Wallen Kim, Zehr Julia L
Emory University, Department of Psychology, 532 Kilgo Circle, Atlanta, GA 30322, USA.
J Sex Res. 2004 Feb;41(1):101-12. doi: 10.1080/00224490409552218.
Sexual behavior is required for reproduction in internally fertilizing species but poses significant social and physical risks. Females in many nonprimate species have evolved physical and behavioral mechanisms restricting sexual behavior to when females are fertile. The same hormones producing female fertility also control these mechanisms, assuring that sex only occurs when reproduction is possible. In contrast to nonprimate mammals, hormones do not regulate the capacity to engage in sex in female anthropoid primates, uncoupling fertility and the physical capacity to mate. Instead, in primates, sexual motivation has become the primary coordinator between sexual behavior and fertility. This dependence upon psychological mechanisms to coordinate physiology with behavior is possibly unique to primates, including humans, and allows a variety of nonphysiological influences, particularly social context, to regulate sexual behavior. The independence between hormonal state and sexual behavior allows sex to be used for social purposes. This complex regulation of primate sexuality develops during adolescence, where female monkeys show both hormonally influenced sexual motivation and socially modulated sexual behavior. We present findings from rhesus monkeys illustrating how social context and hormonal state interact to modulate adolescent and adult sexuality. It is argued that this flexibility in sexual behavior, combined with a tight regulation of sexual motivational systems by reproductive hormones, allows sexual behavior to be used for nonreproductive purposes while still assuring its occurrence during periods of female fertility. The evolutionary pressures that produced such flexibility in sexual behavior remain puzzling, but may reflect the importance of sexuality to primate social attraction and cohesion.
对于体内受精的物种而言，性行为是繁殖所必需的，但却带来了重大的社会和生理风险。许多非灵长类物种的雌性已经进化出了生理和行为机制，将性行为限制在雌性处于排卵期的时候。产生雌性生育能力的相同激素也控制着这些机制，确保只有在有可能繁殖时才会发生性行为。与非灵长类哺乳动物不同，激素并不调节雌性类人猿灵长类动物进行性行为的能力，生育能力与交配的身体能力不再相关联。相反，在灵长类动物中，性动机已成为性行为和生育能力之间的主要协调因素。这种依赖心理机制来协调生理与行为的情况可能是灵长类动物（包括人类）所独有的，并且允许各种非生理影响因素，特别是社会环境，来调节性行为。激素状态与性行为之间的独立性使得性行为可被用于社会目的。灵长类动物性活动的这种复杂调节在青春期发展形成，在此期间，雌性猴子既表现出受激素影响的性动机，也表现出受社会调节的性行为。我们展示了恒河猴的研究结果，阐明了社会环境和激素状态如何相互作用以调节青少年和成年期的性活动。有人认为，性行为的这种灵活性，再加上生殖激素对性动机系统的严格调节，使得性行为能够被用于非生殖目的，同时仍确保其在雌性排卵期发生。产生这种性行为灵活性的进化压力仍然令人费解，但可能反映了性对灵长类动物社会吸引力和凝聚力的重要性。
