Cooperative behavior has been one of the enigmas of evolutionary theory since the days of Charles Darwin. The contributions to this book examine the many facets of cooperative behavior in primates and humans as some of the world's leading experts review and summarize the state of the art of theoretical and empirical studies of cooperation. This book is thus the first to bridge the gap between parallel research in primatology and studies of humans. Comparative as this approach is, it highlights both common principles and aspects of human uniqueness with respect to cooperative behavior.