People kill nonhuman animals for food, for their skins, and sometimes just for fun. We enslave animals and force them to work for us. We experiment on them and justify their suffering in terms of our advantage. Because most of us want to be able to view ourselves as good people (and, perhaps more importantly, because we want others to view us as good people), we may be motivated to view nonhumans in such a way that these activities are rendered morally unproblematic. One way to do this is to view other animals as utterly different from us.

(p. 111) - Darwin, God and the Meaning of Life: How Evolutionary Theory Undermines Everything You Think You Know (2010)