Why is there so much conflict in the Balkans, the Middle East, Africa, and many other parts of the world? Is there something innate in human nature that makes it next to impossible to achieve peaceful coexistence? The answer, says career diplomat Carl Coon, must be sought in the distant prehistoric past when intergroup hostility became ingrained as a pattern of cultural evolution. For thousands of generations, our ancestors organised themselves in distinctive groups that competed with one another. Sometimes the competition was peaceful, but more often than not the struggle took violent...

In this succinct, highly readable overview of the evolution of human society, the author argues that the 21st century will witness a crucially important and difficult transition for the human race. Blending the disciplines of anthropology and evolutionary psychology with over thirty years of experience in the diplomatic corps, Coon traces the evolution of the human tendency to divide others into two groups, "us versus them." People tend instinctively to behave altruistically toward members of their own in-group, and to react with suspicion, or even hostility, toward outsiders. He points out...