Regression analyses of primate life spans on recently revised female body and brain masses of Old World primates predict a human life span of between 72 years and 91 years-estimates that exceed the age of human menopause (and prior estimates) by well over 20 years. The life spans predicted from body and brain sizes in the early Homo suggest that postreproductive life spans predate Homo sapiens Among anthropoid primates, residual longevity after body and brain effects are controlled is greatest for Homo and for the New World monkeys of the genus Cebus. Body and brain masses predict a 25-year life span for Cebus, although recorded life spans exceed 50 years. Cebus are geographically widespread, have a female-bonded social organization convergent with Old World monkeys, and are primarily frugivorous, though the diet is heavily supplemented with vertebrate prey. Regressions of phylogenetically independent contrasts indicate that body mass and brain mass relationships to longevity remain significant when phylogeny is controlled and that brain mass is a more robust predictor than body mass. These data are new in terms of the completeness of species representation, more reliable body masses, presentation of various comparison group regressions, and control for phylogenetic independence.