The Evolution of Religion: How Cognitive By-Products, Adaptive Learning Heuristics, Ritual Displays, and Group Competition Generate Deep Commitments to Prosocial Religions Scott Atran Abstract CNRS Understanding religion requires explaining why supernatu- Institut Jean Nicod ral beliefs, devotions, and rituals are both universal and vari- Paris, France able across cultures, and why religion is so often associated & with both large-scale cooperation and enduring group conflict. John Jay College of Criminal Justice Emerging lines of research suggest that these oppositions result New York, NY, USA from the convergence of three processes. First, the interaction & of certain reliably developing cognitive processes, such as our ISR and Ford School of Public Policy University of Michigan ability to infer the presence of intentional agents, favors—as Ann Arbor, MI, USA an evolutionary by-product—the spread of certain kinds of [email protected] counterintuitive concepts. Second, participation in rituals and devotions involving costly displays exploits various aspects Joseph Henrich of our evolved psychology to deepen people’s commitment Department of Economics and Department of Psychology to both supernatural agents and religious communities. Third, University of British Columbia competition among societies and organizations with different Vancouver, BC, Canada faith-based beliefs and practices has increasingly connected re- [email protected] ligion with both within-group prosociality and between-group enmity. This connection has strengthened dramatically in re- cent millennia, as part of the evolution of complex societies, and is important to understanding cooperation and conflict in today’s world. Keywords by-product hypothesis, credibility enhancing displays, cultural transmission, cooperation, group competition, high gods, min- imally counterintuitive, morality, religion, rise of civilization March 8, 2010; revised and accepted March 29, 2010 18 Biological Theory 5(1) 2010, 18–30. c 2010 Konrad Lorenz Institute for Evolution and Cognition Research Scott Atran and Joseph Henrich [An] advancement in the standard of morality and an increase in population size, or in large-group interactions such as those the number of well-endowed men . who, from possessing in a high associated with many kinds of public goods or common dilem- degree the spirit of patriotism, fidelity, obedience, courage, and sym- mas (Boyd and Richerson 1988; Panchanathan and Boyd 2003; pathy, were always ready to give aid to each other and to sacrifice Nowak and Sigmund 2005; Mathew and Boyd 2009). Even themselves for the common good, would be victorious over other more telling is that none of these mechanisms explains the tribes. variation in cooperation among human societies, or the mas- — Charles Darwin, The Descent of Man sive expansion of cooperation in some societies over the last ten millennia (Henrich et al. 2005; Atran 2010). This synthesis integrates insights from studies of the cogni- Converging lines of field and experimental evidence sug- tive foundations of religion with evolutionary approaches to gest that cultural evolution, building on certain innate cognitive human cooperation to derive a deeper understanding of the foundations, has favored the emergence of beliefs in power- origin and development of prosocial religions. We argue that ful moralizing deities concerned with the prosocial behav- the cultural evolution of prosocial religions and the historical ior of individuals beyond kin- and reciprocity-based networks rise of large-scale civilizations involve the dynamic interaction (Norenzayan and Shariff 2008). Cross-cultural analysis of 186 of the by-products of adaptive cognitive mechanisms (e.g., societies has found that larger and more complex societies minimally counterintuitive beliefs and overextended agent were much more likely to subscribe to potent deities directly concepts), adaptive learning heuristics (e.g., emulation of concerned with morality and willing to punish norm violators successful and prestigious individuals), credibility-enhancing (Roes and Raymond 2003; Johnson 2005). Studies conducted ritual displays (e.g., self-sacrifice and costly commitments to across a diverse range of societies including foragers, farm- seemingly preposterous beliefs), and cultural group selection ers, and herders, show that professing a world religion pre- for those packages of rituals, devotions, and beliefs that best dicts greater fairness toward ephemeral interactants (Henrich sustain in-group prosocial norms (e.g., monumental undertak- et al. 2010). Experiments with North Americans show that ings, sacred values). unconsciously activating religious concepts lead to reduced Many religions pose an evolutionary enigma because they cheating and greater generosity toward strangers (Bargh and require costly commitments to beliefs that violate both core Chartrand 1999; Mazar and Ariely 2006; Shariff and Noren- aspects of logical consistency and our intuitive expectations zayan 2007), except among ardent atheists. Together, these about how the world works, both of which are otherwise crucial cross-cultural, historical, and experimental findings suggest for successfully navigating the world (Atran and Norenzayan that (1) religion—as a phenomenon with potentially deep 2004). Religious practices are often costly in terms of material roots (Klein 1989)—has not always been about high mor- sacrifice (ranging from human sacrifice to prayer time), emo- alizing gods and (2) modern world religions may have evolved tional expenditure (inciting fears and hopes), and cognitive to create a potent linkage between the supernatural and the effort (maintaining conflicting models about the nature of the prosocial. Thus, we hypothesize that cultural evolutionary pro- world). One anthropological review of religious offerings con- cesses, driven by competition among groups, have exploited cludes: “Sacrifice is giving something up at a cost. ‘Afford aspects of our evolved psychology, including certain cognitive it or not,’ the attitude seems to be” (Firth 1963). by-products, to gradually assemble packages of supernatural At the same time, the origin of large-scale cooperative beliefs, devotions, and rituals that were increasingly effective human societies is also an evolutionary puzzle because people at instilling deep commitment, galvanizing internal solidarity, frequently cooperate and trade with non-relatives in ephemeral and sustaining larger-scale cooperation. interactions (Fehr and Fischbacher 2003). Thus, while the evo- lutionary mechanisms associated with kinship, reciprocity, and Ordinary Cognition Produces Extraordinary Agents reputation clearly influence cooperation in important ways, they do not capture the fullest extent of human prosocial- Humans are purpose-seeking, cause-inferring, story-telling an- ity. Kinship cannot explain cooperation among non-relatives imals (Gazzaniga et al. 2009). As Hume noted in The Natural (Henrich and Henrich 2007), though “fictive kinship”—a cul- History of Religion, the greater the impact of events on our tural manipulation of kin psychology—may contribute to mo- lives, the greater is our drive to impose purpose and coherence bilizing larger groups (Johnson 1987; Atran 2003). Reciprocity on those events. This view is backed by a recent experiment does not suffice to explain cooperation beyond dense so- in which people were asked what patterns they could see in cial networks, small villages, or tightly knit neighborhoods arrangements of dots or stock market figures (Whitson and (Hruschka and Henrich 2006; Allen-Arave et al. 2008; Atran Galinsky 2008). Before asking, the experimenters made half 2010). Neither direct nor indirect reciprocity can explain coop- the participants feel a lack of control. Those who experienced eration in transient interactions in large populations, because a lack of control were more likely to see patterns and processes reputational information rapidly degrades as a function of underlying the randomness, suggesting that under uncertainty Biological Theory 5(1) 2010 19 The Evolution of Religion we are more likely to find preternatural explanations for the at least until supernatural agents were harnessed by cultural randomness. Both cross-cultural experiments and surveys in- evolution to begin demanding costly actions and cooperation, dicate that people more readily ascribe to the veracity of nar- under threat of divine punishment or offers of sublime rewards. ratives containing counterintuitive elements (e.g., miracles) How do our minds make agent concepts into gods? Cogni- when primed with death (Norenzayan and Hansen 2006), or tive approaches propose that supernatural concepts exploit or- when facing danger or insecurity, as with pleas of hope for dinary mental processes to construct counterintuitive concepts God’s intervention during wartime (Argyle and Beit-Hallahmi (Boyer 2001; Atran 2002; Barrett 2004). Religious beliefs are 2000). Such findings help explain both cross-national analyses counterintuitive because they violate universal expectations showing that a country’s religiosity (devotion to a world reli- about the world’s mundane structure. This includes the ba- gion) is positively related to its degree of existential insecurity sic categories of our “intuitive ontology” (i.e., the ontology (Norris and Inglehart 2004), and why certain kinds of religions of our semantic system), such as person, animal, plant, and enjoy revivals in challenging times. The issue then becomes: substance (Whythe 1993; Sperber