Why religion and spirituality are important in human biological research.

The study of human biology includes exploration of all the genetic and environmental influences on human variation and life history, including impacts of sociocultural and physical environments. Religious practice and spirituality may be one of these influences. There are more than 5.8 billion religiously affiliated adults and children, accounting for 84% of the world's 6.9 billion people. Furthermore, 70% of Americans consider themselves spiritual in some way, including 22% who do not consider themselves religious, and the numbers for Europe are lower but proportionally similar. Such a high rate of religious affiliation and spiritual belief suggests that religion and spirituality could be sociocultural influences on human variation, but human biologists have scarcely attended to their impacts, as indicated by the limited numbers of relevant articles in the two flagship human biology journals. In this article, we discuss why human biologists may have overlooked this important force for human variability and highlight foundational work from human biology and other disciplines that can give our colleagues directions forward. We review the impacts of religion and spirituality at population and individual levels and call for human biologists to attend to the many aspects of religion and spirituality that can impact human biology and are much more than simply influences of denominational affiliation.