Morality is often defined in opposition to the natural "instincts," or as a tool to keep those instincts in check. New findings in neuroscience, social psychology, animal behavior, and anthropology have brought us back to the original Darwinian position that moral behavior is continuous with the social behavior of animals, and most likely evolved to enhance the cooperativeness of society. In this view, morality is part of human nature rather than its opposite. This interdisciplinary volume debates the origin and working of human morality within the context of science as well as religion and philosophy. Experts from widely different backgrounds speculate how morality may have evolved, how it develops in the child, and what science can tell us about its working and origin. They also discuss how to deal with the age-old facts-versus-values debate, also known as the naturalistic fallacy. The implications of this exchange are enormous, as they may transform cherished views on if and why we are the only moral species.