Melissa Emery Thompson: University of New Mexico

Among the most dramatic changes to occur during human evolution were those affecting our life history. The evolution of the human fertility pattern, including relatively fast birth rates, overlapping offspring dependencies, and extended postreproductive life, remains an active area of research and debate that can be greatly informed by structured comparisons to the living apes. To do so effectively, we need high quality data from natural populations, as well as more detailed information about the physiological mechanisms that regulate fertility in both species. To that end, I will discuss empirical data on reproductive lifespan, determinants of fecundity, regulation of the interbirth interval, and parental investment in wild chimpanzees with comparison to human populations. Humans and chimpanzees share remarkably similar patterns for the regulation of fertility. Despite the relatively higher cost of human infants, human mothers appear less constrained by their reproductive systems than are chimpanzee mothers. These data support the view that the social context of reproduction has been a fundamental contributor to changes in life history.