bA powerful new theory of human nature suggests that our secret to success as a species is our unique friendlinessb pbBrilliant, eye-opening, and absolutely inspiring--and a riveting read. Hare and Woods have written the perfect book for our time.--Cass R. Sunstein, author of iHow Change Happensi and co-author of iNudgeib p For most of the approximately 300,000 years that iHomo sapiensi have existed, we have shared the planet with at least four other types of humans. All of these were smart, strong, and inventive. But around 50,000 years ago, iHomo sapiensi made a cognitive leap that gave us an edge over other species. What happened p Since Charles Darwin wrote about evolutionary fitness, the idea of fitness has been confused with physical strength, tactical brilliance, and aggression. In fact, what made us evolutionarily fit was a remarkable kind of friendliness, a virtuosic ability to coordinate and communicate with others that allowed us to achieve all the cultural and technical mar