Chimpanzee males compete for position in a dominance hierarchy; status often depends on support from other members, including females, of the group. High-ranking males have much greater sexual access to females in estrus. Males control females by physical violence and intimidation. Chimpanzees also engage in purposeful raids to kill members of other chimpanzee groups. This inter-group violence can help explain intra-group violence. To fend off attack from other groups, males must remain in groups and that requires males to compete for mating opportunities within the community. Competition for the scarce resource, eggs, leads to male-male violence and male coercion of females. If the alpha male monopolized all reproductive potential, then evolution would push non-dominant males to either fight continually for dominance or to leave the group and find females elsewhere. The chimpanzee solution is to allow all males some, though very unequal, reproductive possibility.

Reading assignment:

Peterson, Dale and Richard Wrangham. Demonic Males: Apes and the Origins of Human Violence, chapters 10 and 11

De Waal, Frans. "Bonobo Sex and Society." Scientific American (March 1995), pp. 82-88

De Waal, Frans. Chimpanzee Politics: Power and Sex among Apes, chapters 2 and 4

De Waal, Frans. Our Inner Ape, pp. 75-79

Resources: Notes - Lecture 2 [PDF]