The emergence of large-scale cooperation during the Holocene remains a central problem in the evolutionary literature. One hypothesis points to culturally evolved beliefs in punishing, interventionist gods that facilitate the extension of cooperative behaviour toward geographically distant co-religionists. Furthermore, another hypothesis points to such mechanisms being constrained to the religious ingroup, possibly at the expense of religious outgroups. To test these hypotheses, we administered two behavioural experiments and a set of interviews to a sample of 2228 participants from 15 diverse populations. These populations included foragers, pastoralists, horticulturalists, and wage labourers, practicing Buddhism, Christianity, and Hinduism, but also forms of animism and ancestor worship. Using the Random Allocation Game (RAG) and the Dictator Game (DG) in which individuals allocated money between themselves, local and geographically distant co-religionists, and religious outgroups, we found that higher ratings of gods as monitoring and punishing predicted decreased local favouritism (RAGs) and increased resource-sharing with distant co-religionists (DGs). The effects of punishing and monitoring gods on outgroup allocations revealed between-site variability, suggesting that in the absence of intergroup hostility, moralizing gods may be implicated in cooperative behaviour toward outgroups. These results provide support for the hypothesis that beliefs in monitoring and punitive gods help expand the circle of sustainable social interaction, and open questions about the treatment of religious outgroups.

Centre for Culture and Evolution Brunel University London Middlesex UB8 3PH UK

Department of Anthropology Ball State University Muncie IN 47306 USA

Department of Anthropology Montclair State University Montclair NJ 07043 USA

Department of Anthropology University of California Davis Davis CA 95616 USA

Department of Anthropology University of Connecticut Storrs CT 06269 USA

Department of Anthropology Washington University in St Louis St Louis MO 63130 USA

Department of Economics and Government Harvard University Cambridge MA 02138 USA

Department of Human Behavior Ecology and Culture Max Planck Institute for Evolutionary Anthropology Leipzig 04103 Germany

Department of Human Evolutionary Biology Harvard University Cambridge MA 02138 USA

Department of Human Evolutionary Biology Harvard University Cambridge MA 02138 USA 2 LEVYNA Laboratory for the Experimental Research of Religion Masaryk University Brno 602 00 Czech Republic

Department of Psychology University of Auckland Auckland New Zealand

Department of Psychology University of Auckland Auckland New Zealand 6 Department of Linguistic and Cultural Evolution Max Planck Institute for the Science of Human History Jena 07745 Germany

Department of Psychology University of British Columbia Vancouver BC Canada V6T 1Z4

Department of Psychology University of Pennsylvania Philadelphia PA 6241 USA

Institute of Human Origins Arizona State University Tempe AZ 4101 USA

LEVYNA Laboratory for the Experimental Research of Religion Masaryk University Brno 602 00 Czech Republic

School of Anthropology and Museum Ethnography University of Oxford Oxford OX2 6PE UK 9 Wadham College University of Oxford Oxford OX2 6PE UK

School of Psychology Victoria University of Wellington Wellington 6140 New Zealand

Social Science Sub Division College of DuPage Glen Ellyn IL 60137 USA

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