Societies develop as a result of the interactions of individuals as they compete and cooperate with one another in the evolutionary struggle to survive and reproduce successfully. Gorilla society is arranged according to these different and sometimes conflicting evolutionary goals of the sexes. In seeking to understand why gorilla society exists as it does, Alexander H. Harcourt and Kelly J. Stewart bring together extensive data on wild gorillas, collected over decades by numerous researchers working in diverse habitats across Africa, to illustrate how the social system of gorillas has...