To observe a dog's guilty look. to witness a gorilla's self-sacrifice for a wounded mate, to watch an elephant herd's communal effort on behalf of a stranded calf--to catch animals in certain acts is to wonder what moves them. Might there he a code of ethics in the animal kingdom? Must an animal be human to he humane? In this provocative book, a renowned scientist takes on those who have declared ethics uniquely human. Making a compelling case for a morality grounded in biology, he shows how ethical behavior is as much a matter of evolution as any other trait, in humans and animals alike.