and changes in cultural knowledge, which accumulates over time a set of adaptive practices and information about the effects of fava bean consumption. Topics that call for further exploration in light of these cultural data include quantitative aspects of the evolution of the Mediterranean type of G6PD deficiency; folk knowledge of the sex-specific effects of the beans on males but not females, and the folk behavior and beliefs about females as carriers of the potentially lethal condition; and further research concerning the efficiency of folk medical practices for treating favism and the relations of these practices to the anti-malarial potential of the beans. The mechanism of transfer of this folk knowledge from one generation to the next and the roles of rituals and ideologies in this process could provide important clues for the assembly of a more sophisticated model. Finally, fava beans are still very widely consumed, and there is a need to integrate these findings with knowledge of contemporary social, agricultural, and food practices. The apparent net effect of these interactions is a dynamic equilibrium between biological and

154

5. Fava Bean Consumption

sociocultural dimensions, which, I suggest, provides a test case for understanding the co-evolution of genes and culture as it relates to the human food chain.

Acknowledgments 'fhe ideas and data presented in this revised and updated paper are largely derived from Katz (1979). A more extensive discussion of the human biological aspects of the problem is given in Katz and Schall (1986), in which Figure 5.4 appeared. Figures 5.1b, 5.2, 5.3, and 5.6 appear courtesy of AVI Publishing, from Katz: Food, Behavior and Biocultural Evolution, in L. M. Barker, ed., The Psychobiology ofHuman Food Selection, pp. 171-88, © 1982 by the AVI Publishing Company, Westport, CT 06881. Figure 5.5 and 'fable 5.1 appear courtesy of Medical Anthropology (see Katz and Schall 1979), © 1979 Redgrave Publishing Co., Bedford Hills, N. Y.

Note 1. This wide range of enzyme variants has given rise to several notation systems for

C; 6 P D deficiency, such as Gd -, which refers to the deficient variant of the enzyme.

References Cited Andrews, A. C. 1949 The Bean and Indo-European Totemism. American Anthropologist 51:274-92. Arie, T. H. D. 1959 Pythagorus and Beans. Oxford Medical School Gazette 2: 75-81. Belsey, M. A. 1973 The Epidemiology of Favism. Bulletin of the World Health Organization 48: 1-13. Beutler, E. 1970 L-Dopa and Favism. Blood 36:523-25. Bienzle, U.; A. O. Lucas; O. Ayemi; and L. Luzzato G6PD and Malaria. Lancet 1: 107-10. 1972 Bottini, E. 1973 Favism: Current Problems and Investigations. Journal ofMedical Genetics 10: 213-19. Bottini, E., et a1. 1970 Presence in Vicia faba of Different Substances with Activity in vitro on Gd - Med Red Blood Cell Reduced Glutathione. Clinica Chemica Acta 30:831-34.

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II. Bioevolutionary Antecedents and Constraints

Bottini, E., et al. 1971 Favism: Association with Erythrocyte Acid Phosphotase Phenotype. Science 171: 409-11. Carcassi, L. E. F. 1974 The Interaction Between B-Thalassemia, G6 P D Deficiency and Favism. Annals of the New York Academy of Sciences 232: 297-305. Celsus 1935 De Medicina, W. G. Spencer, trans. Cambridge: Harvard University Press. Chevion, M., and T. Novak 1983 Favism. Annals ofBiochemistry 128: 152-53. Crosby, W. H. 1956 Favism in Sardinia. Blood 11:91-92. Eaton, ]. W., and]. R. Eckman 1977 Glutathione Metabolism in Malaria Infected Erythrocytes. Clinical Research 25:610. 1979 Plasmodial Glutathione Metabolism: Dependence Upon the Host Cell. Nature 278: 754-56. Eaton,]. W.;]. R. Eckman; E. Berger; and H. S. Jacob 1976 Suppression of Malaria Infection by Oxidant Sensitive Host Erythrocytes. Nature 264: 75~-60. Etkin, N. L., and]. W. Eaton 1975 Malaria Induced Erythrocyte Oxidant Sensitivity. In Erythrocyte Structure and Function, G. ]. Brewer, ed., pp. 219-32. New York: Liss. Friedman, ]. M. 1978 Increased Oxidant Sensitivity of Malaria Parasites Glucose-6-Phosphate Dehydrogenase Deficient and Thalassemia Trait Red Cells. Blood 52 (suppl. 1): 64. Giles, E. 1962 Favism, Sex Linkage, and the Indo-European Kinship System. Southwestern Journal ofAnthropology 18: 286-90. Golenser, ].; ]. Miller; D. T. Spiro; T. Novak; and M. Chevion 1983 Inhibitory Effect of a Fava Bean Component on the In Vitro Development of Plasmodium falciparum in Normal and Glucose-6-Phosphate Dehydrogenase Deficient Erythrocytes. Blood 61:507-10. Herodotus 1947 The Persian Wars. New York: Random House. Huheey, ]. E., and D. L. Martin 1975 Malaria, Favism, and G6PD Deficiency. Experientia 30: 1145-47. Iversen, L. I. 1975 Dopamine Receptors in the Brain. Science 188: 1084-89. Jamalian, ]. 1978 Favism-Inducing Toxins in Broad Beans (Vicia faba) Determination of Vicine Content and Investigation of Other Nonprotein Nitrogenous Compounds in Different Broad Bean Cultivars. Journal of the Science of Food and Agriculture 29: 136-40.

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5. Fava Bean Consumption

Jamalian, ].; F. Aylward; and B. ]. F. Hudson 1977a Favism-Inducing Toxins in Broad Beans (Vicia faba): Biological Activities of Broad Bean Extracts in Favism Sensitive Subjects. Plant Foods for Human Nutrition 27:213-19. 1977b Favism-Inducing Toxins in Broad Beans (Vicia faba): Estimation of the Vicine Contents of Broad Bean and Other Legume Samples. Plant Foods for Human Nutrition 27:207-11. Katz, S. H. Evolutionary Perspectives on Purpose and Man. Symposium on Human 1973 Purpose. Zygon 8:325fl-40. Un Exemple d'Evolution Bioculturelle: La Feve. Communication 31:531979 69. Favism, G6PD Deficiency and Malaria: The Evolution of G6PD Defi1981 ciency. Unpublished Manuscript. Food, Behavior and Biocultural Evolution. In The Psychobiology of 1982 Human Food Selection, L. M. Barker, ed., pp. 171-88. Westport, Conn.: AVI. Katz, S. H.; L. Adair; and J. Schall 1975 Fava Bean Consumption, Malaria and G6PD Deficiency. American Journal ofPhysical Anthropology 44: 189. Katz, S. H., and E. F. Foulks 1970 Calcium Homeostasis and Behavioral Disorders. In Symposium on Human Adaptation, S. H. Katz, ed. Journal of Physical Anthropology 32: 225-316. Katz, S. H.; M. L. Hediger; J. Schall; and L. Valleroy 1983 Growth and Blood Pressure. In Clinical Approaches to High Blood Pressure in the Young, T. and M. Kothchen, eds., pp. 91-132. Boston: John Wright/ PSG Inc. Katz, S. H.; M. L. Hediger; and L. Valleroy 1974 Traditional Maize Processing Techniques in the New World: Anthropological and Nutritional Significance. Science 184: 765-73. 1975 The Anthropological and Nutritional Significance of Traditional Maize Processing Techniques in the New World. In Symposium on Biosocial Interrelations in Population Adaptation, Wayne State University, 1973. In Biosocial Interrelations in Population Adaptation, E. S. Watts, F. E. Johnson, and G. W. Lasker, eds., pp. 195-234. The Hague: Mouton. Katz, S. H., and J. Schall 1977 Fava Bean Consumption, Malaria and G6PD Deficiency. American Journal ofPhysical Anthropology 46: 178. Fava Bean Consumption and Biocultural Evolution. Medical Anthropol1979 ogy 3: 459- 76. 1986 Favism and Malaria: A Model of Nutrition and Biocultural Evolution. In N. Etkin, ed., Plants Used in Indigenous Medicine and Diet: Biobehavioral Approaches. New York: Redgrave Press. Katz, S. H.; J. Schall; P. Sundick; and J. Coleman 1978 Fava, Biocultural Evolution and Favism. American Anthropological Association Abstracts, no. 78.

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Katz, S. H., et a1. 1985 Adrenal Androgens, Body Fat and Advanced Skeletal Age in Puberty: New Evidence for the Relations of Adrenarche and Gonadarche in Males. Human Biology 57:401-403. Kirkman, H. N. 1968 G6PD Variants and Drug Induced Hemolysis. Annals of the New York Academy ofSciences 151: 753-64. Kosower, N. S., and E. M. Kosower 1967 Does 3,4-dihydroxyphenyalanine Play a Part in Favism? Nature 215:285-86. 1970 Molecular Basis for Selective Advantage of G 6 P D Deficient Individuals Exposed to Malaria. Lancet 2: 1343-45. 1974 Effect of Oxidized Glutathione on Protein Synthesis. In Genetic Polymorphisms and Diseases in Man, B. Ramot, ed., pp. 349-57. New York: Academic Press. Liebowitz, ]., and G. Cohen 1968 Increased Hydrogen Peroxide Levels in Glucose Erythrocytes Exposed to Acetylphenylhydrazine. Biochemical Pharmacology 17:983. Lin,]. Y. 1963 Studies on Favism, 4: Reactions of Vicine and Divicine with Sulfhydrl Group of Glutathione and Cytesine. Journal of the Formosan Medical Association 62: 777-8l. Lin, ]. Y., and K. H. Ling 1962a Studies on Favism, 1: Isolation of an Active Principle from Fava Beans (Vicia faba). Journal of the Formosan Medical Association 61:484-89. 1962b Studies on Favism, 2: Studies on the Physiological Activities of Vicine in vivo. Journal of the Formosan Medical Association 61:490-94. 1962c Studies on Favism, 3: Studies on the Physiological Activities of Vicine in vitro. Journal of the Formosan Medical Association 61: 579-83. Livingston, F. B. 1964 Aspects of the Population Dynamics of the Abnormal Hemoglobin and G6PD Deficient Genes. American Journal ofHuman Genetics 16:43550. 1967 Abnormal Hemoglobins in Human Populations. Chicago: AIdine. 1973 Data on the Abnormal Hemoglobins and G6PD Deficiency in Human Populations. University of Michigan Technical Reports, no. 3, pp. 1216. Ann Arbor: University of Michigan. Luzzatto, L.; E. Usanga; and S. Reddy 1969 Glucose 6 Phosphate Dehydrogenase Deficient Red Cells: Resistance to Infection by Malarial Parasites. Science 164:839-42. Mager, ].; M. Chevion; and G. Glaser 1980 Favism. In Toxic Constituents ofPlant Foodstuffs, I. E. Liener, ed., pp. 265-94. 2nd ed. New York: Academic Press. Mager, ].; A. Razin; and A. Hershko 1969 Favism. In Toxic Constituents ofPlant Foodstuffs, I. E. Liener, ed., pp. 293-318. New York: Academic Press.

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Motulsky, A. G. 1965 Theoretical and Clinical Problems of Glucose-6-Phosphate Dehydrogenase Deficiency. In Abnormal H aemoglobins in Africa: A Symposium Organized by the Council for International Organizations of Medical Sciences Established Under the Joint Auspices of UNESCO & WHO, ]. H. P. Jonxis, ed., pp. 143-96. Philadelphia: Davis. Mourant, A. E.; A. C. Kopec; and K. Domaniewska-Sobczack 1976 The Distribution of Human Blood Groups and Other Polymorphisms. London: Oxford University Press. Papavasiliou, P. S.; G. C. Cotzias; S. E. Dueby; A.]. Steck; C. Fehling; and M. A. Bell 1972 Levodopa in Parkinsonism: Potentiation of Central Effects with a Peripheral Inhibitor. New EnglandJournal ofMedicine 285:8-14. Rowlett, R. M., and j. Mori 1970 The Fava Bean in English Folklore. Ethnologia Europea 4:98-102. Sartori, E. 1971 On the Pathogenesis of Favism. Journal of Medical Genetics 8:462-67. Siniscalco, M.; L. Bernini; G. Fillipi; B. Latte; P. Meera Khan; S. Piomelli; and M. Rattazzi 1966 Population Genetics of Hemoglobin Variants, Thalassemia and G6PD Deficiency with Particular Reference to the Malaria Hypothesis. B ulletin of the World Health Organization 34: 379-93. Siniscalco, M.; L. Bernini; B. Latte; and A. G. Motulsky 1961 Favism and Thalassemia in Sardinia and Their Relationship to Malaria. Nature 190: 1179-80. Spielberg, S. P.; L. A. Boxer; L. M. Corash, j. D. Schulman 1979 Improved Erythrocyte Survival with High Dose Vitamin E Therapy in Chronic Hemolyzing G 6 P D and Glutathione Synthetase Deficiencies. Annals of Internal Medicine 90:53-54.

159

Nutritional and Biopsychological Constraints THE ESSAYS OF PART III DEAL WITH GENETICALLY DETERmined biopsychological factors that affect foodways from the standpoint of nutritional adequacy and"taste." From a materialist perspective, it is axiomatic that human foodways that lead to severe malnutrition will tend to be selected against during both biological and cultural evolution. But this leaves us with the question of how much of what kinds of nutrients in what proportions and at what stage of life for males and females (including pregnancy and lactation) with different somatotypes and under varying conditions of health will result in a severely malnourished population. As the essays by Pellet and Lieberman make clear, nutrition is far from being an exact science. Not only are recommended daily allowances extrapolated from experiments on non-human models and from causally ambiguous epidemiological data, but to a considerable extent they express the outcome of political infighting between representatives of developed and developing nations as well as that between the vested interests of the agri-businesses and medical-nutritional establishments. Attempts to relate foodways to minimum nutritional requirements are further complicated by the existence of some innate taste preferences and avoidances. It is possible that these biopsychological features account for the overconsumption of certain foods (e.g., sugar) or the selection of certain less nutritious foods when more nutritious ones are available (e.g., candy versus grains). Yet, as Rozin's essay shows, cultural conditions can readily turn innately aversive substances l£ke hot chili peppers into the dominant taste signature of whole cuisines. The interplay between cultural conditioning and nutritional requirements is especially baffling in relation to the widespread preference for animal food, whose existence is documented in Abram's essay. As Lieberman's essay shows, from a strictly nutritional point of view, neither animal nor plant foods can be said to be more suitable as a source of essential nutrients, nor can either be said to be free of

161

III. Nutritional and Biopsychological Constraints

nutritional risks and penalties when overconsumed. But it should be kept in mind that the evolution offoodways is probably subject to selection by costs and benefits that encompass more than the strictly nutritional composition offoods. Thus, the preferences for animal foods, especially for meat, may be a response to the higher density" of calories and nutrients packed into a gram of meat versus a gram of plant food. We will return to this issue in Part IV. H

162

P. L.PELLETT

Problems and Pitfalls in the Assessment of Human Nutritional Status MORE THAN 40 SEPARATE ELEMENTS OR COMPOUNDS HAVE NOW been identified as necessary for life, together with at least 40 grams per day of amino acids as protein and more than 200 grams per day of a mixture of carbohydrate, protein, and fat that can be metabolized for energy. Although all these materials are required for daily metabolism to proceed, it is not necessary that they all be provided daily in the diet. The ability of the body to draw on reserves or stores allows varying amounts of time to elapse before deficiencies may be recognized. Oxygen (if that be a nutrient) is needed continuously, water deprivation cannot last for more than a few days; total food deprivation can last for weeks to months, depending on fat reserves; whereas vitamin A stores may last for more than a year on essentially zero intake (Hume and Krebs 1949). Daily requirements for nutrients also vary enormously, ranging from microgram quantities for Vitamin B12 , milligram quantities for many minerals and most vitamins, gram quantities for individual essential amino acids, calcium and phosphorus, and, of course, several-hundred-gram quantities of energyproviding materials. The distinction between required and non-required nutrients is not always clear-cut. Fiber is necessary in the diet for optimal health, yet it is not a nutrient; its function, indeed, is not to be absorbed. Several mineral elementsfor example, zinc, copper, and selenium-have only relatively recently been demonstrated as essential nutrients, but nickel, tin, and vanadium remain in the uncertain category. Of the essential amino acids, histidine is now known to be required by adults, but the demonstration of deficiencies can take months, since the amino acid can be synthesized in the body, but only at a rate somewhat below requirements. Normal individuals can manufacture as much cystine and tyrosine, as they need; thus, these two amino acids are termed non-essential (non-essential amino acids are so essential that the body has learned to synthesize them!). Under conditions of liver damage, however, cystine and

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III. Nutritional and Biopsychological Constraints

tyrosine can no longer be synthesized fast enough from methionine and phenylalanine respectively, so that they become essential and must be supplied in the diet (Horowitz et al. 1981). With some vitamins, synthesis may occur (invalidating some of our definitions): the well-known example of nicotinic acid, synthesized from the amino acid tryptophan, complicated the search for the cause of pellagra (Horwitt et al. 1955). Vitamin D (cholecalciferol) can be synthesized in the skin, and it functions more as a hormone than as a vitamin (DeLuca 1974). Even vitamin C, the first discovered if not first named of the vitamins, whose lack has probably influenced human history more than any other deficiency, may be synthesized to a very limited degree in pregnancy and lactation (Rajalakshmi et al. 1965). Diets (and most individual foods) are mixtures of nutrients, in varying proportions, along with other compounds such as fiber (of various types), phytates, cholesterol, natural toxicants, and trans-fatty acids, which may be harmful or beneficial. No single food can supply all our needs for long, and the lack of intake of a single food mayor may not affect the intake of nutrients. A safe rule of thumb is that the more components there are in a dietary, the greater the probability of balanced intake. The corollary of this is that monotonous dietaries with few components are more likely not only to show deficiencies, but to be seriously affected by dietary avoidances. The assignment of credit or blame to dietary intake for the development or prevention of malnutrition is much less straightforward than many assume, both inside and outside the field of nutrition. Nutritional status and health status overlap; adaptation to high or low intakes may occur; nutritional requirements, although based on scientific facts, depend on informed judgments and are subject to a wide range of individual variability; and, finally, estimates of nutrient intakes are only approximate except under controlled metabolic conditions that are hardly nonnal. It is thus not surprising that the role of food preferences and food aversions in nutrition must often remain anecdotal and equivocal. It is now increasingly recognized that malnutrition may be caused less by nutrient deficiency as such and more by many interrelated social, political, and economic factors Oohnsson 1981; Pellett 1983); the widespread prevalence of malnutrition is usually a symptom of a very sick society (Maletnlema 1980). Because of this multifactorial causation, solutions must also be multifaceted, even if such measures as the elimination of poverty and improvement of living standards are basic. Malnutrition affects the growth, development, and survival of children and the health, activity, and well-being of adults. Conventional solutions in the form of specific programs are usually inadequate, and their effects are transitory, since they do not reach causes. Nutrition can be improved through upgrading living standards-particularly the level of real income, food availability, and health services. Solutions will be found, therefore,

164

6. Problems and Pitfalls in the Assessment of Human Nutritional Status

mostly outside the traditional nutritional field, in economic and social development. Although the tenn "malnutrition" strictly should include overnutrition and some of the diseases of affluence, it is often used only to refer to the condition resulting from a deficient intake of energy or of a particular nutrient. Four especially important and broad causes of malnutrition are the following: 1. Insufficient supply of the foods necessary for a balanced diet, often due to production failure, poor soil, climate, and fanning techniques, or overpopulation 2. Uneven distribution of the available food (both between and within families) 3. Lack of knowledge about nutrition and health 4. Poor health and sanitation, including infectious diseases that are synergistic to malnutrition (Latham 1979) It must, of course, be recognized that these causes are not separate and distinct causes, but overlap with each other. The characteristics of the major world nutritional disorders are summarized in Table 6.1. The fundamental roles of health, wealth, and sanitation factors must be recognized. Nevertheless, depending on the disorder, actions can be taken to improve the nutritional status of the most vulnerable groups, which are women of child-bearing age and young children. The causes of malnutrition for individuals or communities can be grouped into the levels summarized in Figure 6.1. These levels are related to moneybased societies, but similar levels, overlapping in various ways, exist in other societies. Under present-day economic conditions, causes of malnutrition start with overall food availability. This is affected by international and national political-economic activities as well as agricultural policy both within and external to the country. The next determinant is family purchasing power. This also is dependent on political and economic factors, but at a more local level. Thus, what food is purchased is determined both by food availability and by economic status and money availability. At the next level comes food choice. Within any economic group, the pattern of food purchases is dependent on likes and dislikes as well as the relative prices of the various foods. Nutrition education can work at this level by encouraging selection of nutrient-rich foods over nutrientpoor sources with the same cost. However, nutritional education has been far less effective than we would wish (Schiirch 1983). The next level below the family food-purchasing pattern, and overlapping it to some degree, is the pattern of food distribution within the family. This is dependent on culture and is frequently a major cause of malnutrition in the vulnerable groups. Women's and children's greater need for protein and micro-

165

TABLE 6.1. The Characteristics of Hunger and the Major Nutritional Disorders Protein-Energy Malnutrition (PEMb) Nutritional Marasmus

Hunger a

Characteristics

Kwashiorkor

Causation/ precipitation Long-term

Poverty, poor

Low-protein diet

agriculture

Immediate

Vulnerable groups

Poverty, crop

Early weaning,

failure, war

infections

All ages

Children under 1

Children between 1

year

and 2 years

and main age of

Infections

incidence Major features

Growth failure,

Wasting

Edema, fatty liver, reduced serum

wasting, lethargy

albumin

Consequences

Reduced growth,

High mortality,

High mortality,

reduced work

impaired mental

impaired mental

capacity, high

development

development

mortality Areas of incidence

All areas of poverty

Urban areas, large

Rural Africa, areas

families with low

with low-protein

incomes and poor

weaning foods

education Prevalence

High

Widespread in poor areas

Increasingly rare in Middle East and North Africa

166

Xerophthalmia

Low intakes of

Goiter

Low intakes of iodine

carotene and/or

Iron-deficiency Anemia

Low intake/ absorption of iron

retinol

Low Birth-Weight (LBW) Infants c

Poor dietary intake since conception, infections of mother

Early weaning,

Blood loss from

Low weight gain in

infections

infestations

pregnancy

Older children,

Children « 3 years)

Mothers of poor

females

and females of child-

socioeconomic status

Preschool children

bearing age Night blindness,

Enlarged thyroid

xerosis of

Low hemoglobin

Hypoglycemia,

(microcytic

hypothermia, poor

conjunctiva and

hypochromic anemia

resistance to

cornea,

if severe)

infection (low IgG)

Pallor, reduced work

High mortality,

keratomalacia, low serum retinol High mortality

Cretinism

especially when

and learning

suboptimal

associated with

efficiency

development, high

PEM, blindness

incidence of infection

Rice staple areas,

Areas with low soil

areas of poverty

iodine, mountain

Ubiquitous

Low socioeconomic areas with high

areas and certain

prevalence of

oases

infections

Not widespread in

High in localized

wheat-staple areas of

areas

High

Incidence highly correlated with

Middle East and

socioeconomic

North Africa

indicators-possibly 20 percent of all births in poor areas (continued)

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III. Nutritional and Biopsychological Constraints

TABLE 6.1. (cont.) Protein-Energy Malnutrition (PEMb) C haracteristics Measures to eliminate

Hunger a

Nutritional Marasmus

Kwashiorkor

Major

Major socioeconomic

Control of infections,

socioeconomic,

and educational

higher protein in

agricultural, and

improvements,

weaning foods

educational

control of infections

improvements

SOURCE: Pellett (1983). aThere is a considerable degree of overlap of causation, consequences, and prevalence of proteinenergy malnutrition with low birth weight infants. b PEM when early or of mild to moderate severity is usually sub-clinical and can only be diagnosed by anthropometric criteria (weight/age, height/age, and weight/height). c Infants of birth weight below 2,500 grams. In developing countries the majority of cases are due to fetal growth retardation.

nutrients, despite their lower food-energy needs-that is, their need for a higher concentration of nutrients-is often difficult to impart, since nutritional education will frequently conflict with cultural nonns. Finally, because of the now well-known inter-relationship between malnutrition and infection (Chen, 1983; Scrimshaw, Taylor, and Gordon 1968), consumed food may not be fully utilized. An individual suffering from infection (or infestation) may not only have a reduced food intake, but may also have poorer utilization for a range of nutrients. Sanitation and the availability of clean water thus profoundly affect nutritional status. Techniques for evaluating the nutritional status of populations can also come from a consideration of various levels of infonnation. These can be separated into two major categories, the first pertaining to agriculture and food availability, the second pertaining to the health of the population. These are shown in Table 6.2. Agriculture and food production data have limitations, but they can indicate the approximate availability of food supplies and nutrients to a population. Close examination of agricultural production data can also allow judgments on the success or failure of agricultural techniques. The next level of infonnation concerning food derives from dietary surveys and food consumption patterns within the society and provides data about socioeconomic variables and

168

6. Problems and Pitfalls in the Assessment of Human Nutritional Status

Xerophthalmia Increased

Iron-deficiency Anemia

Goiter Iodine enrichment

Iron enrichment,

Low B irth-Weight (LBW) Infants e Maternal nutrition

consumption of

control of

programs,

green vegetables,

infestations

prevention of infections, major

fortification, improved

socioeconomic and

socioeconomic

educational

conditions

improvements

FIGURE 6.1. Major Factors Affecting Nutritional Status Causes/Solutions

Sequence

International and national politics and economics, agri-

Food availability

1

cultural policy, production and distribution Political and economic factors at a local level

Family IurChaSing power

Targeted economic assistance ~

Family food-purchasing pattern

1

Improved purchasing power

Poor nutrition knowledge

~

Witrun-rmilY food distribution

Nutrition education ~

Improved food selection

Poor nutrition knowledge Nutrition education, targeted food assistance ~

Utilization of foods by consumer

1

Improved food distribution

Infection, infestation, poor sanitation Health advice and services ~ Improved food utilization

Individual nutritional status SOURCE: Sequence adapted from Pinstrup-Anderson (1982).

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III. Nutritional and Biopsychological Constraints

TABLE 6.2. Infonnation Needed for the Assessment of Nutritional Status Food-Related Data Category Method

Country

Individual

Food balance

Dietary surveys

sheets

Health-Related Data Country

Individual

Vital and health

Anthropometric,

statistics

biochemical, clinical testing

Information

Approximate

Approximate

Morbidity and

availability of

nutrient intakes

mortality data

nutrition on

food supplies per

of individuals and

and degree of

physical

capita

Effect of

comparison with

risk to the

development,

nutritional

community

biochemical

requirements

function, and development of clinical abnormalities

the distribution and storage of foods. Dietary surveys, though difficult to perform with accuracy, can give the most detailed information on food and nutrient consumption at the family level. Conversion of food intake to nutrient intake is now performed rapidly through the use of computers, but is still dependent on both judgment and the accuracy of food-table data. Once nutrient intake data are established, these must be compared with standards before decisions can be made concerning the nutritional value of the diet. Derivation of the appropriate requirement standards and comparison with intake values does not always allow clear-cut conclusions concerning either the nutrient or the diet as a whole. A recent definition of nutritional requirements comes from the Canadian recommended nutrient intakes (Bureau of Nutritional Sciences 1983). "Requirement" is taken to mean that level of dietary intake of a nutrient that meets an individual's need, defined as the establishment and maintenance of a reasonable level in tissues or stores in the body. In the case of energy, the requirement is considered to be the level of intake needed to maintain appropriate body size and composition and expected work and leisure activity. For infants, children, and pregnant women, the requirement is meant to include needs for the deposition of new tissues, and for lactating women, the production of milk. A similar definition is used for the recommended dietary allowances (RDAs) in the

170

6. Problems and Pitfalls in the Assessment of Human Nutritional Status

United States, which appear at four- to five-year intervals. The most recent of these appeared in 1980 (NAS-NRC 1980) although a 1985 version has been prepared and is awaiting publication. All of these definitions refer to the nutrients needed to maintain health in already healthy individuals. Among normal individuals, requirements for many nutrients are affected by the nature of the diet, body size, activity, age, sex, and physiological state. There is thus individual variability, and the requirements for a group will show a range, although in tabular presentations an average for a set of reference individuals is often shown. RDA is supposed to take into account individual variability and to meet the requirements of almost all individuals in a group of specified characteristics. For food energy, in contrast, average requirements are specified because both inadequate and excess intakes of energy sources may present a risk to health. Because of this major difference, food energy was removed from the main summary table of the 1980 edition of the RDAs, and average food energy allowances are now tabulated in the energy section, where they are shown together with a range for adults of ±400 kilocalories per day. Thus, the approach to drawing conclusions from the average intakes of groups of individuals will differ for energy and for other nutrients. Human protein and energy needs are addressed in depth about every decade by an international group under the auspices of the Food and Agricultural Organization (FAO) and the World Health Organization (WHO). The United Nations University (UNU) collaborated in the most recent report (FAO /WHO/UNU 1985). Although the actual recommended allowances for protein and energy do not differ greatly from previous recommendations, the basis used for both recommendations has changed. The new report notes the apparent paradox of the survival of populations that consume only 80 percent of their estimated energy needs. These populations adapt to these lower energy intakes by a reduction in activity. This has been documented by Viteri (1976) for Guatemalan plantation workers, whose productive capacity is limited by their food intake but who remain almost inactive when their day's work is completed. Mter additional food was provided, both consumption and activity increased. The new report emphasizes the importance of adequate food for discretionary as well as work activities and underlines the obvious (but often ignored) fact that it is impossible to establish an appropriate average figure for a population's energy requirements unless their activity level is also specified. Not only do individuals adapt, but whole societies may develop patterns compatible with low food intakes, which may not, however, be compatible with their long-term interests. The report suggests a simplified approach to estimating energy needs in which needs are defined as follows: food energy need == basal needs x activity,

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III. Nutritional and Biopsychological Constraints

where basal needs are calculated from a fonnula that includes sex, age, and weight and an appropriate activity factor is either calculated from daily activity patterns or assigned. These assigned factors would range from 1.4 for light activity to 2.2 for heavy activity. It has been recognized for some years that the daily allowance of 0.57 grams per kilogram of high-quality protein (egg, fish, milk) recommended by the FAO/WHO (1973) committee was too low (Garza, Scrimshaw, and Young 1977). The FAO/WHO/UNU (1985) committee reviewed a number of short (in tenns of weeks) and long (in tenns of months) protein requirement experiments in humans and concluded that the new safe protein allowance should be o. 75 grams per kilogram, again expressed in tenns of eggs, fish, or milk. This is an apparent increase of 30 percent. In practice, recommended allowances will increase far less, because there had previously been an excessively large correction factor for protein quality, net protein utilization (NPU), a measure that takes into account digestibility and amino acid composition (see Chapter 9). If the N P U for mixed ordinary diets is assumed to be 70 percent, then the allowance of 0.5 grams per kilogram for high quality protein is increased to 0.8 grams for mixed dietary protein. Newer values for adult human amino acid requirements would now increase the N P U of the same mixed dietary protein to 90 percent, and thus the new allowance becomes 0.83 grams per kilogram, almost identical to the previous value. An interesting outcome for a rather divisive dispute-protein requirements have been increased, yet remain the same. The overall discussions have not significantly changed the now widely accepted view that many population groups can obtain adequate protein if they are able to obtain sufficient food; thus, agricultural policy should remain centered on total yields, and increases in protein concentrations in plant-breeding programs are not required (Nygaad and Pellett 1986). Despite this it remains true that there are many population sub-groups, especially among the poor, where protein intake may indeed be limited and increased protein is desirable. Direct comparison of dietary intakes with other standards, such as the RDAs, may still, however, lead to inaccurate conclusions. The problems categorized by the 1980-85 Committee on Dietary Allowances (N AS-NRC 1986), reached the following conclusions. (1) RDAs are for reference individuals and must be adjusted for individuals with other physical characteristics. (2) The RDAs are guidelines for separate essential nutrients, whereas people eat food, and rarely for the express purpose of consuming nutrients. No set of nutrient guidelines can adequately address these nonnutrient factors. (3) The guidelines are often incorrectly interpreted. RDAs cannot be used to determine the adequacy of the average consumption of a group. If a group's average consumption meets the RDAs, it cannot be concluded that all members of the group are well nourished, because the distribution within the group may be

172

6. Problems and Pitfalls in the Assessment of Human Nutritional Status

skewed; that is, some may be consuming more and some less. However, if the average intake is much below the RDAs, then it can be concluded that there may be a significant risk of malnutrition. Failure to meet the RDA in anyone day should not be interpreted as indicating poor nutrition, since the RDAs are set for intakes over time. Individual intakes below the RDA also cannot be interpreted as indicating poor nutritional status, since RDAs are set above the needs of many individuals. It is often assumed that the RDAs (except for energy) are set to meet the needs of 97.5 percent of the population. This is strictly true only for protein, where the coefficient of variation from a large number of requirement studies is known. For other nutrients the "safety factor" used is not consistent and differs in derivation and magnitude from nutrient to nutrient. A policy analogous to "caveat emptor' probably applies to all users of all RDAs. In addition to simple extraction of allowances from the summary table, careful reading of the text is required. The question whether the dietary survey method followed is appropriate may also arise. Vitamin AI carotene, for example, is present in high levels in relatively few foods and may thus be consumed only infrequently. For such nutrients, ordinary dietary recall methods, even when three-day recalls are used, may be misleading. Some vitamins are stored in the liver, so that nutritional status can be maintained if high levels of intake occur perhaps once or twice per month. The metallic micro-nutrient copper may also be in this category. For circumstances such as these, food frequency determination may permit more accurate predictions of nutritional status than dietary surveys. Vitamin A status can also be used as an example of how overall dietary circumstances may affect the relative importance of dietary preferences. Many children throughout the world have an aversion to green leafy vegetables. This aversion to the only cheap source of vitamin A activity (in the form of several carotenes of varying potency) may be life-threatening to children in Asian riceeating communities and can also lead to high levels of xerophthalmia and blindness. For a child in the United States or Europe whose vitamin A is readily obtained from animal foods, the same aversion is of little consequence. The paradox of blindness and vitamin A deficiency in individuals surrounded by lush, green vegetation rich in pro-vitamin A activity has been noted by McLaren (1963). Observations on the health of populations are also used to indicate nutritional status, although impairment of health can usually be directly ascribed to faulty nutrition only when corresponding food and nutrient intake data are available to correlate with the health data. These data start at the regional or country level, including vital and health statistics when they are available. These can identify the extent of risk to the community. At a more individual level, nutritional assessment includes anthropometric, biochemical, and clinical studies. Consid-

173

III. Nutritional and Biopsychological Constraints

eration of the results of such surveys can give information on the effects of nutrition on physical development, on the impairment of biochemical function, and on the deviation from health due to malnutrition. Assessment of nutritional status by newer functional tests (Solomons and Allen 1983) is an important innovation that may allow more specific conclusions to be drawn concerning nutrient deficiency and health. Poor apparent nutritional status-for example, as measured by inadequate growth and development of children-may be related more to infective disease or inadequate water supply and sanitation than directly to food availability and food selection. Analysis is further complicated by the synergistic relationship among these factors. Even the type of measurement used for anthropometry will often allow varying conclusions to be drawn (Table 6.3). Weight-for-age measurements in children may overestimate the prevalence of malnutrition when compared with weight-for-height measurements. Children from poor environments may weigh less than well-nourished children of the same age but, having adapted to the situation, may be apparently healthy. Are these children suffering from malnutrition or not? The answer depends on the definition used. Smaller overall size but balanced weight for height may be a reflection of adaptation to a lower level of total food energy intake. Adaptation can also occur for other nutrients. Two populations with large differences in protein intake may both be in nitrogen balance and meeting their requirements. Similarly, the population of New Zealand attains selenium balance at an intake much below that of the United States with no apparent effects on health (Levander 1982). For iron, the situation is even more complex. The RDA for iron is given as 10 milligrams per day for an adult male and 18 milligrams for an adult female. This, however, tells very little about how much iron is required in diets, because both the source of iron and the presence of phytates, oxalates, tannins, and crude fiber will greatly influence the biological availability of dietary iron. In general, iron of vegetable origin is poorly available, ranging from as low as 1 to 5 percent for leaf sources such as spinach, lettuce, and cassava leaves. In contrast, the heme iron in red meat is at least 10 to 20 percent absorbed and also improves the absorption of vegetable iron in the diet (Monson et al. 1978). Iron absorption is enhanced by ascorbic acid in the diet and reduced by protein deficiency. The adequacy of dietary iron intake is complicated still further by environmental factors. Hookworm, schistosomiasis, and malaria can increase iron loss from the body, and enteric infections may further decrease iron absorption. Clearly one can tell little about the adequacy of dietary iron intakes per se or the probability that they will be associated with the known consequences of iron deficiency, which can include reduced physical capacity and work performance and impaired resistance to infection, resulting in increased sickness.

174

6. Problems and Pitfalls in the Assessment of Human Nutritional Status

TABLE 6.3. National Nutrition Survey of Egypt: Anthropometric Criteria Used, in Percent Diagnosis

Weight for Height

Height for Age

Weight for Age

Moderately malnourished

95 2