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 differences in humans verbal fluency and male advantage in physical power fade after age 25 in an asymmetric manner. She pointed out to several other studies on humans and other primates showing a levelling of sex differences in sociability and physical strength. Males and females might indeed have different timings of maturation of physical and verbal systems: according to McGuinness and Pribram (1978) during the first two years of life talking and walking rarely occur simultaneously, which suggests that these two abilities compete for the same set of neural connections, or that one type of neural organization inhibits the other. This coincides with