Wars Beyond Groups

Abstract

For group-living animal species, it is normal for members of a group to cooperate to protect their home range or territory from bordering groups, threaten the members of other groups, and potentially attack them during intergroup encounters. When a neighboring group withdraws from the territorial border, in most cases, the other group feels content, ceases the attack, and reciprocally withdraws from the area without stepping into the neighbors’ territory. For the chimpanzee, however, skirmishes between adjacent groups often escalate into more serious situations. Male chimpanzees’ patrol behavior is notable. When chimpanzee males on patrol encounter a different group, the patrol transforms to become very physically aggressive. If they encounter a lone male from another group, they may surround him, lynch him, and kill him. If they encounter several males from another group together, a fierce battle will ensues [118].