Anthropologists have often observed that various religious doctrines, taboos, practices, and rituals are linked to — and can be explained by — environmental factors or ecological imperatives. Cultural materialists, such as Marvin Harris and Michael Harner, in particular have unraveled puzzling or seemingly paradoxical religious practices (such as India’s sacred cow, the Jewish/Islamic taboo on pork, and Aztec sacrifice) by reference to the environment. Victor Reynolds and Ralph Tanner have covered similar topics in their biologically oriented book, The Social Ecology of Religion. While ecological approaches to religion rarely attempt to account for origins, such treatments offer keen insights into the ways in which religions are constructed and maintained. They are, therefore, relevant to any complete account of religion’s development over time and will be addressed in this Category.