Sex, health and survival

Amboseli baboons

Sex differences in health and survival in a wild primate population

Sex differences in health and survival during aging are major topics of interest in medicine, epidemiology, demography and evolutionary biology. Despite this pervasive interest, and despite a wealth of data on aging in humans and a few well-studied model organisms, patterns of aging in wild animals remain largely undescribed. Studies of aging in wild animal populations, especially in our primate relatives, offer great potential benefits for our understanding of aging in humans. They can provide a comparative perspective on human aging, generate new questions, produce insights into the answers to old ones, and identify opportunities for alleviating the adverse consequences of aging.

Our goal is to fill significant gaps in our knowledge of aging in the wild in order to realize some of these potential benefits. Specifically, we will examine age-related changes in health and survival, and sex differences in these age-related changes, in the Amboseli baboons. Our motivating question is the survival-health paradox, the phenomenon observed in modern human societies in which women experience greater longevity and yet higher rates of disability than men. It is not known whether the health-survival paradox pertains in wild animal populations. Here we hypothesize that it does pertain, and that many of the same factors that affect survival and health in humans have parallels in wild primates, in spite of important social and physical differences between species.

Building on the long-term data of the Amboseli baboon population, we will examine individual patterns of survival and health. We will provide the first detailed description of sex differences in senescence in a wild primate population. Our analyses will focus not only on decline in survival with age (demographic senescence), but also on changes in health and function with age. In pursuing our research aims we will identify sex differences in behaviors that create risks, sex differences in the effects of risk factors, and sex differences in the stability and congruence of measures of function. Taken together, our analyses will enable us to identify the nature and causes of the survival-health paradox in wild primates, and by extension in humans.