Cannibalism is so repugnant to us that for years even anthropologists failed to admit that it was common in prehistory. It is easy to think: could other human beings really be capable of such a depraved act? But of course animal rights activists have a similarly low opinion of meat eaters, who not only cause millions of preventable deaths but do so with utter callousness: castrating and branding cattle without an anesthetic, impaling fish by the mouth and letting them suffocate in the hold of a boat, boiling lobsters alive. My point is not to make a moral case for vegetarianism but to shed light on the mindset of human violence and cruelty. History and ethnography suggest that people can treat strangers the way we now treat lobsters, and our incomprehension of such deeds may be compared with animal rights activists’ incomprehension of ours. It is no coincidence that Peter Singer, the author of The Expanding Circle, is also the author of Animal Liberation.

Steven Pinker, The Blank Slate: The Modern Denial of Human Nature, New York, 2002, p. 320