This article considers patterns of sexual behavior in the various nonhuman primates, and their possible relevance to understanding the origins of human sexuality. Copulatory patterns and frequencies vary, depending upon effects of sexual selection as well as natural selection, in various types of primate mating systems. Many monkeys and apes also employ sexual behavior in the wider context of social communication, and exhibit same-sex mounting in a variety of socio-sexual and bisexual contexts. Rhythmic changes in sexual behavior during menstrual cycles in the Old World monkeys and apes are discussed in relation to the human menstrual cycle and behavior.

Keywords:
copulatory patterns; menstrual cycle; sexual selection; sperm competition; socio-sexual behavior