Chimp Sex: Surprisingly Complicated

British psychologist Simon Townsend certainly picked an interesting line of work. Instead of getting bogged down in human neuroses, he chose to spend 10 months camping in the Budongo Forest of Uganda, monitoring the active sex lives of a group of chimpanzees and making audio recordings of their sexual encounters. Besides providing fodder for interesting cocktail party conversations, Townsend also made some interesting discoveries about when and why female chimps cry out during mating. He found that they stay silent when mating with a low-status male, but let out loud "copulation calls" when mating with a high-status fellow. However, they're also likely to stay silent if there's a high-status female nearby who might break up the tryst. The findings, published in the journal Public Library of Science ONE, come as something of a surprise. Previously, researchers thought that female chimps used the calls to advertise their availability and attract more mates.