Chimpanzee friends fight together to battle rivals

(Max Planck Institute for Evolutionary Anthropology) Humans cooperate with each other in large groups to defend territories or wage war. But what underlies the evolution of this kind of cooperation? Researchers at the Max PIanck Institute for Evolutionary Anthropology and Harvard University show that there may be a link between social bonds and participation in large-scale cooperation: Chimpanzees join their close bond partners when fighting rivals. In humans, too, social bonds may have been ess...