Rita Anne McNamara

The cultural evolution of prosocial religions

We develop a cultural evolutionary theory of the origins of prosocial religions and apply it to resolve two puzzles in human psychology and cultural history: (1) the rise of large-scale cooperation among strangers and, simultaneously, (2) the spread of prosocial religions in the last 10-12 millennia. We argue that these two developments were importantly linked and mutually energizing. We explain how a package of culturally evolved religious beliefs and practices characterized by increasingly potent, moralizing, supernatural agents, credible displays of faith, and other psychologically active elements conducive to social solidarity promoted high fertility rates and large-scale cooperation with co-religionists, often contributing to success in intergroup competition and conflict. In turn, prosocial religious beliefs and practices spread and aggregated as these successful groups expanded, or were copied by less successful groups. This synthesis is grounded in the idea that although religious beliefs and practices originally arose as nonadaptive by-products of innate cognitive functions, particular cultural variants were then selected for their prosocial effects in a long-term, cultural evolutionary process. This framework (1) reconciles key aspects of the adaptationist and by-product approaches to the origins of religion, (2) explains a variety of empirical observations that have not received adequate attention, and (3) generates novel predictions. Converging lines of evidence drawn from diverse disciplines provide empirical support while at the same time encouraging new research directions and opening up new questions for exploration and debate.

Moralistic gods, supernatural punishment and the expansion of human sociality.

Since the origins of agriculture, the scale of human cooperation and societal complexity has dramatically expanded. This fact challenges standard evolutionary explanations of prosociality because well-studied mechanisms of cooperation based on genetic relatedness, reciprocity and partner choice falter as people increasingly engage in fleeting transactions with genetically unrelated strangers in large anonymous groups. To explain this rapid expansion of prosociality, researchers have proposed several mechanisms. Here we focus on one key hypothesis: cognitive representations of gods as increasingly knowledgeable and punitive, and who sanction violators of interpersonal social norms, foster and sustain the expansion of cooperation, trust and fairness towards co-religionist strangers. We tested this hypothesis using extensive ethnographic interviews and two behavioural games designed to measure impartial rule-following among people (n = 591, observations = 35,400) from eight diverse communities from around the world: (1) inland Tanna, Vanuatu; (2) coastal Tanna, Vanuatu; (3) Yasawa, Fiji; (4) Lovu, Fiji; (5) Pesqueiro, Brazil; (6) Pointe aux Piments, Mauritius; (7) the Tyva Republic (Siberia), Russia; and (8) Hadzaland, Tanzania. Participants reported adherence to a wide array of world religious traditions including Christianity, Hinduism and Buddhism, as well as notably diverse local traditions, including animism and ancestor worship. Holding a range of relevant variables constant, the higher participants rated their moralistic gods as punitive and knowledgeable about human thoughts and actions, the more coins they allocated to geographically distant co-religionist strangers relative to both themselves and local co-religionists. Our results support the hypothesis that beliefs in moralistic, punitive and knowing gods increase impartial behaviour towards distant co-religionists, and therefore can contribute to the expansion of prosociality.

Impartial Institutions, Pathogen Stress and the Expanding Social Network

Anthropologists have documented substantial cross-society variation in people’s willingness to treat strangers with impartial, universal norms versus favoring members of their local community. Researchers have proposed several adaptive accounts for these differences. One variant of the pathogen stress hypothesis predicts that people will be more likely to favor local in-group members when they are under greater infectious disease threat. The material security hypothesis instead proposes that institutions that permit people to meet their basic needs through impartial interactions with strangers reinforce a tendency toward impartiality, whereas people lacking such institutions must rely on local community members to meet their basic needs. Some studies have examined these hypotheses using self-reported preferences, but not with behavioral measures. We conducted behavioral experiments in eight diverse societies that measure individuals’ willingness to favor in-group members by ignoring an impartial rule. Consistent with the material security hypothesis, members of societies enjoying better-quality government services and food security show a stronger preference for following an impartial rule over investing in their local in-group. Our data show no support for the pathogen stress hypothesis as applied to favoring in-groups and instead suggest that favoring in-group members more closely reflects a general adaptive fit with social institutions that have arisen in each society.

Supernatural punishment, in-group biases, and material insecurity: experiments and ethnography from Yasawa, Fiji

Threat of supernatural punishment can promote prosociality in large-scale societies; however, its impact in smaller societies with less powerful deities is less understood. Also, while perceived material insecurity has been associated with increasing religious belief, the relationships between insecurity, supernatural punishment beliefs, and prosocial behavior are unclear. In this study, we explore how material insecurity moderates the supernatural punishment beliefs that promote different expectations about distant, anonymous strangers among a sample of villagers living in Yasawa, Fiji. We examined this relationship by employing an economic game designed to measure local recipient favoritism vs. egalitarian, rule-following behavior. Using indices of three different “punishing” agents – the Christian God (“Bible God”), the deified ancestors (Kalou-vu), and the police – we find that increased belief in Bible God punishment predicts less local recipient favoritism at low and moderate but not high material insecurity. Punishing Kalou-vu also predicts less favoritism at low and moderate insecurity, but more favoritism at high insecurity. Police punishment poorly predicts favoritism, suggesting that secular authority has less impact on isolated communities. We discuss implications for understanding how different kinds of supernatural and secular agent beliefs impact prosocial behavior.

The evolution of religion and morality : A synthesis of ethnographic and experimental evidence from eight societies

ABSTRACT Understanding the expansion of human sociality and cooperation beyond kith and kin remains an important evolutionary puzzle. There is likely a complex web of processes including institutions, norms, and practices that contributes to this phenomenon. Considerable evidence suggests that one such process involves certain components of religious systems that may have fostered the expansion of human cooperation in a variety of ways, including both certain forms of rituals and commitment to particular types of gods. Using an experimental economic game, our team specifically tested whether or not individually held mental models of moralistic, punishing, and knowledgeable gods curb biases in favor of the self and the local community, and increase impartiality toward geographically distant anonymous co-religionists. Our sample includes 591 participants from eight diverse societies – iTaukei (indigenous) Fijians who practice both Christianity and ancestor worship, the animist Hadza of Tanzania, Hindu Indo-Fijians, Hindu Mauritians, shamanist-Buddhist Tyvans of southern Siberia, traditional Inland and Christian Coastal Vanuatuans from Tanna, and Christian Brazilians from Pesqueiro. In this article, we present cross-cultural evidence that addresses this question and discuss the implications and limitations of our project. This volume also offers detailed, site-specific reports to provide further contextualization at the local level.

Cross-cultural dataset for the evolution of religion and morality project

A considerable body of research cross-culturally examines the evolution of religious traditions, beliefs and behaviors. The bulk of this research, however, draws from coded qualitative ethnographies rather than from standardized methods specifically designed to measure religious beliefs and behaviors. Psychological data sets that examine religious thought and behavior in controlled conditions tend to be disproportionately sampled from student populations. Some cross-national databases employ standardized methods at the individual level, but are primarily focused on fully market integrated, state-level societies. The Evolution of Religion and Morality Project sought to generate a data set that systematically probed individual level measures sampling across a wider range of human populations. The set includes data from behavioral economic experiments and detailed surveys of demographics, religious beliefs and practices, material security, and intergroup perceptions. This paper describes the methods and variables, briefly introduces the sites and sampling techniques, notes inconsistencies across sites, and provides some basic reporting for the data set.

Material security, life history, and moralistic religions: A cross-cultural examination

Researchers have recently proposed that “moralistic” religions—those with moral doctrines, moralistic supernatural punishment, and lower emphasis on ritual—emerged as an effect of greater wealth and material security. One interpretation appeals to life history theory, predicting that individuals with “slow life history” strategies will be more attracted to moralistic traditions as a means to judge those with “fast life history” strategies. As we had reservations about the validity of this application of life history theory, we tested these predictions with a data set consisting of 592 individuals from eight diverse societies. Our sample includes individuals from a wide range of traditions, including world religions such as Buddhism, Hinduism and Christianity, but also local traditions rooted in beliefs in animism, ancestor worship, and worship of spirits associated with nature. We first test for the presence of associations between material security, years of formal education, and reproductive success. Consistent with popular life history predictions, we find evidence that material security and education are associated with reduced reproduction. Building on this, we then test whether or not these demographic factors predict the moral concern, punitiveness, attributed knowledge-breadth, and frequency of ritual devotions towards two deities in each society. Here, we find no reliable evidence of a relationship between number of children, material security, or formal education and the individual-level religious beliefs and behaviors. We conclude with a discussion of why life-history theory is an inadequate interpretation for the emergence of factors typifying the moralistic traditions.

Jesus vs. the ancestors: how specific religious beliefs shape prosociality on Yasawa Island, Fiji

ABSTRACT We investigate how religious beliefs in an omnipotent, omniscient God vs. locally concerned, more limited gods impact prosocial behavior at varying degrees of social distance. We recruit participants from traditional villages on Yasawa Island, Fiji. Yasawan religion includes belief in both universalistic Christian teachings and local deified ancestor spirits (Kalou-vu). Yasawans’ contrasting reliance on local, kin-based social networks and anonymous economic market exchange provides an interesting test case for how religious beliefs interact with wider social structures. We use an experimental priming procedure to test whether reminders of Christian vs. traditional imagery, as compared to neutral, influence local or self-favoritism in the random allocation game (RAG). We find that traditional imagery caused increased local – but not self – favoritism. Priming effects depended upon perceived resource uncertainty: participants primed with Christian imagery were most likely to allocate to distant co-religionists when they were least worried about resources. However, more uncertainty predicted higher local RAG allocations, further suggesting the importance of local social networks for managing such uncertainty. We further find additional support for previous findings that prosocial effects of punitive supernatural agent beliefs depend upon uncertainty. These findings further emphasize the interplay between contents of cultural forms like religious belief and socioecological context.

Re-contextualizing the re-explanation: understanding religion requires accounting for both ecological and social dynamics

In describing the challenges facing evolutionary theorizing about the early origins of religion, Sterelny identifies modern cross-cultural religious variation as a reason to conclude that religion may not have a singular origin. While this conclusion may be appealing on its face, the complexities of population dynamics are better handled by mathematical modeling to account for non-linear processes that produce evolutionary changes over time. Models that examine effects of social learning in cultural change suggest that learning biases can still produce clusters of like-minded individuals nested within an array of groups that broadly disagree with each other, much like existing variation seen in religion today (Axelrod, 1997; Friedkin, Proskurnikov, Tempo, & Parsegov, 2016; Kempe, Kleinberg, Oren, & Slivkins, 2016). Importantly, these results illustrate how social learners having access to a limited range of the total population of teachers produces limited dispersal of cultural knowledge, which in turn produces cultural groups that can be acted upon by natural selection at both the individual and cultural group levels. However, in order for the group structuring effects of such limited dispersal social transmission to matter, the model would need to take a second factor into account: the relative intensity of withinvs. between-group competition. Kin selection and group selection can follow the same evolutionary dynamics and act upon populations depending on the scale of competition (West, Griffin, & Gardner, 2007). For example, Pseudomonas aeruginosa bacteria will evolve to be more cooperative in the local group of genetic relatives when competition is higher globally across groups than locally within groups (Griffin, West, & Buckling, 2004; Queller, 2004). Similar processes of parochial altruism also likely influenced early human social evolution (Bernhard, Fischbacher, & Fehr, 2006; Choi & Bowles, 2007). Extrapolating from these kin selection/group selection results, one might hypothesize that more local competition should disfavor grouping, while more global competition should favor cooperative local groups that compete with other groups. Sterelny emphasizes the adaptive benefits of ritual as a means of solidifying group bonds. This implies that humans are more inclined to disperse and act as autonomous units than to group. Accordingly, the social cohesion provided by rituals becomes the impetus for humans to get the benefits of group cooperation. However, group cooperation can evolve and individuals can gain larger selfish, direct fitness benefits from cooperation than defection if payoffs to the individual from the group outweigh the costs of their contribution (West et al., 2007). For example, suppose that there are three experts in crafting and using obsidian spearheads. One day, instead of going hunting, one donates their time to teach three novice hunters how to make and use spearheads. Now there are six hunters, doubling the group’s capacity to catch meat. Given the group structuring effects of limited dispersal social transmission mentioned above, early human populations may have been forming groups purely for the individual benefits of gaining information from each other. Importantly, individual direct benefit from group cooperation can arise even when groups are non-cohesive. Returning to the hunter example, suppose there is a neighboring group across a ravine. Hunters on the other side of the ravine use a less efficient spearhead technique. The groups are not competing, so the teacher allows a novice from the neighboring group into lessons. This novice takes the teachings to their group, and now both groups use the more efficient technique. Therefore, if betweengroup competition is low, then more fluid group boundaries allow further dispersal of socially acquired information and reduce across-group cultural variation. However, if the groups were

Do minds switch bodies? Dualist interpretations across ages and societies

ABSTRACT Researchers explain cultural phenomena ranging from cognitive biases to widespread religious beliefs by assuming intuitive dualism: humans imagine minds and bodies as distinct and separable. We examine dualist intuition development across two societies that differ in normative focus on thinking about minds. We use a new method that measures people’s tendency to interpret ambiguous stimuli using mind-body dualist thinking. We recruited 180 Canadian children (2–10 yrs) along with 42 Indigenous iTaukei Fijian children (5–13 yrs) and 38 Indigenous iTaukei Fijian adults (27–79 yrs) from a remote island community. Participants tracked a named character within ambiguous animations that could be interpreted as a mind-body switch. Animations vary “agency cues” that participants might rely on for dualistic interpretations. Results indicate early emerging dualistic inclinations across populations and reliance on “agency cues” of body proximity and appearance of eyes. “Agency cues” increase dualist interpretations from 10% to 70%, though eyes mattered more for Westernized participants. Overall, statistical models positing that dualist interpretations “emerge early and everywhere” fit our data better than models positing that dualism “develops gradually with exposure to Western cultural traditions.” Fijian participants, who normatively avoid focus on minds, offered even more dualistic interpretations when they had less Western cultural exposure (via formal education).