Intergroup violence and parochial altruism are both prominent traits in human society. However, differences in behaviour towards in-group members and extra-group individuals are also widely documented in other group-living animals. Renowned for their peaceful nature and amicable temperament, bonobos (Pan paniscus) are highly tolerant even in intergroup contexts. Similar to humans, social interactions between groups can vary from aggressive to friendly in bonobos; but unlike their sister Pan species the chimpanzees, intergroup conflicts rarely escalate into lethal attacks in bonobos. To date, models of Hominid social evolution are heavily centred on chimpanzee sociality, where interactions with extra-group are mostly hostile. Little is known about the potential benefits and selection pressure of maintaining harmonious intergroup relationships, which is also a hallmark feature in human society. In order to explore the proximate and ultimate mechanisms underlying both intergroup violence and large-scale cooperation, I collected behavioural and non-invasive endocrinological data from two neighbouring communities of wild bonobos at the Kokolopori Bonobo Reserve in the Democratic Republic of Congo from October 2016 to August 2018. By examining the behavioural interactions of males and females within- and between-groups during intergroup encounters, as well as comparing within-group interactions during and outside encounters, I will test three hypotheses: mating opportunity hypothesis, feeding competition hypothesis and oxytocin hypothesis. Ultimately, findings from this project will help us better understand the evolutionary forces driving the evolution of warfare and prosociality in humans.

Leveda is a PhD student from the Max-Planck Institute for Evolutionary Anthropology. Her main research interest is primate social behaviour and its evolution. Her PhD study is on the behavioural and physiological correlates of intergroup encounters in wild bonobos. Previously, Leveda worked as a field assistant in the tropical rainforest of North Sulawesi, Indonesia, for 10 months, collecting data on the social behaviour and monitoring the stress levels and health of crested macaques (Macaca nigra). Prior to that, she was involved in a project to habituate a new community of chimpanzees (Pan troglodytes) in the Budongo Forest Reserve, Uganda. For her Master’s project, Leveda studied the effect of social relationships on functionally referential call production in chimpanzees at Edinburgh Zoo, Scotland.