The Aymara of western Bolivia: V. Growth and development in an hypoxic environment.

Abstract

As a part of the Multinational Andean Genetic and Health Program, the Bolivian Health Survey sought to compare the anatomic, physiologic and biochemical characteristics of Aymara of the Bolivian altiplano (3700-4000 m) to those of Aymara of the Chilean altiplano (4000-4500 m). Presented here are the anthropometric age changes and differences that accompany sex, ethnicity and permanence of residence. Our objective is to assess what physical growth differences, if any, obtain among populations residing in high regions. In height, weight and chest morphology, the two high altitude populations were more similar to each other than either was to a lowland control from the Chilean coast. The high altitude samples tended to exceed coastal controls in some of the chest measurements in spite of a generally smaller body size. This provides support for the idea that hypoxia may induce growth of anatomic features associated with oxygen transport. The two high altitude groups differed in some soft tissue measurements, and this difference was greatest among adults of the samples. These anthropometric differences probably reflect socioeconomic variation among populations at high altitude. Regional differences in environmental factors on the altiplano could influence the outcome of comparisons made between altitudes, and may account for a lack of consistent results among previous studies of the effects of hypoxia on human development. The effect of hypoxic environment on human growth has been studied in high altitude (over 3000 m) populations in South America (Hurtado, 1932; Frisancho and Baker, 1970; Mueller et al. 1978a), Ethiopia (Clegg et al. 1972) and the Himalayan region (Pawson, 1976; Malik and Singh, 1978). A basic requirement of such studies has been to identify a control population at low altitude of similar ancestry, environmental circumxThis work was supported by grants HL 15614, GM 19513 and CA 19311 from the National Institutes of Health. 2University of Texas Health Science Center, School of Public Health, P.O. Box 20186, Houston, Texas 77025. 3University of San Andres, La Paz, Bolivia. 4Universidad de Chile, Departamento de Biologia Celular y Genetica, Casilla 6556, Santiago 7, Chile. 5University of Texas Health Science Center, Center for Demographic and Population Genetics, P.O. Box 20334, Houston, Texas 77025. Human Biology, September 1980, Vol. 52, No. 3, pp. 529-546. ® Wayne State University Press, 1980 This content downloaded from 207.46.13.128 on Wed, 07 Sep 2016 04:24:33 UTC All use subject to http://about.jstor.org/terms 530 W. H. Mueller et al stances (excepting hypoxia) and historical antecedents. Also the effects of altitude on measurements of interest must be judged statistically against an appropriate error variance, usually taken to be the within-altitude variation. The latter has not really been evaluated in previous growthhypoxia studies by comparisons of populations residing at the same altitude. This would provide baseline information on biologic variation within altitude and help us evaluate the biologic significance of changes in physical growth between altitudes. Data on high altitude populations would be particularly important, because if hypoxia has an effect on human development, patterns of growth of high altitude populations should be similar. Frisancho et al. (1970) investigated this problem in Peruvian Quechua boys. Nunoa boys from the south (4000 m) were taller and had greater cortical bone areas (second metacarpal) than Vicos boys from central Peru (3000 m). Frisancho et al. (1970) interpret these differences as indicating better diet and living conditions in Nunoa. However, they point out the Nunoa data were collected eight years after the Vicos materials. Thus, whether the observed changes are due to regional differences or to secular changes in the environment over this time period is unclear. During the course of a multidisciplinary study of the health of the Aymara of northern Chile and western Bolivia, data were collected at various sites on both the Bolivian and Chilean altiplano region (3700-4500 m). It is the purpose of this paper to compare the physical growth of Bolivian and Chilean Aymara populations at high altitude to assess what differences, if any, obtain among populations residing in high regions. Materials and Methods The investigation described here is part of a larger study, the Multinational Andean Genetic and Health Program, initiated in Chile in 1973 (Schull and Rothhammer, 1977). Broadly stated, the objective of this study was to evaluate the effects of environmental differences, particularly oxygen tension, on pulmonary function, cardio-pulmonary relationships and degenerative cardiac disease in the Aymara; and to assess the genetic contribution to their anatomic, biochemical and physiologic responses. It became apparent in the implementation of these objectives that the Chilean altiplano was somewhat different from much of that in Bolivia and Peru. It is generally higher, though possibly not significantly so from the adaptational standpoint. It is also drier, the bearing capacity of the land This content downloaded from 207.46.13.128 on Wed, 07 Sep 2016 04:24:33 UTC All use subject to http://about.jstor.org/terms Growth of Bolivian Aymara 531 seems less, and the population is sparser. Cereal and potato cultivation are more limited in Chile. There are differences moreover, in settlement patterns which may influence behavior, and ultimately, disease and disability. It seemed prudent therefore to study villages in the Bolivian altiplano as well. The Bolivian phase was conducted in April 1975 in the Departamento de Oruro in the villages of Turco (3980 m) and Toledo (3752 m). A Turco village census lists 314 persons. The town has primary and intermediate schools and a clinic staffed by a nurse. Toledo and inclusive hamlets, with a population of 7000 persons, is served by a primary, a secondary and a high school; a church with resident priest; a water supply hand drawn from a collective system of open wells; and regular truck and mail service. The two villages appear to be genetically homogeneous as measured by biochemical and immunologic genetic markers (Ferrell et al. 1978). Residents of these communities are socio-culturally heterogeneous. Some are non-Aymara, that is, claim only Spanish or at least European antecedents; many are Aymara (see Tschopik, 1963), but more still are considered Mestizos or Cholos. The latter expressions are used indiscriminately to characterize not only individuals of mixed Indian and nonIndian ancestry, but often also upwardly socially mobile Aymara who have adopted Spanish customs, conventions and names. Thus, while the categories, Aymara and non-Aymara, have some biologic meaning, the terms Mestizo and Cholo identify a more uncertain group of individuals. Indeed, data on inherited biochemical and immunologic markers suggest the Mestizos to be appreciably more Aymara than non-Aymara (Ferrell et al. in press). Our assessment of an individual's origins was essentially sociologie; it rested entirely upon his or her patrinym and matrinym and where available, the patrinym and matrinym of his or her mother and father. The algorithm has been described elsewhere (see Schull and Rothhammer, 1977; Diaz et al. 1978). It tends to under-represent the Aymara, a number of whom will be classified as Mestizos, if their normal array of names is incomplete, or if as is frequent in Bolivia, they consciously adopt Spanish names to obscure their origins. Residential histories were taken on each subject. Those claiming to have lived all of their lives at high altitude are designated permanents. Those who had spent at least one year at a lower altitude (usually sea level) are designated non-permanents. The distribution of the sample by age, sex, ethnicity and residence is given in Table 1. Most on the Bolivian altipiano are either Aymara or Mestizo, and practically all indiThis content downloaded from 207.46.13.128 on Wed, 07 Sep 2016 04:24:33 UTC All use subject to http://about.jstor.org/terms 532 W. H. Mueller et al