Introducing a special issue on phase two of the Evolution of Religion and Morality project

This special double issue, Religion, Brain & Behavior’s first ever double issue, presents results from the second phase of the Evolution of Religion and Morality (ERM) project. Results from the first phase of this pioneering and influential project were published in a previous special issue of RBB (2018, volume 8, issue 2) and elsewhere (e.g., Purzycki et al., 2016). The core of this second wave of research employs experimental games—the Dictator Game and Random Allocation Game—as well as demographic and economic data to explore the relationship between beliefs in particular types of supernatural agents and cooperative behavior. Similar to the previous RBB special issue on the ERM project, this issue presents independent articles on each of the field sites from the project. These articles allowed the ERM researchers to describe the cultural and historical context of their field studies, and offered an opportunity to conduct more rigorous intra-field site analyses in ways that were not possible in the synthetic cross-cultural study previously published with the second-wave data (Lang et al., 2019). Each of these studies explores ethnographically-derived questions that afford rich insights about the subsistence, ecological, and economic variation in the collective ERM data set. In addition to these experimental and interview studies, this issue also offers four new synthetic pieces. First, Baimel et al. analyze the relationship between religious commitments and material insecurity. They show that across the 15 ERM field sites, Christian sites exhibit the strongest relationship between religious commitment and belief in a moralizing god, and this relationship is positively predicted by material insecurity. Second, Vardy et al. use the collective ERM data set to explore the oft-cited gender gap in which women exhibit higher levels of religious commitment than men. Consistent with previous research, the ERM findings support a religious gender gap. However, this gap only arises for traditions with a moralizing god. Women do not exhibit greater religious commitments in traditions that worship local gods. Third, Purzycki et al. assess whether the supernatural agents that elicit commitments across the 15 field sites are interested in human morality. As anticipated, even when “official” or “theologically correct” claims deny that the gods maintain moral interest, across the ERM field sites study participants inferred that their gods, even local gods, were generally interested in their moral actions. In the final paper of this special issue, Purzcyki et al. wrap up the 10-year ERM project with a summary target article that examines the methodological and analytic challenges of a large multi-field site cross-disciplinary study. This article assesses the strengths and limitations of both phases of the ERM project, as well as offers advice for researchers aiming to pursue similarly ambitious projects. It provides a rare glimpse into the behind-the-scenes machinations of a long-term large-scale research endeavor. We elicited commentaries from five well-known scholars in the scientific study of religion—from anthropology, cognitive science, philosophy, and psychology— to comment on this article and the ERM project in general. The special issue concludes with a response to these commentaries from Purzycki et al. The impact of ERM on the biocultural study of religion in particular, and the academic study of religion in general, is only just beginning. In addition to the various scholarly debates that their results have initiated, ERM has strengthened a trend toward cross-cultural projects aimed at understanding variation in religious expression, commitment, and behavior. Indeed, the scientific study