[Biological and social aspects of migration of the Andes population].

The effect of migration on the biology of human populations is almost unknown. While some studies of populations moving from areas which are poor and without medical care clearly show that movement into more prosperous areas improves general health, these studies fail to show the specific effects of changing physical environments. In the present study migrants from the altiplano of Southern Peru to the adjacent low altitude zones were examined. The data were compared to similar data on migrants from low altitude areas and native low altitude people. Preliminary analysis of the information collected suggested the following: 1. Adult women increase slightly their completed fertility when they move from high to low altitude. Child spacing is particularly decreased but birth sex ratios are not affected. 2. Highland migrants at low altitude produce larger newborns than they do at high altitude and these infants grow more rapidly than high altitude infants. 3. Migrants from high to low altitude suffer more respiratory symptoms than low altitude migrants or lowland natives. 4. Although highland migrants quickly adopt low altitude life styles and diets they do not show the age increases in blood pressure or high levels of serum cholesterol common in lowland natives. On the basis of these findings it is concluded that migration may have some detrimental effects on human health and physical fitness. However, more importantly they show that the specific physical environment in which an individual develops has a significant effect on the health fitness of a migrant to a new environment.