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
Emotion in animals during complex social interactions. However, Hof and Van Der Gucht clarify that they do not know the nature of such feelings in these animals and that we cannot just apply what we see in great apes or ourselves to whales. They believe that more work is needed to know whether emotions are the same for humans and whales. From at least the time of Darwin, it has been known that chimpanzees and other great apes also perform a laugh-like vocalization. Research with rats has revealed that under particular conditions, they emit 50-kHz ultrasonic vocalisations (USV) which have been postulated to