Animal sexual behaviour 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. It is often assumed that animals do not have sex for pleasure, or alternatively that humans, pigs, bonoboes (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
Non-reproductive sexual behavior in animals have provided good evidence that animals have instinct and a reward system. The behavior of laboratory animals demonstrates a mental experience wherein the animal's instincts tell it if it carries out a certain action, it will then receive what it needs. For example, the lab rat will push the lever because it knows food will fall out of the hole in the wall. It does not need awareness, but it does seem to work on a reward system. The lab rat learned the action needed to be fed. Studies of the brain have proven that pleasure and displeasure are an