SUMMARY Early adversity has powerful effects on development that reach far into adulthood to affect health and survival. At the same time, social adversity in adulthood—particularly social isolation and low social status—is a strong predictor of poor health and survival. These important discoveries, now major topics in social science and medical research, highlight key questions about how early life adversity and adult social adversity are linked, and whether both directly affect survival. Notably, no studies have yet been able to unambiguously link real- time observations of early adversity to detailed data on adult social relationships, health, and survival in the same individuals; the relevant data are exceptionally difficult to collect within any single human population study. A nonhuman primate model is the most expedient way to overcome these barriers, and the time is ripe to develop such a model. Just as primates have long been used as models for cellular, physiological, and molecular mechanisms underlying human health and disease, they can serve as model systems for understanding social and behavioral processes in humans: a number of key studies have demonstrated that important social and behavioral processes are evolutionarily conserved between humans and nonhuman primates. The proposed research will contribute a novel nonhuman primate model of early adversity and lifespan. This proposed study population, a natural population of baboons, has been the subject on continuous research for over four decades and offers prospective, full life-course data, with real-time, direct observations of both early life adversity, adult sociality, and longevity. It sidesteps the complications of health habits and health care access that complicate studies in human populations, and greatly accelerates the timescale for collecting complete life history data, as the lifespans of wild baboons are about 1/3 the length of human lifespans. Three important scientific contributions are expected. First, if the study reveals, as hypothesized, that early adversity and adult sociality both exert independent effects on survival, the work will help shift current research from whether each phase of the life course exerts an influence, to how social behavioral mechanisms contribute to these influences (Aim 1). Second, the proposed study of adult relationships (Aim 2) will provide fresh insight into sources of resilience in the face of early adversity. Third, the proposed model of ‘adversity amplifiers’ (Aim 3) will formalize an idea that has just begun to crystallize in the adversity literature, stimulating new research avenues. In the aggregate, the work will produce the first complete worked example, in any study system, of the links between early life, adult life, and longevity. The results will help move the field forward by refining critical hypotheses, providing prospective answers to crucial questions, and pointing to the most fruitful avenues for research in diver...