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
Moral status of animals in the ancient world attempt the creation of a taxonomical categorization and hierarchy of animals. Aristotle perceived some similarities between humans and other species and developed a sort of "psychological continuum", recognising that human and non-human animals differ only by degree in possessing certain temperaments. Nevertheless, he denied animals rationality and moral equality. "Plants are created for the sake of animals," he wrote, "and animals for the sake of men." Aristotle argued that humans were the “masters” in his created hierarchical structure based upon their rational powers. One of Aristotle's pupils, Theophrastus, argued against eating meat on the grounds that it robbed animals of