Less offspring due to territorial conflicts

Both humans and chimpanzees can be extremely territorial, and territorial disputes between groups can turn violent, with individuals killing each other. In humans, such between-group competition can escalate to war and devastating loss of human life. Researchers from the Max Planck Institute for Evolutionary Anthropology studied wild Western chimpanzees to find out whether territorial behavior may have shaped counter-strategies. One important strategy that is evident in both humans and chimpanzees, but rare in the rest of the animal kingdom, is the capacity to work together in order to achieve a goal, for example to defend a territory—even if it is together with individuals who are not one's kin.