This book examines why individuals and communities invest heavily in their religious life through multi-disciplinary perspectives. It pursues philosophical, psychological, deep time historical and adaptive answers to this question. Religion is a profoundly puzzling phenomenon from an evolutionary perspective. Commitment to religion is typically expensive, and most of the beliefs that motivate it cannot be true (since religious belief systems are inconsistent with one another). Yet some form of religion seems to be universal and resilient in historically known cultures – though not, if archaeology is to be trusted, in human communities early in the evolution of our species. We have collectively invented religion over about the last 100,000 years. Stemming from an interdisciplinary workshop, this book grapples with these challenges and features diverse contributions: some offer evolutionary and historical analyses, identifying hidden adaptive benefits to religion independent of the veracity of religious belief; others see connections between religious commitment and commitment to the social norms that make cooperative life possible, and explore aspects of human psychology that make religious belief tempting. Broad in scope and theoretically ambitious, Religion and Its Evolution: Signals, Norms and Secret Histories will be a key resource for scholars and researchers of religious studies, sciences of religion, psychology, anthropology, the cultural evolution of religion and the sociology of religion. This book was originally published as a special issue of Religion, Brain & Behavior.