LAUSR

Significance In striking contrast to chimpanzees, tolerant between-group interactions in bonobos, our other closest living relative, have been suggested as a pathway to understanding the evolution of human between-group peacemaking and cooperation. However, due to the lack of data on bonobo group dynamics and partitioning, bonobo between-group tolerance has been routinely challenged. Here, we compared the social systems of bonobos and chimpanzees to find distinct and stable social groups in bonobos that interact regularly and peacefully. Despite their tolerant meetings that exceed the rates previously described between human groups, bonobo groups maintained exclusive social and spatial borders. Tolerance occurring between socially distinct groups highlights the potential of bonobos as a referential model for the evolution of between-group cooperation in humans.