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 be a code of ethics in the animal kingdom? Must an animal be human to be humane? In this book, a scientist takes on those who have declared ethics uniquely human. Making a case for a morality grounded in biology, he shows that ethical behaviour, in humans and animals alike, is as much a matter of evolution as any other trait. World famous for his descriptions of Machiavellian power plays among chimpanzees - the nastier side of animal life - Frans de Waal here contends that animals have a nice side as well. Making his case through anecdotes drawn from his work with apes and monkeys bolstered by the data from continuing research by himself and others, de Waal shows us that many of the building blocks of morality are natural: they can be observed in other animals. Through his eyes, we see how not just primates but all kinds of animals, from marine mammals to dogs, respond to social rules, helping one another, sharing food, resolving conflict to mutual satisfaction, even developing a crude sense of justice and fairness. Natural selection may be harsh, but it has produced highly successful species that survive through cooperation and mutual assistance. De Waal identifies this paradox as the key to an evolutionary account of morality, and demonstrates that human morality could never have developed without the foundation of fellow feeling our species share with other animals. As his work makes clear, a morality grounded in biology leads to an entirely different conception of what it means to be human - and humane.