The Demographic Structure of Work and Intergenerational Transfers in an Amazonian Population

Paul L. Hooper, University of New Mexico
Hillard S. Kaplan, University of New Mexico

Evolutionary demographic models suggest that the long human post-reproductive lifespan can be understood on the basis of older individuals' contributions to fitness through transfers. Thus far, however, detailed studies examining the motivations for and magnitude of these transfers in traditional subsistence societies have been lacking. In this paper, we present results from a new analysis of economic and social behavior among native South Americans, the Tsimane of lowland Bolivia. These results show that Tsimane young remain in net caloric deficit until around age 20, but that the surplus production of post-reproductive men and women is substantial even when mortality is taken into account. There is evidence that adult productivity is motivated in part by the caloric needs of descendent kin. Quantitative estimates of caloric transfers within extended families indicate that net transfers are consistently downward across generations, and patterned according to age, sex, and dependent need.