Post-reproductive longevity is a robust feature of human life and not only a recent phenomenon caused by improvements in sanitation, public health, and medical advances. We argue for an adaptive life span of 68-78 years for modern Homo sapiens based on our analysis of mortality profiles obtained from small-scale hunter-gatherer and horticultural populations from around the world. We compare patterns of survivorship across the life span, rates of senescence, modal ages at adult death, and causes of death. We attempt to reconcile our results with those derived from paleodemographic studies that characterize prehistoric human lives as “nasty, brutish, and short,” and with observations of recent acculturation among contemporary subsistence populations. We integrate information on age-specific dependency and resource production to help explain the adaptive utility of longevity in humans from an evolutionary perspective.