CAREER: Life history transitions among the Toba in northern Argentina

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Human life history is characterized by single births, large offspring, delayed maturation, relatively short inter-birth intervals, and a long post-reproductive lifespan. During human evolution, childhood and adolescence were added as new life history phases to the characteristic life history of social mammals. The transition from one life history phase to the next, e.g. from infancy to childhood or from reproductive to post-reproductive life, represents a physiological challenge that can be conceptualized as a trade-off. This project evaluates the interaction among biocultural variables underlying key life history transitions and identifies and describes the implicated trade-offs. The project takes place in an indigenous community (the Toba) in the province of Formosa, Argentina. Biological and ethnographic data are collected to evaluate the somatic, developmental, cultural, and hormonal correlates of three life history transitions: infancy-childhood, puberty, and menopause. Longitudinal anthropometric and demographic data collected since 1997 are combined with new quantitative and qualitative information to achieve the following objectives: 1) extending the longitudinal database by collecting village-wide anthropometric and life history event data annually for five years; 2) exploring the transition from birth to complete weaning using data on children's growth trajectories, development, nutrition, and health; 3) characterizing the pubertal transition in girls by analyzing data on growth, maturation, health, and hormonal changes; and 4) characterizing the menopausal transition by analyzing data on anthropometric, health, and hormonal changes at the end of women's reproductive life. Ethnographic data will provide crucial information on the cultural meaning of these transitions for the Toba and how this meaning interacts with biological processes.Results from this research will contribute directly to issues of evolutionary development biology, the biodemography of aging, and clinical medicine, as it relates specifically to patterns of child growth and women's aging. The project also promotes education in science for U.S. and Argentine undergraduate and graduate students, particularly women and minorities through direct participation in research activities.