Behaviour 2019
Age-Based Changes in Social Behaviour in Rhesus Macaques: Evidence for Social Selectivity
Erin R. Siracusa1, James P. Higham2, Noah Snyder-Mackler3, Lauren J.N. Brent1. 1University of Exeter, Exeter, Devon, United Kingdom; 2New York University, New York, New York, United States; 3Arizona State University, Tempe, Arizona, United States

Narrowing of social networks with age is commonly observed in human and non-human primates. Given the importance of social relationships for health and fitness in group-living species, shrinkage in networks with age has typically been thought to be maladaptive. However, recent research has suggested that older individuals might selectively prune their networks by focusing on important relationships. We tested this “social selectivity” hypothesis using 8-years of data from a population of female rhesus macaques on Cayo Santiago. Preliminary analyses reveal that while female macaques actively reduce their number of partners in old age, they spend similar amounts of time grooming and in proximity, suggesting that network narrowing does not result from lack of motivation or ability to socially engage. Additionally, aging females focus in on important partners such as kin. All age-related changes were the result of within-individual changes in behavior rather than differences among cohorts. Our findings add to a growing body of evidence showing that age-based changes in numbers of social partners may relate to adaptive changes in social selectivity among older individuals.