PROXIMATE AND ULTIMATE INFLUENCES ON THE REGULATION OF MATING IN THE GREAT APES

Laboratory research on the great apes has revealed similarities in the proximate regulation of sexual behavior by hormonal, social, and spat ial variables but differences among the species in various sexual and reproductive characteristics. Laboratory research indicated that all t hree species of great ape exhibited heightened female sexual motivatio n during the midcycle, periovulatory phase of the menstrual cycle, con sistent with an interpretation of estrus. All three species were also similar in terms of mating at other times in the cycle as a result, pr imarily, of male sexual initiative/agression. Field research on the se xual behavior and social organization of the great apes under natural conditions suggested that the species differences were related, in par t, to the species' mating systems-that is, to differences in intermale competition and female choice at estrus. Consideration of both proxim ate and ultimate influences on behavioral regulation facilitates the s eparate objectives of research directed primarily toward one or the ot her type of influence. (C) 1995 Wiley-Liss, Inc.