Ethical life began – probably between 100,000 and 50,000 years ago – when our ancestors started to look for ways of addressing the tensions that arose within their societies. Thanks to psychological adaptations that had evolved long before, in the lineage leading to our most recent common ancestor with the chimpanzees and bonobos, those distant predecessors were able to develop an unusual form of social life. They could live in bands of thirty to seventy individuals, mixed by age and sex. Doing so rested on a capacity for identifying the needs, desires, plans, and intentions of those with whom they were in daily contact, and on an ability to adjust their own behavior in pursuit of common goals. They were responsive to one another, and thus able to cooperate. Yet their responsiveness was limited, and, in consequence, so was the cooperation. Often the pressures of perceived self-interest overwhelmed their other-directed tendencies. Partners yesterday would be at cross purposes today. Quarrels broke out, and peace had to be refashioned through time-consuming acts of mutual reassurance. Although they could engage in their unusual form of social life, they could not do so smoothly or well.