Humans have been considered unique for their ability to form relationships for mutual benefit not just within immediate kin groups but across and between them, even with total strangers.
It turns out that one of our closest living relatives, bonobos, are also able to think outside the group.
These were the findings of a Harvard study that involved two years of data collection in the deep forests of the Democratic Republic of Congo, where up to 20,000 of the endangered apes make their only home. The ability to engage in such “out-group” cooperation is the foundation on which humans have created societies and cultures through trade and knowledge-sharing.
“Our work with bonobos is showing that cooperation beyond social borders, without immediate payoff between unrelated individuals, is not uniquely human,” said senior author Martin Surbeck, assistant professor in the Department of Human Evolutionary Biology, who has researched bonobos for 20 years. The study was published in Science with lead author Liran Samuni, a former Harvard research associate who works at the German Primate Center in Göttingen.
A previous study, based on the same bonobo communities, found that the primates maintained distinct, stable social borders, so called “communities.” In their latest analysis, Samuni and Surbeck found evidence of cooperation between members of different communities, facilitated by an assortment of key individuals. These certain few consistently engaged in behaviors such as grooming and food-sharing and acted as links between groups — think ape ambassadors. Within each behavior, individuals cooperated with specific counterparts who were also good cooperators in that domain.