From the Harvard Gazette:
"Humans display a capacity for tolerance and cooperation among social groups that is rare in the animal kingdom, our long history of war and political strife notwithstanding. But how did we get that way?
Scientists believe bonobos might serve as an evolutionary model. The endangered primates share 99 percent of their DNA with humans and have a reputation for generally being peace-loving and sexually active — researchers jokingly refer to them “hippie apes.” And interactions between their social groups are thought to be much less hostile than among their more violent cousins, the chimpanzees.
Some, however, have challenged this because of a lack of detailed data on how these groups work and how they separate themselves. A new study led by Harvard primatologists Liran Samuni and Martin Surbeck on the social structure of bonobos may begin to fill in some of the blanks."