ABSTRACT
The greatest of the great apes could easily have grown extinct in the course of the twentieth century, and their disappearance would hardly have ranked as a cause for general dismay. All species of apes give birth to equal numbers of males and females. This equilibrium might lead us to imagine that monogamy is natural and universal, that nature tends to provide a male for every female, a female for every male. The males of the various species of apes are specialized in battling one another, thus assuring the physical strength and viability of each new generation, since it always descends from the winners. The females of the primates usually remain in heat for only a brief period of time; and these few days are the only period in which they are sexually available. While in heat, they mate with one male after another, and at the end of their period of heat they are highly likely to be pregnant.
