Why be nice? Cooperation among wild chimpanzees

Humans cooperate more often, in more contexts, and with more partners than any other vertebrate. While anthropologists, behavioral ecologists and psychologists have made considerable headway comparing the cooperative capacities of humans and other taxa, a greater understanding of why wild primates cooperate leads to a clearer picture of the selective pressures that early humans faced. I study the adaptive value of cooperation in the contexts of hunting, territory defense, coalitionary aggression and social bonds among wild chimpanzees in Gombe National Park, Tanzania and Kibale National Park, Uganda. My analysis of more than 70 years of behavioral, spatial, genetic and hormonal data from these sites, coupled with my own field observations highlight the importance of simple, ecological explanations for cooperation that hinge on immediate, selfish benefits. I argue that while chimpanzees exhibit a wide range of cooperative abilities, cognitively complex mechanisms involving delayed, social benefits explain only a small proportion of the cooperation observed in the wild. Therefore, the degree of dependence upon such mechanisms in humans evolved after our lineage split from the great apes.