October 23, 2017

Do Costs of Reproduction Affect Human Survival?

Michael Gurven, University of California, Santa Barbara

Sex differences in human mortality and health are widely documented in both low and high income countries. Usual explanations focus on differences in intrinsic senescence, lifestyle, and health-seeking behaviors. Another possibility is that costs of reproduction unique to women may alter their physical condition in adulthood relative to men. Additionally, variability in the intensity of reproductive effort may account for health-related phenotypic differences among women. The underlying logic behind these propositions assumes a simple trade-off given a limited energetic budget where investments in reproductive effort subtract from those affecting maintenance and survival. In this talk, I develop and explore these ideas by assessing sex differences in adult health and physical condition among small-scale, natural fertility populations of hunter-gatherers and horticulturalists. I then attempt to uncover the effects of reproductive intensity on women’s health among Tsimane Amerindians – an attempt rife with the usual methodological obstacles due to self-selection and the absence of randomization. I discuss implications in light of social environmental context and declining fertility worldwide.