National Geographic has an excellent article by David Quammen about the science of bonobo behavior: "The Left Bank Ape: An Exclusive Look at Bonobo Behavior". Much has been made of the contrast between chimpanzee and bonobo behavior, often centered around the question of which of these two closest human relatives might be the better model for hominin origins. In reality, the Anthro 101 version of bonobo behavior radically oversimplifies their behavioral variation. As Quammen discusses, bonobo behavior in the wild holds some surprises for students enamored of the simplistic sex primate story.
That afternoon Hohmann and I sat beneath one of the thatch roofs discussing bonobo behavior. Few other researchers have seen bonobos in the act of predation, and those few reports generally involve small prey such as anomalures (only at Wamba) or baby duikers. Animal protein, insofar as bonobos get any, had seemed to come mainly from insects and millipedes. But Fruth and Hohmann reported nine cases of hunting by bonobos at Lomako, seven of which involved sizable duikers, usually grabbed by one bonobo, ripped apart at the belly while still alive, with the entrails eaten first, and the meat shared. More recently, here at Lui Kotale, they have seen another 21 successful predations, among which eight of the victims were mature duikers, one was a bush baby, and three were monkeys. Bonobos preying on other primates: “This is a regular part of the bonobo diet,” Hohmann said.
Sexiness, on the other hand, seemed to him less manifest than others, such as de Waal, had claimed. “I could show Frans some of the behaviors that he would not think are possible in bonobos,” Hohmann said. Infrequent sex, for instance. Yes, there’s a great diversity of sexual acts in the bonobo repertoire, but “a captive setting really amplifies all these behaviors. Bonobo behavior in the wild is different—must be different—because bonobos are very busy making their living, searching for food.”
Understanding the behavioral flexibility of both bonobos and chimpanzees is hugely important to the science of human origins. Meanwhile the continuing habitat loss and bushmeat trade threaten these creatures survival. Bonobo numbers remain fewer than 20,000 today. Their present genetic diversity is more comparable to the pattern of human variation than are chimpanzees, gorillas or orangutans. In that respect, at least, they may be the best primate model for our recent evolution. Hopefully genomics will begin to yield insights about the basis of bonobo-chimpanzee behavioral variation, which might open new doors to understand the evolution of the human brain.