Spanning many different epochs and varieties of religious experience, this book develops a new approach to religion and its role in human history. The authors look across a range of religious phenomena-from ancestor worship to totemism, shamanism, and worldwide modern religions-to offer a new explanation of the evolutionary success of religious behaviors. Their book is more empirical and verifiable than most previous books on evolution and religion because they develop an approach that removes guesswork about beliefs in the supernatural, focusing instead on the behaviors of individuals. The result is a pioneering look at how and why natural selection has favored religious behaviors throughout history.

A fundamentally new approach to religion that differs from all other explanations by defining religion not in terms of unidentifiable beliefs in the supernatural, but by the identifiable behavior of communicating acceptance of supernatural claims. This approach distinguishes different forms of religious behavior, from the ancestor worship, totemism, and shamanism of traditional societies, to the behavior of prophets that started the world religions, by their different supernatural claims. Communicating acceptance of any supernatural claim tends to promote cooperative social relationships because it communicates a willingness to accept unskeptically the influence of the speaker in a way similar to a child's acceptance of the influence of a parent. This is why the clearest identifiable effect of religious behavior is the promotion of cooperative family-like social relationships: parent/child-like relationships between the individuals making and accepting the supernatural claims and sibling-like relationships among coacceptors of those claims. As religious behaviors, and the increased cooperation they produce, are copied from one generation to the next, the number of cooperating codescendants has tended to increase. Thus, religion can be seen as a descendant-leaving strategy of our ancestors that has been favored by natural selection and has become a human universal found in all known cultures.