Sex and context: Hormones and primate sexual motivation

Gonadal hormones regulate the ability to copulate in most mammalian species , but not in primates because copulatory ability has been emancipated from hormonal control. Instead, gonadal hormones primarily influence sexual moti vation. This separation of mating ability from hormonally modulated mating interest allows social experience and context to powerfully influence the e xpression of sexual behavior in nonhuman primates, both developmentally and in adulthood. For example, male rhesus monkeys mount males and females equ ally as juveniles, but mount females almost exclusively as adults. Having e jaculated with a female better predicted this transition to female mounting partners than did increased pubertal testosterone (T). It is proposed that increased pubertal T stimulates male sexual motivation, increasing the mal e's probability of sexual experience with females, ultimately producing a s exual preference for females. Eliminating T in adulthood reduces male sexua l motivation in both humans and rhesus monkeys, but does not eliminate the capacity to engage in sex. In male rhesus monkeys the effects of reduced an drogens on sexual behavior vary with social status and sexual experience. H uman sexual behavior also varies with hormonal state, social context, and c ultural conventions. Ovarian hormones influence female sexual desire, but t he specific sexual behaviors engaged in are affected by perceived pregnancy risk, suggesting that cognition plays an important role in human sexual be havior. How the physical capacity to mate became emancipated from hormonal regulation in primates is not understood. This emancipation, however, incre ases the importance of motivational systems and results in primate sexual b ehavior being strongly influenced by social context. (C) 2001 Academic Pres s.