Wade, a longtime journalist covering genetic advances for The New York Times, draws widely on the work of scientists who have made crucial breakthroughs in establishing the reality of recent human evolution. The most provocative claims in this book involve the genetic basis of human social habits. What we might call middle class social traits-thrift, docility, nonviolence, have been slowly but surely inculcated genetically within agrarian societies, Wade argues. While these values have a strong cultural component, Wade argues that evolution has played its part.