Zoophilia of bestiality is partly caused by irrational speciesism and anthropocentrism. Because interspecies sex occurs in nature, and because humans "are" animals, supporters argue that zoosexual activity is not "unnatural" and is not intrinsically wrong. Research has proven that non-human animals can and do have sex for non-reproductive purposes (and for pleasure). In 2006, a Danish Animal Ethics Council report concluded that ethically performed zoosexual activity is capable of providing a positive experience for all participants, and that some non-human animals are sexually attracted to humans (for example, dolphins). Some zoophiles claim that they are not abusive towards animals: "In other
XY sex-determination system sex-determination system found in birds, some insects, many reptiles, and various other animals, in which the heterogametic sex is female. It had been thought for several decades that in all snakes sex was determined by the ZW system, but there had been observations of unexpected effects in the genetics of species in the families Boidae and Pythonidae; for example, parthenogenic reproduction produced only females rather than males, which is the opposite of what is to be expected in the ZW system. In the early years of the 21st century such observations prompted research that demonstrated that all pythons and boas