Accepted codes of conduct and established religions are features of human societies throughout the world. Why should this be? In this book, biologist Donald Broom argues that these aspects of human culture have evolved as a consequence of natural selection; that morally acceptable behaviour benefits the humans and other animals and that a principal function of religion is to underpin and encourage such behaviour. The author provides biological insights drawn especially from work on animal behaviour and presents ideas and information from the fields of philosophy and theology to produce a thought-provoking, interdisciplinary treatment. Scientists who read this book will gain an appreciation of the wider literature on morality and religion, and non-scientists will benefit from the author’s extensive knowledge of the biological mechanisms underlying the behaviour of humans and other social animals.