Medical anthropology: Some contrasts with medical sociology

Medical anthropology: Some contrasts with medical sociology

MEDICAL ANTHROPOLOGY: SOME CONTRASTS WITH MEDICAL SOCIOLOGY* GEORGE M. FOSTER Professor of Anthropology. UC Berkeley. CA. U.S.A. Abstract-In spite ...

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MEDICAL

ANTHROPOLOGY: SOME CONTRASTS WITH MEDICAL SOCIOLOGY* GEORGE M. FOSTER Professor of Anthropology.

UC Berkeley. CA. U.S.A.

Abstract-In spite of many similarities. the fields of medical anthropology and medical sociology differ significantly in origins. in research methodologies, and in emphases. Medical anthropology has developed from three sources; (1) the traditional ethnographic interest in primitive medicine, (2) the culture and personality movement of the 1940s and (3) the international public health movement following World War II. A holistic. systems approach to research appears to characterize medical anthropology more than medical sociology. Anthropologists traditionally have studied the underdogs. the world’s primitive and peasant peoples. They reflect this orientation in their tendency to identify with patients and health workers near the bottom of the medical hierarchy. rather than with physicians and other high status professionals. In the final analysis the medical anthropologist sees problems in a cultural context. while the medical sociologist sees them in a social context.

IYTRODL CTION

the past three decades anthropology and sociology have witnessed a parallel development of interest in health and disease as major categories in culture and society, as well as a concern for the ways in which the special knowledge of these disciplines can contribute to the solution of health problems. Both liclda noi4 li>rmall! rccopnize subcategories -medical anthropology and medical sociology-as legitimate units denoting areas of research and teaching and increasing numbers of behavioral scientists describe themselves as “medical anthropologists” or “medical sociologists”. Medical anthropologists and medical sociologists find employment in schools of medicine. nursing and public health; in hospitals and health departments: and in traditional university departments as well. They do research on such topics as definitions of health and disease. social and cultural factors in the cause and incidence of disease, epidemiology. the training of medical personnel, medical bureaucracies, hospitals. communication problems between doctors and patients. innovation and change in medical beliefs and practices. mental health and drug addiction. In their professional formation. anthropologists and sociologists (including those whose chief interests lie in the health field) have been exposed to essentially the same formal and informal training and socialization processes. they share common bodies of theory and conceptualization and they know and often use each others research methodologies. At first glance the similarities between medical anthropology and medical sociology seem so patently obvious that one wonders whether, in fact. the division represents more than historical accident. the simultaneous spawning of new subdivisions by related but formall! distinct disciplines. Murray Wax. who among sociologists is especiall! close to anthropology During

and anthropologists.

appears

to believe that the dis-

* This paper V.XS originall\ prepared for the Mrdical 4r~rltrapolog!~,‘Yc~~slrtr~~ 6( I ). 1971 and this revised version appears with the permission of the Editor of the Newsletter. Christie W. Kiefer.

tinction is more apparent than real. Writing in bathropology and the Behavioral and Health Sciences, he says, In terms of a logical and systematic division of sociaiscientific labor, much of sociology and anthropology should be grouped together. For example. social psychology, ethnopsychology and psychological sociology are actually one’ field and the aftcmpt~ paratencss arc hnost comical [I]

to .IU~III!

thclr

d~s-

Undeniably the similarities between medical anthropology and medical sociology are pronounced and it is quite possible that the two fields will continue to be viewed as more similar than different. At the same time, there are significant differences between the two. in origin, in identification with the actors in health dramas, in research methodologies, in research topics and in baiic conceptual approaches to problems. It is to these differences, rather than the similarities, that I address myself.

ORIGINS

The roots of contemporary medical anthropology can be traced to three rather different sources; (1) the traditional ethnographic interest in primitive medicine. including witchcraft and magic, (2) the culture and personality movement of the late 1930s and 1940s with collaboration between psychiatrists and anthropologists and (3) the international public health movement after World War II. The subdivision of medical anthropology today called “ethnomedicine” is the lineal descendant of the early interest of anthropologists in the medical institutions of non-Western peoples. Since the beginnings of our discipline we have viewed medical beliefs and practices as a part of the total cultural repertoire of the peoples we study and we have routinely gathered data on them in the same way and for the same reason. that we have gathered data on all other aspects of culture: to have as complete an ethnographic record as possible. The diligence of early anthropolo$sts in this endeavor is illustrated by Clements who. m the first comparative worldwide survey of beliefs

-ilX

GEORGE .M. FOSTER

about disease causation. cites 219 sources. a high proportion _of them ethnographic [2]. Needless to say. in those days few if any anthropologists routinely collecting data on medical institutions were greatly concerned with the bearing of their findings on health problems of the people being studied; they would have been astonished had they been told that they were engaged in medical anthropological research. I see relatively little direct influence from early studies of non-Western medical beliefs and practices on the first stages of development of contemporary medical anthropology. Rather. it is the other way around. Anthropologists who today work in the health fields have “recaptured” and given a formal name to ethnomedicine and made it a part of their specialty. As medical anthropology has developed. especially in the broad areas of international public health and transcultural psychiatry, the practical as well as theoretical importance to these topics of knowledge about non-Western medical systems has become apparent. This recognition has sparked renewed interest in ethnomedical research. elevating it to major importance in medical anthropology. Except for these early studies of non-Western medicine. done largely as a part of tribal studies and except for the historical-comparative articles about primitive medicine by the physician-ethnologist Ackerknecht. most health related publications by anthropologists prior to 1950 deal with psychological and psychiatric phenomena [3]. Rare indeed are the items that deal with the social and cultural context of health behaviour per se. or of the cultural chasm separating practitioners of western medicine and their non-Western patients [4], Even much of this work is cast in a psychiatric or mental health context. It is interesting to speculate about what medical anthropology would be today if this early interest in psychoanalytic theory in cross cultural settings had remained the principal impetus in the field. Fortunately, a third vigorous impetus was to be given to medical anthropology. Although the Rockefeller Foundation had been engaged in international public health work since the early years of this century [S], it was only in 1942 that the United States government initiated cooperative health programs with the governments of a number of Latin American countries as a part of a broader technical assistance program. With the end of the war, with the establishment of the Point IV program and with the founding of the World Health Organization. major bilateral and multilateral public health programs in developing nations became a part of the world picture. Health workers in cross-cultural settings came to see far sooner than those working within their own cultures and particularly those involved in clinical medicine. that health and disease are as much social and cultural phenomena as they are biological. They quickly realized that the health needs of developing countries could not be met simply by transplanting the health services of industrialized countries. The corpus of data on primitive and peasant medical beliefs and practices which had been gathered by cultural anthropologists. in earlier years. their information on cultural values and social forms and their knowledge about the dynamics of social stability and change. provided the key that was needed to many

of the problems encountered in these early public health programs. Anthropologists vvere in a position to explain to health personnel how traditional beliefs and practices contlicted with Western medical assumptions. how social factors influenced health care decisions. and how health and disease are simply aspects of total culture patterns. which change only in the company of broader and more comprehensive socio cultural changes. Beginning in the early 1950s. anthropologists were able to demonstrate the practical utility of their knowledge (and of their research methods as vvell) to international public health personnel. many of whom welcomed anthropologists with open arms. Anthropology provided insight into why many programs were less successful than had been hoped and in some instances anthropologists were able to suggest ways to improve programs. The anthropological approach was acceptable to public health personnel. too. because it did not threaten them as professionals. They saw it as a .s& approach. in that it defined tl1c

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with the recipient peoples. During most of the 1950s both anthropologists and health personnel were content to believe that with adequate socimultural information on target groups. health programs could be designed and carried out in ways that would lead people to accept modern medicine. It was only later that we began to realize that we need equal information about the premises. values and practices of members of the health professions themselves and that we began to question seriously whether all of these premises and values are. in fact. valid. In any event. whatever shortcomings we now perceive in this early detinition of the problem. international public health was a hospitable field for anthropologists and the working relationships between early medical anthropologists and health personnel were perhaps the best in the history of applied anthropology. It is important to stress that throughout the 1950s most anthropologists working in health and medical fields assumed they were engaged in applied work. an area of interest described by Caudill as “Applied Anthropology in Medicine” [6]. The term “medical anthropology” did not come into common use until the early 1960s [7]. One of the advantages of the new label is that it permits us to see that there are both theoretical and applied sides to the field. which conform to Straus’ distinction between “sociology r$medicine” (the theoretical. the study of medical behavior) and “sociology in medicine” (the applied. the use of sociology in ameliorating health problems) [Cc]. Although the roots of medical anthropology are quite distinct. all three are cross-cultural and comparative. Most of the proto-psychiatric medical anthropology articles and books deal, not with American society. but with such groups as the Navaho. the Apache. the Salteaux. the Pilaga and the Indians of Guatemala. Today’s expression. “transcultural psychiatry”, has a legitimate ancestry. To this day concern with cross-cultural phenomena remains a major feature distinguishing medical anthropology from medical sociology. Not all medical anthropology, of course, is cross-cultural. nor does medical sociology

429

Some contrasts with medical sociology

ignore intercultural situations. Nevertheless, the major interests of the two groups can be divided on this point. In the pages that follow some of the other differences between medical anthropology and medical sociology, as I interpret the evidence, Cill be explored.

THE IDENTIFICATION

OF THE

RESEARCHER

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It is unfortunate. that social scientists have accepted the viewpoint of medical authority as norm and have used it as a reference point for their studies and action programs in TB hospitals” [IZ].

The social scientist studying tenant farming, education and family relations would not think of letting the landlord, the school administrator. or the parents set his research problems, says Roth. In like fashion;

Anthropologists traditionally have identified with and felt sympathy for, the peoples they study. Most 01‘thchc pc’oplcs have hccn underdogs. the powcrlcss; North Amercian Indians, Mexican peasants, African tribesmen in colonial settings. Not surprisingly, this identification is reflected in medical anthropology, L\.IlLYC I’C\GI rcI1 pr0hlcms.

stay in the hospital?” represents a bias in favor of the staff rather than the patient. Yet, says Roth;

Il~lVC

been determined, tend to be viewed from the side of the patient and perhaps of low status medical personnel, rather than from that of the physician and the other high status personnel. Today anthropologists increasingly are inclined to see the barriers to improving health care as rooted in medical personnel and bureaucratic systems rather than in the patient and his beliefs. When we observe a Mexican-American mother with little control of English in the office of an Anglo physician, we emphathize with her and we wonder why the physician often has so little understanding of the linguistic and cultural barriers that separate him from his patient. Anthropologists are. it may be said, “consumer advocates”. Medical sociologists, in contrast, tend to identify with. and view problems from, the point of view of the medical establishment. Rodney Coe puts it this way : Since medical sociology is an applied field, it is incumbent upon sociologists to demonstrate their value by solving problems which result in a product with a clear practical utility for their “client”-in this case. the medical profession [9].

he should not accept the values, the questions, the problems of physicians and hospital and public health officials as the proper reference points when making a study of medical treatment (yet this is what sociologists tend to do) [13]. The contrast between what I believe is a marked tendency (but by no means an absolute) for the sociologist

to identify with “management”, (i.e. medical personnel) and for the anthropologist to identify with the patient, is nicely illustrated by Glaser, who writes, Occasionally social scientists have observed the relationships between doctor and patient. the class differences between doctor and patient have been found to affect the success of their clinical relationship: since the less educated patient is less able to communicate with the doctor irk rhe latter’s own uocabdary, he is asked to give fewer reports and he receives fewer explanations and fewer instructions for home care than do patients of higher social classes c141.

I interpret this passage as placing the responsibility for a poor therapeutic interview on the patient who fails to communicate with the physician on the latter’s terms. In contrast and to illustrate, in Margaret Clark’s account of medical problems of MexicanAmericans in a California city, we are led to see how the patient’s cultural background makes it difficult for him fully to benefit from contemporary American medical care [15]. The reader’s attention is focused on the patient, and not on the physician.

And from Eliot Freidson we learn By and large. medical sociology has focused on the areas that the medical practitioner himself has considered problematic. adopting the conception of what is problematic from the profession itself without raising questions about the perspective from which the problem is defined. .In addition. .even when sociological studies have turned their attention to the health worker himself. they have adopted the perspective of the worker in that they have emphasized the health worker’s own conception of what is problematic about his own occupations with which he has worked [IO]. Freidson

sees this tendency

as in part “produced

by

relying on the survey questionnaire as the prime method of collecting data-an occupational disease of the sociologist that is present in all fields” [ll]. The sociologist Julius Roth has labeled this identification “management bias,” and in a study of a TB hospital. he shows how the sociologist unconsciously defines problems from the point of view of medical personnel. A common question asked by staff of social scientists is. “Why do patients leave the hospital against medical advice?” The fact that the question is asked in this form. rather than “Why do patients

METHODOLOGY

bulk of medical anthropology research has been based on a systems approach, a holistic view of health and disease in the context of cultural systems. As in other anthropological community research, participant observation emphasizing qualitative data has been the most productive research method. In contrast, a majority of medical sociologists utilize survey research as their main method, augmented by statistical and other quantitative information. Yet interestingly, when studying whole systems-specially hospitals-medical sociologists often more nearly approximate anthropologists in their The

I.CSC;II.CI~ methods than thq do OPT xxioloysts.

For

example, in Boys in White, Becker and his associates describe research that is purely ethnographical: We had no well-worked-out set of hypotheses to be tested, no data-gathering instruments purposely designed to secure information relevant to these hypotheses. no set of analytic procedures specified in advance [16].

430

GEORGE

M. FOSTER VOX-WESTERN

Further. We concentrated

on wliar students learned as well as on /low they learned it. Both of these assumptions committed us to working with an open theoretical scheme in which variables were to he discovered rather than with a scheme in which variables decided on in advance would be located and their consequences isolated and measured [17].

Participant observation was the principal research method and the emphasis was on “student culture”. Olesen and Whittaker, in their analysis of a school of nursing, frankly recognize their anthropological approach: “Some readers may assert that in the best anthropological tradition we ‘went native’, at least in a psychological sense” [18]. But. they say, “Our rationale was that the best way to understand a process was to become part of it” [19]. And Merton. in The Student Physician, notes the anthropological approach used in that study: Particularly in the early part of the present investigation and to some extent throughout its course, field observers have been conducting what is tantamount to a social anthropological study of the medical school and of associated sectors of the teaching hospital. The field workers have

observed the behavior of students, faculty, patients. and associated staff in the natural. that is to say, the social setting. They have made observations in lecture halls and laboratories; have, upon invitation, accompanied physicians and students on rounds to note the social interaction there; have spent time observing the kinds of relationships which develop between student and patient and between student and teacher. These many hours of observation have been recorded in several thousand pages of field notes. making up a detailed account of recurrent patterns of students’ experience [ZO].

Bloom, describing his research for Power and Dissent in the Medical School, writes ‘“The most salient question, it was decided, concerned the collective character of the institution and not its separate, more readily measurable assets” [21]. “To answer such questions,” he continues, the first step logically appeared to be in the tradition of ethnography-to observe. interview and participate-to become immersed in the environment and follow the flow of its currents of opinion and behavior [22].

The evidence, suggests that the problemrather more than narrow professional training-dictates the research methodology to be used. Just as anthropologists who work in urban areas make greater use of survey and statistical methods than do those who work in small communities, so do medical sociologists concerned with major social systems rely heavily on participant observation and related qualitative measures. Although, as pointed out in the first paragraph of this paper, medical anthropologists and medical sociologists are concerned with many of the same research topics. there are other areas that are totally or largely the domain of one or the other of the two disciplines. In medical anthropology, non-western medical systems, and biocultural phenomena such as evolutionary adaptation and nutrition. are among the specialties one notes.

>lEDICAL

SYSTEMS

Most medical sociologists are concerned only with American and European medical systems. Coe. who devotes an entire chapter in Sociol0g.r of’ .Clrciicir~c to “Systems of medical beliefs and practices” is the rare exception [23]. Freidson more nearly represents the sociological point of view. He acknowledges that a great deal of information on “popular” knowledge about and attitudes toward health has been gathered by anthropologists and sociologists. but believes that The greatest proportion of that literature IS grossly descrtptive [and that] by and large both anthropological studies using the idea of culture and sociological surveys of “popular knowledge” in industrial societies have been smgularly vague [24].

Most such studies, he continues. focus on particular illnesses, and are essentially catalogues “often without a classified index” [25]. In contrast, medical anthropologists are vitally concerned with non-Western medical systems. with what has come to be called “ethnomedicine”. They would take issue with Freidson. arguing that traditional Chinese medicine, Indian Ayurvedic medicine and Greek humoral pathology and its contemporary forms in Latin America are indeed true systems. whether they come with a classified index or not. Medical anthropologists believe UU medical systems are worth studying, for their intrinsic interest. for their contributions to the improvement of health levels and because of what they tell us about the wider views of the people concerned. We agree with Pellegrino who believes that: Medicine is an exquisitely sensitive mdicdtor of the dominant cultural characteristics of any era. for man’s behavior before the threats and realities of illness 1s necessarily rooted in the conception he has constructed of himself and his universe [26].

Like Pellegrino.

we believe that:

Every culture has developed a system of medicme which bears an indissoluble and reciprocal relationship to the prevailing world view. The medical behavior of individuals and groups is incomprehensible apart from general cultural history [27]. And.

we would

add,

cultural

BIOCULTURAL

patterns. PHENOMENA

Since anthropology is a biological as well as a social science, it is not surprising that medical anthropology has embraced biological phenomena. Particularly important in this context are such things as the problem of adaptation in cultural and biological evolution [28], the origin and spread of the sickle cell trait as influenced by cultural practices [29]. and the meaning of lactase deficiency in dietary evolution c301. NCTRlTlOlri

The interest of many medical anthropologists in the cultural and social aspects of nutrition and diet stand in striking contrast to the absence of interest in this topic among medical sociologists. Anthropologists. not surprisingly, took upon food and eating as one

Some contrasts with medical sociology

of the most important of all cultural categories, with biological, health. social and psychological implications. They are interested in relating beliefs and practices concerning food to the other major social and cultural institutions and they know that medical systems and health levelsincluding those in our own society--cannot fully be understood without reference to food. The symbolic significance of food, of food exchanges, of the offering of food as an expression of perceived social relationships-these, and many other matters dealing with nutrition and diet have interested, and will continue to interest. medical anthropologists. SUMMARY In summarizing the differences between medical anthropology and medical sociology, the basic conoulturc and so&t!, ccpls 01‘ the sister disciplines -hold the key. The anthropologist consciously and subconsciously. sees problems and data in a cultural context. while the sociologist sees them in a social context. A systems approach, a holistic view, the question, “How do these data fit into the whole picture?” underlies most medical anthropological rcscarch. The anthropologists begins his research by asking about the ethnic and cultural affiliation of the people concerned, about their beliefs and practices, their values and prcmiscs. The sociologist thinks first of social and class differences, of economic levels and standards of living, of role and status, of professions and professionalization, of dependent and independent variables. Although they research many of the same topics. the basic professional orientations of medical anthropologists and medical sociologists will be reflected in their approach to the problem, the data they gather. and the conclusions they reach. In the doctorpatient relationship, for example, the sociologist is concerned with status differences, the sick role and perhaps illness as a form of deviancy. The anthropo: logist. in contrast, sees cultural rather more than social differences as separating doctor and patient, and he emphasizes communication and perception problems, and the differing role expectations that stem from different cultural backgrounds. Both approaches are valid; both are important. From the two together, we learn more than from either one singly. And this. it seems to me, is the rationale for separate but allied medical behavioral science specializations. Precisely because we ask different questions. seek out different data and come to conclusions that reflect our professional biases, our total understanding of medical a.nd health phenomena I\ ricllc‘i- and mui-c varied than if the task were left to a single discipline. We are in complementary and not competitive. lines of work. We learn from each other and we teach each other. Our society needs both of us.

REFERENCES 1. Wax M. L. Sociolog\. In Anrhropolog_v and the Behaoioral and Health Sciences (edited by Von Mering 0. and Kasden L.) pp. 39-51. University of Pittsburgh Press. Pittsburgh. 1970.

431

2. Clements F. E. Primitive concepts

of disease. University of California Publications. In Amcricon Archurology and Ethnology 32. 185-252, Berkeley. 1932. 3. Bunzel R. The role of alcoholism in two Central American communities. Ps~xhiat. 3. 361. 1940; Demerath N. S. Schizophrenia among primitives. Am. J. Psych&. 98. 703. 194’; Devereaux G: Primitive psychiatry. Bull. Hist. Med. 8. 1194. 1940: 11. 522. 1942: Gillin J. Maeical fright. P.&hiat. 11, 387,‘1948; Hallowell A. I. C;lture and mental disorder. J. Ahn. Sot. Psycho/. 29. 1. 1934; Henry J. Anthropology and psycho‘somatics. PsTchosom Med. II. 216. 1949; Leighton A. H. and Lelghton D. C. Elements of psychotherapy in Navaho religion. Psychiut. 4. 515. 1941: Mead M. The concept of culture and the psychosomatic approach. Psychiur. 10. 57. 1947; Opler M. E. Some points of comparison and contrast between the treatment of functional disorders by Apache Shamans and modern psychiatric practice. Am. J. Psych& 92. 1371, 1936. 4. Devereaux G. The social structure of a schizophrenic ward and its therapeutic fitness. J. c/in. PsvchopafhoL 6. 231. 1944; Joseph A. Physician and paiient: some aspects of interpersonal relations between physicians and patients, with special regard to the relationship between white physicians and Indian patients. Appl. Anfhropol. 1, I. 1942: Leighton A. H. and Leighton D. C. The Navaho Door. Harvard University Press. Cambridge 1944: Schneider D. M. The social dynamics of physical disability in Army basic training. Ps~&iat. 10, 323, 1947. 5. Philips J. The hookworm campaign in Ceylon. Hands Across Frontiers: Case Studies in Technical Cooperarion (edited by Teaf H. M. jr. and Franck P.-G.)

265-305. Cornell Universitv Press. Ithaca. New York 1955. Caudill W. Applied anthropology in medicine. Anrhropology Today (edited by Kroeber A. L.) pp. 771-806. University of Chicago Press, Chicago 1953. Scotch N. A. Medical anthropology. Biennia/ Review of Anthropology 1963 (edited by Siegel B.) pp. 30-68. Stanford University Press. Stanford, California 1963. Straus R. The nature and status of medical sociology. Am. Social. Rec. 22. 200, 1957. Coe R. M. Sociology, qf Medicine p. 23. McGraw-Hill. New York, 1970. Freidson E. Prqfessional Dominance: The Social Structure of Medical Care p. 48. Atherton. New York. 1970. Freidson ibid. p. 48. Roth J. A. “Management bias” in social science study of medical treatment. Hum. Organizarion. 21. 47. 1962. Roth ibid. p. 4849. Glaser W. A. Medical care-II: Social aspects. Int. E!J~J~c/.Sot. Sci. 10, 95, 1968 (emphasis added). Clark M. Health in the Mexican-American Culture D. 215. University of California Press. Berkeley and Los Angeles. 1959. Becker H. S.. Geer B.. Hughes E. C. and Strauss A. L. Boys in w/&r,: Studrnr Culture in a Medical School p. 17. University of Chicago Press. Chicago. 1961. Becker et al.. ibid. p. 18. Olesen V. L. and Whittaker E. W. The Silenr Dialogue: PD.

6. I. 8. 9. IO. 11. 12. 13. 14. 15. 16. 17. 18.

A Stud!, on the Psycholog), of Prqfessional Socialization

19. 10.

21. 12. 23. 24.

p. xi. Jossey-Bass, San Francisco. 1968. Olesen and Whittaker. ibid. p. 19. Merton R. K. Some preliminaries to a sociology of medical education. The Srudenr Physician (edited by Merton R. K.. Reader G. G. and Kendall P. L.) pp. 3-79. Harvard University Press. Cambridge, 1957. Bloom S. W. Power and Dissent in t\7e Medical School p. 12. The Free Press. New York. 1973. Bloom. ibid. p. 12. Coe. op. cit. pp. 119-161. Freidson. op. cit. p. 10.

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25. Freidson, ibid. 26. Pellegrino E. D. Medicine, history and the idea of man. Med. & Sot. (Edited by Clausen. J. A. and Straus. R.): Attn. Am. Acad. PO/. Sot. SC;. 346, 10. 1963. 27. Pellegrino, ibid. p, IO. 28. Alland A. Jr. Medical anthropology and the study of biological and cultural adaptation. Am. AnthropoL 68. in Cultural Euoiution: ,411 40. 1966; Adupratiorl Approach to Medical Anthropology. Columbia University Press, New York 1970; Baker P. T. and Weiner

29. Livingstone F. B. Anthropologtcal implicattons 01 sickle cell gene distribution in West Africa. .-1n1. -Illr/zropol. 60. 533. 195s: Wisenfeld S. L. Stcklr cell tract in human btological and cultural evoiutton. S~~I~~IIC~~, 157. 1131. 1967. 30. McCracken R. D. Lactase deticiency : an eiamplc 01 dietary evolution. Cwr. .4urhropo/, 12. 179. 197 I