Stacy Rosenbaum: UCLA Department of Anthropology, Center for Behavior, Evolution and Culture

Social relationships between adult male mountain gorillas and the infants in their groups are quite remarkable, characterized by extreme tolerance, grooming, playing, and many hours of male “babysitting.” This is true even in the 40% of groups that contain multiple adult males, where paternity certainty is low. My previous work demonstrated that 1) low-cost parenting is the most likely function of these relationships, and 2) preferences for individual male social partners persist across considerable time spans, even after social upheaval. This talk will examine the beginnings of such relationships, specifically the role maternal facilitation plays. Mothers increase their time near adult males in the first year after infants are born, and there is some evidence that they narrow their male social circle, spending more time near one preferred male than they do when infants get older. For a subsample of the population, male rank is a much better predictor of females’ choice of male social partner than either paternity or mating history. I will discuss the implications these findings have for understanding paternal kin discrimination and the evolution of intra-species variability in social structure.