Supernaturalizing Social Life: Religion and the Evolution of Human Cooperation. Human Nature 18:272–294

This paper examines three ancient traits of religion whose origins likely date back to the Upper Paleolithic: ancestor worship, shamanism, and the belief in natural and animal spirits. Evidence for the emergence of these traits coincides with evidence for a dramatic advance in human social cooperation. It is argued that these traits played a role in the evolution of human cooperation through the mechanism of social scrutiny. Social scrutiny is an effective means of reducing individualism and enhancing pro-social behavior. Religion’s most ancient traits represent an extension of the human social world into the supernatural, thus reinforcing within-group cooperation by means of ever-vigilant spiritual monitors. Believing that the spirits were always watching may have helped reduce the number of non-cooperators within a group while reinforcing group behavioral norms, thus allowing human-like levels of cooperation to emerge.