We have long attributed man's violent, aggressive, competitive nature to his animal ancestry. But what if we are just as given to cooperation, empathy, and morality by virtue of our genes? From a scientist and writer whom E. O. Wilson has called 'the world authority on primate social behavior' comes a lively look at the most provocative aspects of human nature - power, sex, violence, kindness, and morality - through our two closest cousins in the ape family. For nearly 20 years, Frans de Waal has worked with both the famously aggressive chimpanzee and the lesser-known egalitarian, erotic, matriarchal bonobo, two species whose DNA is nearly identical to that of humans. He brings these apes to life on every page, revealing their personalities, relationships, and power struggles, creating an engrossing narrative that explores what their behaviour can teach us about ourselves and each other.