Oxytocin promotes social grooming in bonobos

Abstract

AbstractOxytocin has attracted research attention due to its role in promoting social bonding. One notable recent hypothesis is the biobehavioral feedback loop, which posits that the oxytocin system has evolved to support the formation and maintenance of social bonds through a positive feedback loop, where oxytocin promotes social behaviours which then cause oxytocin release themselves. In the two Pan species, humans’ closest relatives, oxytocin is known to be released following key behaviours related to social bonding, such as social grooming in chimpanzees and female-female sexual behaviour in bonobos. However, no experimental evidence has demonstrated that oxytocin promotes such socio-positive behaviours. To test this, we administered nebulized oxytocin or saline placebo to a group of female bonobos and subsequently observed the change in their gross behavior during free interaction. We found that bonobos groomed other group members significantly more frequently in the oxytocin compared to placebo condition. Other behavioural measures did not largely differ between conditions, except for a nonsignificant trend for reduction in abnormal regurgitation/reingestion behaviour. Overall, we found that oxytocin promoted socio-positive interaction in bonobos, providing support for the biobehavioural feedback loop hypothesis of oxytocin in bonobo social evolution.