social bonding in rats. Oxytocin and primate sexual behaviour Oxytocin plays a similar role in non-human primates as it does in humans. Grooming, sex, and cuddling frequencies correlate positively with levels of oxytocin. As the level of oxytocin increases so does sexual motivation. While oxytocin plays a major role in parent child relationships, it is also found to play a role in adult sexual relationships. Its secretion affects the nature of the relationship or if there will even be a relationship at all. Studies have shown that oxytocin is higher in monkeys in lifelong monogamous relationships compared to monkeys which are single. Furthermore, the oxytocin levels of the couples correlate positively; when the oxytocin secretion of one increases, the other one also increases. Higher levels of oxytocin are related to monkeys expressing more behaviours such as cuddling, grooming and sex, while lower levels of oxytocin reduce motivation for these activities. Research on oxytocin's role in the animal brain suggests that it plays less of a role in behaviours of love and affection than previously believed. "When oxytocin was first discovered in 1909, it was thought mostly to influence a mother's labour contractions and milk let-down. Then, in the 1990s, research with prairie voles found that giving them a dose of oxytocin resulted in the formation of a bond with their future mate (Azar, 40)." Oxytocin has since been treated by the media as the sole player in the "love and mating game" in mammals. This view, however, is proving to be false as, "most hormones don't influence behaviour directly. Rather, they affect thinking and emotions in variable ways (Azar, 40)." There is much more involved in sexual behaviour in the mammalian animal than oxytocin and vasopressin can explain. Pleasure It is often assumed that animals do not have sex for pleasure, or alternatively that humans, pigs, bonobos (and perhaps dolphins and one or two more species of primates) are the only species that do. This is sometimes stated as "animals mate only for reproduction". This view is considered a misconception by some scholars. Jonathan Balcombe argues that the prevalence of non-reproductive sexual behaviour in certain species suggests that sexual stimulation is pleasurable. He also points to the presence of the clitoris in some female mammals, and evidence for female orgasm in primates. On the other hand, it is impossible to know the subjective feelings of animals, and the notion that