Social influences on aging in a wild cooperative mammal

A key goal of research in biological and medical science is to understand why some individuals in a population remain healthy into old age, whereas others decline rapidly and die early. Research on model laboratory organisms such as fruit flies and mice suggests that the rate of decline in bodily function with age, or the rate of senescence, will depend on how individuals allocate resources to survival versus reproduction across the lifespan, and on the quantity and quality of resources available during growth and development. In highly social or cooperative animals, both these factors are strongly dependent on an individual's social status and its interactions with other group members. Our research will test for the first time the influence of these social factors on rates of aging and physiological senescence in a highly social, mammal, the banded mongoose, using a combination of long-term data analysis, behavioural experiments and physiological measures of senescence. Specifically we will address questions: (1) how does variation in individual attributes and social factors (such as helping effort, dominance status, and group structure) influence rates of aging in males and females; (2) how do these factors influence measured levels of oxidative stress, a suggested marker of physiological senescence; and (3) how does variation in social investment received during development influence adult survival and condition? We will address the last question using a large-scale field experiment in which we provision pups with nutrients for growth or with antioxidants to test for downstream effects on adult condition, reproductive performance, and levels of oxidative stress. The research will generate important new information on the main factors influencing variation and mortality and fertility in natural populations of social vertebrates, and how natural selection shapes the evolution of life history in long-lived animals living in close-knit family groups, including, potentially, ancestral humans. In addition, our work will provide the first test of mechanistic explanations of senescence in a natural mammal population, and the first experimental test of early-life effects on adult fitness traits. These investigations promise to advance our understanding of the evolutionary processes and proximate causes of aging.