Social Explanations for Chimpanzee Hunting

Chimpanzees hunt vertebrates more often and eat more meat than do any other nonhuman primates, and meat from captured prey is typically distributed among multiple individuals. Also, they and bonobos are our closest living relatives.  For these reasons, they have received much attention in discussions of the ecological and social importance of hunting and meat eating in human evolution.  The fundamental importance of hunting and meat eating to chimpanzees lies in the fact that meat has high nutritional value.  This value introduces possibilities that, as has been documented or proposed for humans and some earlier hominins, chimpanzees increase their nutritional gains by hunting cooperatively and that males share meat tactically to develop and maintain social bonds with each other and/or to increase their mating success.  However, evidence adduced in support of each of these possibilities has been the subject of controversy.  I will briefly review the controversies and summarize new data from research at Ngogo, in Uganda, relevant to the social bonding hypothesis.  Resolving the debate about cooperation depends partly on how we define that term; it also depends on identifying a proper ecological “currency” and on experimental investigation of chimpanzee cognitive abilities.  No compelling evidence in support of the “mating success” hypothesis exists.  However, Ngogo data provide some support for the “social bonding’ hypothesis.  They also highlight the fact that, as with many other aspects of chimpanzee behavior, variation exists within and among chimpanzee populations in the social importance of hunting and meat eating.