The proposed study uses a prospective, longitudinal design to study the effect of the social context on age at maturity in the Dogon of Mali. Age at maturity is a key life history trait because it has a profound impact on genetic fitness (Stearns 1992). Overall, the significance of the proposed study is that it will test three novel hypotheses, grounded in life history theory, each of which has the potential to transform theory in evolutionary anthropology, psychology, and public health.