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A decades-long trend toward increasing life expectancy and greater lifespan equality in human populations raises the possibility that we can dramatically slow the rate of aging. But lifespan is affected by many different variables, and the evolutionary causes and genetic basis of variation in lifespan are debated. I will present summaries of several studies that illustrate diverse approaches to understanding the ecology and evolution of longevity, using the wild baboon population in the Amboseli basin of Kenya. First, I review a longstanding hypothesis about how the stress response affects lifespan, and I show how differences among female baboons in cumulative glucocorticoid concentrations over decades (measured noninvasively in fecal samples) predict differences in lifespan in this population. Second, I present evidence about the genetic basis of variation in lifespan among female baboons in the Amboseli baboon population, using a quantitative genetic approach known as the ‘animal model.’ We found measurable heritability for both annual survival and survival across the lifespan, suggesting that longevity has the potential to evolve in this population. Finally, I present data on the effect of age on female reproductive patterns, including the tendency for older female baboons to experience higher fetal loss rates and to produce more daughters. |