Book excerpt: Why is revenge such a pervasive and destructive problem? How can we create a future in which revenge is less common and forgiveness is more common? Psychologist Michael McCullough argues that the key to a more forgiving, less vengeful world is to understand the evolutionary forces that gave rise to these intimately human instincts and the social forces that activate them in human minds today. Drawing on exciting breakthroughs from the social and biological sciences, McCullough dispenses surprising and practical advice for making the world a more forgiving place. Michael E. McCullough (Miami, Florida), an internationally recognized expert on forgiveness and revenge, is a professor of psychology at the University of Miami in Coral Gables, Florida, where he directs the Laboratory for Social and Clinical Psychology.