Female Sexual Receptivity
Human females are potentially sexually receptive all of the time. In contrast, most great apes are only receptive during a short window during which the female is ovulating. During this time, female apes show external anogenital swellings indicating their receptivity. Bonobos are unique among the apes as in captivity they are receptive during upto 75% of their cycle and copulations can occur at almost any stage of their menstrual cycle and may reflect the use of sexual activity to relieve tension, prevent conflict and reconcile after a conflict.