Sarah F. Brosnan, Catherine F. Talbot, Jennifer L. Essler, Kelly Leverett, Timothy Flemming, Patrick Dougall, Carla Heyler and Paul J. Zak
Recent evidence indicates that oxytocin plays an important role in promoting prosocial behaviour amongst humans and other species. We tested whether oxytocin affected cooperation and food-sharing in capuchin monkeys, a highly cooperative New World primate. Subjects received either 2IU oxytocin or an inert adjuvent intranasally prior to each session. Oxytocin influenced food sharing in capuchins in ways we did not anticipate. Recipients were less likely to passively acquire food from possessors when either individual had received OT than in the control, and also spent less time in proximity to their partner. Passive food sharing requires proximity, and oxytocin decreased the capuchins’ typical congregating behaviour, apparently resulting in decreased sharing. We propose that the likely mechanism for increased social distance is the known anxiolytic effect of oxytocin. Our results indicate a need to consider how oxytocin affects the context of interactions and interacts with modes of sociality unique to each species.