Jacob Douglas Negrey

Social aging, broadly defined by waning social participation with advanced age, is widespread in contemporary human societies. Why social aging occurs remains unclear: Although biomedical research characterizes social aging as a nonadaptive outcome of functional (e.g., physical) impairment, some anthropologists and biologists offer adaptive explanations for social aging. Wild chimpanzees (Pan troglodytes) provide critical comparative data for understanding human aging processes given chimpanzees’ close genetic proximity to humans, intense social relationships, and human-like life expectancies. Here, working with an international team of collaborators, I propose to investigate age-related variation in social participation in a particularly long-lived population of wild chimpanzees living at Ngogo, Kibale National Park, Uganda. To assess both adaptive and nonadaptive hypotheses for social aging, we will also characterize age-related trajectories in physical function, cellular damage, and immune health using innovative observational methods and laboratory methods. To complement detailed cross-sectional analyses, we will leverage pre-existing data, including thousands of hours of behavioral data, to assess individual-level changes over ten years and determine the timing and rates of functional decline. Together, these data will advance our understanding of social aging by helping illuminate causal relationships between social and functional aging in our close relatives.