Effects of Oxytocin on Chimpanzee Social Attention

抄録

The role of oxytocin has gained significant attention for its role in regulating social behaviour. An evolutionarily ancient neuropeptide, it was originally described primarily for its role in affiliative and prosocial behaviours, but recent studies in humans are beginning to demonstrate that it also plays an important part in outgroup aggression. New perspectives following these studies emphasize oxytocin's role in promoting "groupmindedness," increasing individuals' tendency to cooperate and support one's own group, while at the same time increasing antagonism towards and bias against those perceived as outgroup. Despite numerous studies in humans, monkeys, and dogs, there are very few studies on the effects of oxytocin in non-human great ape species. Here, we non-invasively administered intranasal oxytocin to 6 chimpanzees using a nebulized mist which the chimpanzees breathed while drinking juice. As a preliminary experiment, following administration of either oxytocin or saline placebo, chimpanzees were shown images of both ingroup and outgroup faces while their gaze was recorded with an eye tracker. We compared time looking at the eyes, often associated with empathy and prosociality, between ingroup and outgroup faces. To our knowledge this is the first study to combine oxytocin administration and eye-tracking in a non-human great ape species. A trend was found suggesting differences in social attention as a result of oxytocin administration, and further analyses will be conducted to reveal the precise effects of oxytocin on chimpanzee social gaze.