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
Sex determination in Silene and mutations in the Y chromosome during reproduction, then different sex-linked genes are lost. The different combinations of possible sex-related genes that an individual "Silene" can have in one Y chromosome are what creates the rich variation of sexual phenotypes throughout this genus. The system for determining sex in "Silene latifolia" is close to that found in humans because in both cases the Y chromosome determines what reproductive mechanisms will be expressed in the offspring. They differ because there are multiple sex determining genes on the Y chromosome of "S. latifolia", while in humans the presence or absence of the