The evolution of female sexuality

Females in monogamous species tend to be more sexually active than females in species with other mating systems. In this paper we consider the possibi lity that female sexuality has evolved because more sexually active females have received more male assistance. We develop a model in which there is n o direct cue available to males indicating whether the female is fertile. I nstead males might respond to female behaviour as an indirect cue. The latt er could favour increased female sexuality if males tend to stay longer wit h more sexually active females. Our results show that female sexual behavio ur can have a significant impact on social behaviour and that sexually acti ve females and sexual behaviour outside fertile periods can evolve under so me circumstances. We end with a discussion of theories of the evolution of female sexuality. We believe that theories based on male assistance fit emp irical findings better than theories based on variation in male genetic qua lity. (C) 2001 The Association for the Study of Animal Behaviour.