Other Titles of Interest ELLING, R. Traditional and Modern Medical Systems GISH, O. Crisis in the Public Sector KEEHN, J. D. The Ethics of Psychological Research KLEINMAN, M. B. Ethical Aspects of Access to Medical Care PYLE, G. F. New Directions in Medical Geography A Related Journal* SOCIAL SCIENCE & MEDICINE is the international forum for exchange of ideas and information among social scientists, medical researchers and practitioners, and health administrators and planners. Editor-in-Chief: Peter J. M. McEwan •Free specimen copy and subscription details available on request. CROSS-CULTURAL STUDIES OF BIOLOGICAL AGING Edited by CYNTHIA M. BEALL PERGAMON PRESS OXFORD · NEW YORK · TORONTO · SYDNEY · PARIS · FRANKFURT U.K. Pergamon Press Ltd., Headington Hill Hall, Oxford OX3 OBW. England U.S.A. Pergamon Press Inc., Maxwell House, Fairview Park, Elmsford, New York 10523, U.S.A. CANADA Pergamon Press Canada Ltd., Suite 104, 150 Consumers Rd., Willowdale, Ontario M2J 1P9, Canada AUSTRALIA Pergamon Press (Aust.) Pty. Ltd., P.O. Box 544, Potts Point, N.S.W. 2011, Australia FRANCE Pergamon Press SARL, 24 rue des Ecoles, 75240 Paris, Cedex 05, France FEDERAL REPUBLIC Pergamon Press GmbH, 6242 Kronberg-Taunus, OF GERMANY Hammerweg 6, Federal Republic of Germany Copyright © 1982 Pergamon Press Ltd. All Rights Reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means: electronic, electrostatic, magnetic tape, mechanical, photocopying, recording or otherwise, without permission in writing from the publishers. First edition 1982 ISBN 0 08 028946 0 Also published as Volume 16, Number 2, of the journal Social Science and Medicine and supplied to subscribers as part of their subscription. Printed in Great Britain by A. Wheaton & Co. Ltd,, Exeter Soc. Sei. & Med. Vol. 16. pp. 131 to 133. 19X2 0277-9536 82 020131-{)3S03.(H) 0 Printed in Great Britain. All rights reserved Copyright © 19X2 Pergamon Press Ltd INTRODUCTION "Like disease, aging follows different natural histories Massachusetts who survived childhood epidemics in different populations and in different historical subsequently survived longer than people who did not settings," writes a physician [1, p. 1]. To that state­ experience that stress. However, this survival advan­ ment the anthropologist would add "different en­ tage does not appear to be heritable. Borkan. Bach- vironments and different cultures". Until recently, man and Norris report that the chances of survival of physical anthropologists have not displayed particu­ individual men in the Baltimore Longitudinal Study lar interest in biological aging cross-culturally. Conse­ (U.S.) are influenced by certain lifestyle variables such quently, knowledge of the process of biological aging as smoking behavior and those factors that underlie in different environments and cultures throughout the health status and obesity. Variation in longevity, world and of the nature of normal human aging is not therefore, is examined in light of variation in environ­ well understood. The following collection of papers mental factors such as those that give rise to contrast­ represents a recent emergence of interest in these ing disease patterns and cultural factors such as differ­ issues. ent lifestyles. The majority of the papers in this volume were Modernization/acculturation and migration models presented at a symposium Physical Anthropological are frequently employed by anthropologists because Approaches to the Study of Biological Aging held at they can provide a natural experimental setting where the annual meetings of the American Association of only social factors vary while the genetic population Physical Anthropologists in April 1980. The papers and the physical environment are 'controlled for' use, in various forms, a basic model emphasizing (acculturation/modernization model) or where both interacting biological, cultural and environmental social and physical environmental factors vary while factors and they begin to provide needed data on the the genetic population in 'controlled for' (migration range of variation in certain biological processes pre­ model). The modernization/acculturation model is viously evaluated as normal aging from the perspec­ employed by Crews and MacKeen in a natural ex­ tive of industrial populations and Western biomedical periment that contrasts causes of mortality in tra­ knowledge. They also provide materials for re­ ditional and modernizing areas of Samoa. They indi­ evaluating elements of certain generalizations and cate that a very high prevalence of obesity in America theories about aging, also previously elaborated in Samoa, a concomitant of recent modernization, has terms of Western industrial society or over-simplistic been followed rather shortly by a high death rate due contrasts between Western and non-Western society. to diabetes mellitus but not cardiovascular disease. The papers utilize both longitudinal and cross-sec­ They suggest that a longer time must elapse before tional samples. They range over diverse types of data the sequelae of obesity are realized in terms of eleva­ including historical, demographic, genetic, morpho­ tion of the cardiovascular disease death rate. logical and physiological and come from a variety of Using a migration model to study Samoan areas including Scotland, the U.S., Nepal, Mexico, migrants to San Francisco, California. Pawson and Colombia, Papua New Guinea, The Solomon Islands, Janes examine some of the risk factors linked to mor­ and Samoa. Yet, despite the diversity of data, research tality from diabetes mellitus and cardiovascular dis­ sites and research design, several recurring themes ease. Migrants are more obese and have higher blood provide an integrating continuity. These themes per­ pressures than their counterparts who remained in tain to theoretical and methodological conerns fami­ Samoa. These biological changes plus the sociocul- liar both to gerontologists and physical anthropolo­ tural discontinuity experienced by the migrants con­ gists, namely: longevity, causes of mortality and mor­ stitute multiple interrelated health risks that may bidity, secular trends, morphological and functional influence age at and cause of death. change, physical activity, and the interdependency of It is of considerable interest to gerontological biological, environmental and cultural parameters. research to understand what normal aging is, in other Longevity and factors influencing longevity is words, what age-related changes are irreversible con­ approached at the population, the family and the in­ comitants of the passage of time common to the spe­ dividual level. Brennan employs an historical demo­ cies, what age-related changes are associated with cer­ graphic approach to address the population level tain environments, diseases, lifestyles, and cultures through an examination of the secular decline in (and therefore may be avoidable), and what factors crude death rates and the accompanying change in accelerate or slow age-related processes. Several of the causes of death between 1855 and 1974 in Sanday. following studies demonstrate the utility of cross-cul­ Orkney Islands, Scotland. Using a population gen­ tural comparisons in ascertaining the range of vari­ etics perspective, Crawford and Roberts demonstrate ation of these morphological and physiological pro­ no age-related differences in heterozygosity levels in cesses and the importance of considering the influence Mennonite populations in the U.S. contrary to the of cultural and environmental factors. They also dem­ predictions of earlier models. They also examine cor­ onstrate some of the pitfalls of this research design. relation coefficients for the age at death of Mennonite The nature and extent of morphological and func­ parents and offspring. At the individual level, Meindl tional change with age is shown to vary from popula­ reports that people in nineteenth century western tion to population and among individuals within 131 132 Introduction populations. The underlying factors are associated the importance of considering activity as a variable with secular trend, (e.g. Malina et α/.), migration with influenced by environmental and cultural factors. concomitant environmental and social change (e.g. Contrasts between traditional. Westernizing and Pawson and Janes), acculturation/modernization Western populations is another recurrent theme in (Freidlaender and Rhodes, Weitz), cultural differences these papers. Because of the vast scale and rapid rate in fertility behavior, activity patterns and lifestyle of modernization today and because it has an effect (Beall and Goldstein, Borkan et al. Malina et ai, on factors such as nutrition and activity thought to Friedlaender and Rhoads, Weitz). influence aging, this is an important issue for both The body constituent which demonstrates this vari­ medical and social scientists. The paper by Pawson ation most dramatically is fat. In Western society the and Janes examining four Samoan populations at amount of body fat undergoes major fluctuations dur­ increasing degrees of removal from traditional ing adulthood. There is an increase in weight in the Samoan culture and environment demonstrates pro middle years followed by a decrease in old age while gressively increasing degrees of obesity with those skinfold measurements of fat typically increase with furthest removed from the traditional being perhaps age until the seventh or eighth decade and then de­ the world's most obese population. In the Solomon cline [2]. The populations described in several of the Islands and in Papua New Guinea, new crops, occu papers depart from this pattern. For example, Malina pations and diet are important changes occurring et ai report that Zapotee Indian women in Mexico with acculturation which are reflected in changing remain relatively lean until the forties when they ex­ patterns of biological aging (Friedlaender and perience an increase in fatness followed by a decline. Rhodes). In Nepal, different household composition, A further variation is revealed by Friedlaender and caused by out-migration, is an important factor affect Rhoads using a semi-longitudinal design among tra­ ing the elderly. For example, in one Nepalese village, ditional villagers of Bougainville Island, Papua, New 73% of the people over the age of 70 live in one Guinea and Malaita Island, Solomon Islands where or two person households (Beall and Goldstein). women lose fat dramatically after a maximum in early According to one projection, the world's population maturity. Both sets of authors suggest that the re­ aged 65 and over will more than double between 1970 ported pattern may be related to the energy demands and 2000 to reach an estimated 396 million of which of successive periods of pregnancy and lactation. How­ 230 million (58%) will live in the developing countries ever, Friedlaender and Rhoads also report that in [4]. rapidly modernizing villages, female fatness increases It is also possible to consider the importance of the dramatically during adulthood although fertility does timing of certain cultural and environmental not change, indicating that childbearing alone may influences by using a broad, lifespan perspective. not be responsible or that other changes associated Meindl and Mueller both demonstrate that events at with modernization overrride the eñ'ects of childbear one point in the life cycle may be critical for under ing. Thus the manifestation of what is described as an standing subsequent events. Meindl refers to child 'aging phenomenon* in Western industrial society is hood morbidity and adult mortality and Mueller dependent, at least in part, upon factors other than refers to periods of rapid change in fatness and fat the passage of time. patterning during adolescence and young adulthood Activity patterns are given a prominent role in a and suggests that these may be sensitive periods for well known theory regarding the rate of biological developing a predisposition toward one or more of aging [3]. The interaction of activity patterns and the chronic degenerative age-dependent diseases morphological and physiological factors is characteristic of western populations. The concept of approached from two different perspectives. Weitz a sensitive period has been useful in studies of child shows that Tibetan migrants living in a low-altitude, growth and development and may prove useful in urban environment and engaged in sedentary occupa aging studies also. A perspective encompassing the tions have higher resting systolic blood pressures and entire lifespan facilitates studies of the relationships a greater increase in blood pressure with age and a between aging and earlier stages of the life cycle. smaller increase when exercising than Tibetan A few papers deal with the recurrent methodologi migrants and Sherpas living in high-altutude, rural cal difficulty of separating aging effects from those of villages. Indeed the high-altitude residents studied by secular trend. For example, are younger adults taller Weitz as well as those studied by Beall and Goldstein than the elderly because the former achieved greater exhibit very little age-related increase in blood press mature stature, the latter have lost stature, or both? ure. While there is a contrast in the activity patterns This is dealt with indirectly in cross-sectional studies of the high and low altitude samples, the simul by statistical manipulation (Malina et ai) and induc taneous altitude and rural-urban contrasts confound tive reasoning (Beall and Goldstein) and directly, and the comparison and it is not possible to isolate the most powerfully, by the use of a semi-longitudinal effects of activity in these samples. Beall and Gold design (Friedlaender and Rhoads). stein note that morphological and functional decline The quest for an overall measure of aging has occu do not necessarily result in changing daily activity pied many researchers. Borkan et al consider this patterns among rural Helambu Sherpas at high alti issue using two measures, visual and physiological, tude in Nepal. Friedlaender and Rhoads note that and discuss some of the reasons for the difficulty in activity patterns change upon modernization and attaining or developing an overall measure. An im speculate that these may play a role in the accompany portant reason may be that our still somewhat limited ing morphological changes. These data certainly do data base and concept of what aging is derived largely not disprove the importance of activity in influencing from western industrial populations. Suggestions and aging or age-related processes and they do indicate hints of directions for research in our own and other Introduction 133 cultures and environments are contained in each of REFERENCES the following papers. It is generally agreed that the quality of life of the elderly is an important consideration and one which 1. Ostfeld A. M. Introduction and summary. In Epulemi- ology of Aging (Edited by Ostfeld A. M., Gibson D. C. depends in part upon the actual biological changes and Donnelly C P.), p. 1. USDHEW, Maryland, Pub­ with age, but, also upon the cultural setting in which lication No. (NIH) 77-711, 1977. these occur. It is the explicit awareness of this in 2. Rossman I. The anatomy of aging. In Clinical Geri­ designing and executing research, illustrated by these atrics, 2nd edn (Edited by Rossman I.), p. 3. Lippincott. papers, that provides the anthropologist with a Philadelphia, 1979. unique and useful perspective that may further both 3. Leaf A. Unusual longevity, the common denominators. anthropological and gerontological research. Hosp. Prac. 8, 75, 1973. 4. Häuser P. M. Aging and world-wide population Department of Anthropology, CYNTHIA M. BE ALL change. In Handbook of Aging and the Social Sciences Case, Western Reserve Universitw (Edited by Binstock R. H. and Shanas E.), p. 74. Van Cleveland, U.S.A. Nostrand Reinhold, New York, 1976. Soc. Sei. ά Med. Vol. 16. pp. 135 to 140. 1982 0277-9536 82 020135-06S03.00 0 Printed in Great Britain. All rights reserved Copyright © 1982 Pergamon Press Ltd BIOLOGICAL FUNCTION, ACTIVITY AND DEPENDENCY AMONG ELDERLY SHERPA IN THE NEPAL HIMALAYAS CYNTHIA M. BEALL and MELVYN C. GOLDSTEIN Department of Anthropology, Case Western Reserve University, Cleveland, U.S.A. Abstract—This paper considers a model contrasting the aging experience of Western and non-Western populations through consideration of the hypothesized interrelationships among four factors (biological change with age, dependency, family structure and the aging experience) in a non-Western setting. Western views of the contrast in the aging process in Western industrial and traditional pre-industrial societies include the notion that traditional societies manifest relatively slow rates of biological aging, and have extended family structures which accommodate the elderly resulting in few aging problems. On the basis of data deriving from a case study of Sherpas in Helambu. Nepal, the model appears to be an oversimplification and suggestions for revision are offered. INTRODUCTION that the traditional family structure accommodates the elaerly in routine and satisfying ways since in the Biological aging takes the form of morphological normal course of the family cycle, one or more adult involution leading to a gradual decline in the per­ children remain in the parental household, assume formance of individuals[l]. The rate, causes and con­ productive responsibilities, and provide needed sup­ sequences of this involution are major questions for port to aging parents. These inconsistent views the science of gerontology and ones which assume require investigation and perhaps revision. The pur­ ever greater importance as the numbers of people pose of the present paper is to report some results of a living to long chronological ages increase globally. In study addressing these issues in a traditional society the quest for solutions to the aging problem in devel­ through systematic consideration of the components oped countries we have occasionally sought infor­ of the model. mation from traditional societies. Despite a paucity of systematic study, several ideas about aging in tra­ ditional non-Western societies grew and persist. These MATERIAL AND METHODS are summarized in the model presented in Table 1. A central component of the model is the explicitly and Sample frequently stated concept that a state of dependency is Sherpa society represents an excellent setting to universal among the elderly[2-4]. This stems from the examine these issues. Sherpas are a Tibetan speaking, reasoning that physical capacity declines as aging Buddhist population inhabiting rugged mountainous progresses and results in a decline in an individual's areas in Nepal. The data were collected over a 6-week capability to be a self-supporting member of society. period during July-August 1979 in the contiguous He must then receive goods and services from others Sherpa villages of Norbugyang and Pemagyang to survive, that is, become dependent. This state of (pseudonyms) situated at an altitude of 28(X)m, in dependency is viewed pejoratively and is considered Helambu, an area two days' walk from Kathmandu. the basis of many facets of the aging problem in Together these villages contained 75 households and Western society. 279 residents. On the other hand, some scholars postulate that Norbugyang and Pemagyang are rural agricultural the aging process poses no problem for traditional communities where the mode of subsistence and diet societies. They cite two reasons. One is that people in remain traditional. A census of the villages revealed traditional societies retain their faculties and physical that 28% of the residents are over 45 and 11% of the fitness longer due to a slower rate of loss and lack of residents are over 60 years of age. It is possible to debility and senility that results from maintaining obtain accurate Western chronological age estimates their productive social and economic roles and living from Sherpas because they use the traditional Tibetan in rugged environments[5]. A second reason argues system of naming years in a 60 year cycle. Individuals Table 1. Western concepts of the contrast in the aging process between Western industrial and tra­ ditional pre-industrial societies Relative rate of Degree of dependency Society biological aging in elderly Family structure Aging problems Traditional. Slow High Extended No pre-industrial Western. Fast High Nuclear Yes industrial 135 136 CYNTHIA Μ. BEALL and MELVYN C. GOLDSTEIN know their named birthyears which are easily trans­ was calculated from the regression equations. For this posed into a Western date of birth. same set of measures, the change per decade was cal­ Sampling for the study began with persons aged 45 culated for Western population samples by using the and over for two reasons. This is the youngest age at published sample means. The mean value of the which Sherpas would have adult children upon whom measurement at the later age was expressed as a per­ they could rely if necessary. This is also the decade cent of its value at the younger age, and a rate of when many functional and anthropometric measure­ change was obtained by dividing the percent change ments begin to change with age[6]. The sample, con­ by the number of decades. Western samples whose sisting of 43 persons, represents 60% of the popula­ upper and lower ages were as close as possible to 40 tion over 45 and all but 5 of the 29 residents over 60. and 80 years of age were selected so as to cover the The average age of the 19 males is 61 and of the 24 same age span as the Sherpa sample. Relative rates females is 62 years. These subjects provided several rather than absolute values of change were employed types of information including (1) anthropometric and in order to standardize the data for comparison pulmonary functional measurements taken according between populations of very different young adult to standard protocol[7], (2) activity and dietary infor­ body size. mation obtained through previous-day recall inter­ A second analytic approach measured variation in viewing, and (3) demographic data pertaining to fer­ biological age within the population. It assessed an tility history and household composition, and (4) individual's (or a sub-population's) biological age cultural information concerning definitions of aging, relative to his chronological age peers by utilizing the perceptions and evaluations of the elderly's situation, standardized residual score of each of the age related and Sherpa social and economic structure. variables for each individual[8]. The residual rep­ resents the individual's departure from the regression estimated population mean at that age. For negatively sloped characteristics such as height, a negative resi­ ANALYSIS dual indicates that an individual's height lies below The study sought to measure biological aging by the population mean and in this particular context measuring a range of morphological characteristics will be interpreted to indicate that the individual has reflecting underlying morphological involution and at a relatively greater biological age. So that older indi­ some level, presumably functional capacity. A group viduals have greater scores, the standardized residuals of anthropometric measurements reflecting par­ of negatively sloped characteristics were multiplied by ameters which show age related variation among negative one. some Western populations was taken. Correlation- Applying this procedure to each of the age related regression analysis permitted testing the hypothesis characteristics for each sex, a biological age profile for that these change with age in the non-Western Sherpa an individual or a group may be constructed[8]. In population. This provided a means of comparing age this case, differences in the relative biological ages of differences among the Sherpas with those among (1) elderly people living alone, (2) elderly couples and samples drawn from Western industrial populations. (3) those in extended families, were examined using a For those measures which change with age in the one-way analysis of variance. Thus the association Sherpa population, the percent change per decade between an individual's biological age profile, used as Table 2. Percent change per decade in morphological measurements significantly correlated with age (P < 0.05) among adult male Sherpas, Helambu, Nepal compared with those in Western samples (the regression coefficients with age and their standard errors are indicated) Percent change Percent change per decade in per decade in Sherpa sample, western samples Age calculated from calculated from Measurement b ± SE, regression equation published means Sources Weight -0.42 ± 0.28 -3.3% -1.2% to -5.4% [10-14] Height -019 + 0.49 -1.1% -0.7% to -1.0% [11-13] Sitting height -021 + 0.07 -2.4% -0.08 to -1.4% [10-12] Transverse -0.04 ± 0.03 -1.5% -03% [12] chest diameter Upper arm -015 ± 0.48 -5.8% -2.0 to -3.4% [12,15] circumference (left) Grip strength -0.62 + 0.10 -25.0% -6.6% to -14.7% [11 (preferred (right hand) hand), 12,16] Grip strength -0.51 ±0.13 -3.5% -6.6% to -13.8% [11 (preferred (left hand) hand), 12,16] Forced vital -O04 ± O02 -12.9% -18.6% [14] capacity Biological function, activity and dependency among elderly Sherpa 137 Table 3. Percent change per decade in morphological measurements significantly correlated with age (P < 0.05) among adult female Sherpas, Helambu, Nepal compared with those in Western samples (the regression coefficients with age and their standard errors are indicated) Percent change Percent change per decade in per decade in Sherpa sample. western samples Age calculated from calculated from Measurement b±SE, regression equation published means Sources Height -0.44 ± 0.10 -2.8% -0.5% to -1.5% [10,11,17-20] Sitting height -0.22 ± 0.06 -2.7% -1.0% to -1.7% [10, 11,17] Iliac height -0.22 + 0.07 -2.4% Biacromial -0.08 ± 0.03 -2.5% -1.0% to -1.1% [10,17] width Armspan -0.37 + 0.11 -2.3% + 0.5% [18] Grip strength -0.23 ± 0.07 -23.7% -6.4% to -13.0% [11 (preferred (left hand) hand) 16, 20] an indirect measure of functional dependency, and Sherpa males[l 1-14]. A similar pattern exists among family structure is tested. females. In several Western samples, height declines between 0.5 and 1.1% per decade compared to 2.7% among Sherpa females[ll, 15,17-20]. RESULTS With regard to the family structure aspect of the The portion of the model contrasting relative rates model, a striking finding is that 10 of the 75 house­ of biological aging is considered using anthropo­ holds in these villages contained a sole person, rang­ metric and functional measures. Among the more ing in age from 59 to 87. Among the 11 2-person than two dozen measures, 8 are significantly corre­ households, 8 are elderly couples. 60% of the popula­ lated with age among Sherpa males between the ages tion over 60 and 73% of the population over 70 live in of 45 and 84. Several of these are themselves corre­ one or two person households. Among these, only one lated, for example, sitting height and height. Table 2 unmarried man and one unmarried woman (a nun) presents the change per decade in a variable by pre­ have no children. All others have at least one surviv­ senting the percent difference in the anthropometric ing child; 9 have surviving sons. It is therefore theore­ variables between individuals born ten years apart. tically possible for virtually all these individuals to be This is calculated from the regression equations of the living with adult children. 8 measures: weight, height, sitting height, transverse The hypothesis that those living in extended fami­ chest diameter, left upper arm circumference, right lies are doing so because their aging processes have and left hand grip strengths and Forced Vital Ca­ progressed more rapidly and they are therefore more pacity (FVC). 'dependent' due to greater loss of function is tested by Table 3 presents analogous information for the 6 examing their biological age profiles compared with measurements significantly negatively correlated with elderly living alone or as a couple. Biological age pro­ age among female Sherpas aged 45-87. These are files utilizing the age-related characteristics were con­ height, iliac height, sitting height, biacromial diam­ structed for 3 subpopulations of elderly Sherpas: eter, armspan and left hand grip strength. those living in single person households, in 2-person Some measures such as systolic and diastolic blood housholds and in households of 3 or more people. pressure; bi-iliac diameter, triceps and sub-scapular These are illustrated in Fig. 1. There is no statistical skinfold measurements which do change with age in difference in the average biological age among the other populations do not do so among the Sherpas. sub-populations in any parameter comprising the There is a borderline association between systolic profiles nor is there a consistent pattern difference. blood pressure and age among females. Although the average female systolic blood pressure in this sample is 112 mm Hg, two females in their seventies have DISCUSSION systolic blood pressures greater than 160 mm Hg. This yields a systoHc hypertension frequency of 25% Data examining the various components of a model among females aged 65-74 compared with a U.S. fre­ contrasting the aging processes of Western and non- quency of 46.9%[9]. Western populations were presented. With regard to For those measures significantly associated with biological aging in Western and non-Western popula­ age, comparison of the percent decline per decade tions, two general results were obtained. Supporting manifested in the Sherpa sample and in several the hypothesis that Western and non-Western aging Western population samples indicates that they are are dissimilar, as the standard model proposed, is the very similar (refer to Tables 2 and 3). For example, finding that many of the parameters measured do not height declines between 0.7 and 1.0"o per decade vary significantly with age among the Sherpa, for among several samples of Western males compared to example, bi-iliac diameter, subscapular and triceps 1.1% among Sherpa males[ 11-13]. Weight declines skinfolds and blood pressure. Therefore, certain between 1.7% and 5.4% per decade among several features identified as normal aging on the basis of samples of Western males compared to 3.3% among Western experience may not be inevitable concomi- 138 CYNTHIA Μ. BEALL and MELVYN C. GOLDSTEIN BIOLOGICAL AGE BIOLOGICAL AGE o I Γ -Ί 1 I Γ "Ί Height Weight Iliac weight Height Sitting heigh Sitting height Transverse chest Biacromial width diameter Upper arm Arm span circumference right grip Left grip strength strength Left grip strength FVC Household size 1 person 2 people 3 people Fig. 1. Biological age profiles of elderly Sherpa living in households of one, two and three or more people. tants of the passage of time. This demonstrates the among Sherpa women. One may speculate that both need for future research to measure a wide range of aging and secular trend are manifested by female phenomena cross-culturally in order to uncover pat­ Sherpas. Larger samples of women including younger terns of association and constellations of features women and more detailed knowledge of local history which change together or independently within and to ascertain changes which could have produced a between different populations. secular trend are necessary to strengthen the argu­ Arguing against the hypothesis that non-Western ment which in any case remains indirect so long as it and Western aging is dissimilar is the finding that rests on a cross-sectional sample. among the variables which do change with age such While the rough techniques used for comparison in as height and sitting height, the change occurs among this paper require refinement in future research, over­ the Sherpas at about the same rate per decade after all the Sherpa findings suggest both similarities and the age of 40 as Western samples. The somewhat contrasts between the experience of biological aging greater age related decline among the Sherpas in Western and non-Western populations. reported in Tables 2 and 3 may reflect the different The model in Table 1 includes a dependency com­ method of calculating the percent decline. Since the ponent which is considered in detail in Beall and rate of aging accelerates with age[6,21] the slightly Goldstein[22]. This component will be examined older Sherpa sample may also account for this find­ briefly here from the biological perspective. Two sets ing. It is the case that the oldest age categories for of data are available to examine the idea that depen­ many of the published Western samples were in the dency increases with age. These are the biological age 70's. profiles and recall activity interviews. An important The change in some characteristics may be an arti­ issue is to determine to what extent age related bio­ fact of secular trend rather than aging. Separating the logical change affects the ability to provide for one­ possible effects of aging from secular trend is prob­ self. It is possible that those biologically the oldest lematic in a cross-sectional sample. One approach have lost function to the degree that they must relies on the observation that long bone length does depend on others for goods and services (see [22]). not shorten with age and does reflect secular Alternatively, aging people may simply lose their trend[18-21]. Two measures available for this sample, reserves of function above that normally used so that iliac height and armspan, reflect primarily long bone while function declines with age, it does not result in length. The lack of age differences in these two dependency, i.e. it does not require receipt of goods measures among male Sherpas is indirect evidence and services and residence with children or others. that secular trend may not have occurred. The decline The data show that on the basis of the biological in sitting height which contributed to the statural de­ aging profiles, it is not the case that those living alone cline therefore may be a time related phenomenon or with a spouse are the youngest biologically. Con­ reflecting shrinking of the intervertebral discs[6,21]. versely, those who are hving with other family The situation differs among female Sherpas. The members are not the oldest biologically. greater armspan and iliac heights among younger The second set of data derives from recall activity Sherpa women may reflect secular trend in length of interviews with 30 different people over the age of 50 the long bones. However, the decline in biacromial obtained on 15 different days during the peak agricul­ width also contributed to the decline in armspan tural season which yielded a total of 69 person-days