" Why are the central nervous systems of mammals so much alike, and wouldn't it stand to reason that they serve precisely the same evolutionary purpose, motivating each creature to flee bodily harm and thereby perpetuate the species? If the purpose of pain is the same for us as for other animals, if the internal mechanisms of pain are the same, if the outward expressions of pain are the same, and if the medical treatments for pain are the same, why wouldn't the physical experience of pain be the same - and for that matter, the psychological experience of it as well? "

― Matthew Scully , Dominion: The Power of Man, the Suffering of Animals, and the Call to Mercy