PhD Candidate at Princeton University
Co-Investigator: Jacinta Beehner
Approved: December 2011
Original Proposal Abstract:
Although strong male-male bonds are common in male-philopatric primates, evidence for male bonds in species where males disperse is rare. Despite potential reproductive consequences, little is known about how male-male bonds develop in these species. Geladas (Theropithecus gelada) provide an ideal model for investigating the ontogeny of male bonds in a female-bonded species. First, geladas live in a multi-level society comprising dozens of reproductive units, thus providing an unusually large sample size of study subjects. Second, juvenile males split their time between their natal unit and peer groups, and adolescent males split their time between peer groups and bachelor groups, offering several different social settings for establishing male relationships. Finally, a recent study on bachelor geladas suggests male-male relationships have reproductive consequences, and that these relationships are formed before males enter bachelor groups - highlighting the juvenile period as particularly important for study. In the proposed research, I will examine the nature of male-male relationships and identify the behavioral and hormonal factors that set juvenile gelada males on individual reproductive trajectories as they transition from their natal one-male unit, to a temporary peer group, and onwards to an all-male bachelor group. I will employ a combination of cross-sectional and longitudinal behavioral analyses, social network analysis and non-invasive fecal hormone sampling on all juvenile males (N=50) in a band of geladas in the Simien Mountains National Park, Ethiopia. This research will inform an understanding of early hominin behavior, especially behaviors related to male-male social bonding and tolerance, which are thought to have been important in early hominin evolution. It will also provide insight into the effects of early social conditions on development in hominins and other primates.