Complex societies precede moralizing gods throughout world history.

The origins of religion and of complex societies represent evolutionary puzzles1-8. The 'moralizing gods' hypothesis offers a solution to both puzzles by proposing that belief in morally concerned supernatural agents culturally evolved to facilitate cooperation among strangers in large-scale societies9-13. Although previous research has suggested an association between the presence of moralizing gods and social complexity3,6,7,9-18, the relationship between the two is disputed9-13,19-24, and attempts to establish causality have been hampered by limitations in the availability of detailed global longitudinal data. To overcome these limitations, here we systematically coded records from 414 societies that span the past 10,000 years from 30 regions around the world, using 51 measures of social complexity and 4 measures of supernatural enforcement of morality. Our analyses not only confirm the association between moralizing gods and social complexity, but also reveal that moralizing gods follow-rather than precede-large increases in social complexity. Contrary to previous predictions9,12,16,18, powerful moralizing 'big gods' and prosocial supernatural punishment tend to appear only after the emergence of 'megasocieties' with populations of more than around one million people. Moralizing gods are not a prerequisite for the evolution of social complexity, but they may help to sustain and expand complex multi-ethnic empires after they have become established. By contrast, rituals that facilitate the standardization of religious traditions across large populations25,26 generally precede the appearance of moralizing gods. This suggests that ritual practices were more important than the particular content of religious belief to the initial rise of social complexity.

Tradition and invention: The bifocal stance theory of cultural evolution.

Cultural evolution depends on both innovation (the creation of new cultural variants by accident or design) and high-fidelity transmission (which preserves our accumulated knowledge and allows the storage of normative conventions). What is required is an overarching theory encompassing both dimensions, specifying the psychological motivations and mechanisms involved. The bifocal stance theory (BST) of cultural evolution proposes that the co-existence of innovative change and stable tradition results from our ability to adopt different motivational stances flexibly during social learning and transmission. We argue that the ways in which instrumental and ritual stances are adopted in cultural transmission influence the nature and degree of copying fidelity and thus also patterns of cultural spread and stability at a population level over time. BST creates a unifying framework for interpreting the findings of otherwise seemingly disparate areas of enquiry, including social learning, cumulative culture, overimitation, and ritual performance. We discuss the implications of BST for competing by-product accounts which assume that faithful copying is merely a side-effect of instrumental learning and action parsing. We also set out a novel "cultural action framework" bringing to light aspects of social learning that have been relatively neglected by behavioural ecologists and evolutionary psychologists and establishing a roadmap for future research on this topic. The BST framework sheds new light on the cognitive underpinnings of cumulative cultural change, selection, and spread within an encompassing evolutionary framework.

Bifocal stance theory: An effort to broaden, extend, and clarify.

The bifocal stance theory (BST) of cultural evolution has prompted a wide-ranging discussion with broadly three aims: to apply the theory to novel contexts; to extend the conceptual framework; to offer critical feedback on various aspects of the theory. We first discuss BST's relevance to the diverse range of topics which emerged from the commentaries, followed by a consideration of how our framework can be supplemented by and compared to other theories. Lastly, the criticisms that were raised by a subset of commentaries allow us to clarify parts of our theory.

Quantitative historical analysis uncovers a single dimension of complexity that structures global variation in human social organization.

Do human societies from around the world exhibit similarities in the way that they are structured, and show commonalities in the ways that they have evolved? These are long-standing questions that have proven difficult to answer. To test between competing hypotheses, we constructed a massive repository of historical and archaeological information known as "Seshat: Global History Databank." We systematically coded data on 414 societies from 30 regions around the world spanning the last 10,000 years. We were able to capture information on 51 variables reflecting nine characteristics of human societies, such as social scale, economy, features of governance, and information systems. Our analyses revealed that these different characteristics show strong relationships with each other and that a single principal component captures around three-quarters of the observed variation. Furthermore, we found that different characteristics of social complexity are highly predictable across different world regions. These results suggest that key aspects of social organization are functionally related and do indeed coevolve in predictable ways. Our findings highlight the power of the sciences and humanities working together to rigorously test hypotheses about general rules that may have shaped human history.

Rituals Improve Children's Ability to Delay Gratification.

To be accepted into social groups, individuals must internalize and reproduce appropriate group conventions, such as rituals. The copying of such rigid and socially stipulated behavioral sequences places heavy demands on executive function. Given previous research showing that challenging executive functioning improves it, it was hypothesized that engagement in ritualistic behaviors improves children's executive functioning, in turn improving their ability to delay gratification. A 3-month circle time games intervention with 210 schoolchildren (Mage  = 7.78 years, SD = 1.47) in two contrasting cultural environments (Slovakia and Vanuatu) was conducted. The intervention improved children's executive function and in turn their ability to delay gratification. Moreover, these effects were amplified when the intervention task was imbued with ritual, rather than instrumental, cues.

Four things we need to know about extreme self-sacrifice.

A comprehensive explanation of extreme self-sacrifice would ideally clarify not only the proximate mechanisms leading to this behaviour, but also its developmental origins, its functions (if any), and its history. The theoretical framework set out in my target article has something to say about all of these dimensions, and many of the criticisms raised in the commentaries can therefore be addressed under those four main headings. In my response, I also discuss a set of proposals for further extending the framework. Finally, I conclude by distilling from the discussion a host of novel questions requiring further investigation.

Dying for the group: Towards a general theory of extreme self-sacrifice.

Whether upheld as heroic or reviled as terrorism, people have been willing to lay down their lives for the sake of their groups throughout history. Why? Previous theories of extreme self-sacrifice have highlighted a range of seemingly disparate factors, such as collective identity, outgroup hostility, and kin psychology. In this paper, I attempt to integrate many of these factors into a single overarching theory based on several decades of collaborative research with a range of special populations, from tribes in Papua New Guinea to Libyan insurgents and from Muslim fundamentalists in Indonesia to Brazilian football hooligans. These studies suggest that extreme self-sacrifice is motivated by identity fusion, a visceral sense of oneness with the group, resulting from intense collective experiences (e.g., painful rituals or the horrors of frontline combat) or from perceptions of shared biology. In ancient foraging societies, fusion would have enabled warlike bands to stand united despite strong temptations to scatter and flee. The fusion mechanism has often been exploited in cultural rituals, not only by tribal societies but also in specialized cells embedded in armies, cults, and terrorist organizations. With the rise of social complexity and the spread of states and empires, fusion has also been extended to much larger groups, including doctrinal religions, ethnicities, and ideological movements. Explaining extreme self-sacrifice is not only a scientific priority but also a practical challenge as we seek a collective response to suicide, terrorism, and other extreme expressions of outgroup hostility that continue to bedevil humanity today.

Brothers in arms: Libyan revolutionaries bond like family.

What motivates ordinary civilians to sacrifice their lives for revolutionary causes? We surveyed 179 Libyan revolutionaries during the 2011 conflict in Libya. These civilians-turned-fighters rejected Gaddafi's jamahiriyya (state of the masses) and formed highly cohesive fighting units typical of intense conflicts. Fighters reported high levels of "identity fusion"--visceral, family-like bonds between fighters and their battalions. Fusion of revolutionaries with their local battalions and their own families were extremely high, especially relative to Libyans who favored the revolution but did not join battalions. Additionally, frontline combatants were as strongly bonded to their battalion as they were to their own families, but battalion members who provided logistical support were more fused with their families than battalions. Together, these findings help illuminate the social bonds that seem to motivate combatants to risk their lives for the group during wartime.

In-Group Ostracism Increases High-Fidelity Imitation in Early Childhood.

The Cyberball paradigm was used to examine the hypothesis that children use high-fidelity imitation as a reinclusion behavior in response to being ostracized by in-group members. Children (N = 176; 5- to 6-year-olds) were either included or excluded by in- or out-group members and then shown a video of an in-group or an out-group member enacting a social convention. Participants who were excluded by their in-group engaged in higher-fidelity imitation than those who were included by their in-group. Children who were included by an out-group and those who were excluded by an out-group showed no difference in imitative fidelity. Children ostracized by in-group members also displayed increased anxiety relative to children ostracized by out-group members. The data are consistent with the proposal that high-fidelity imitation functions as reinclusion behavior in the context of in-group ostracism.

Religion promotes a love for thy neighbour: But how big is the neighbourhood?

The term prosocial has often been taken to mean nice or neighbourly, but many acts that further in-group interests are hostile and aggressive towards out-groups. According to Norenzayan et al., religion's ability to foster social cohesion within religious groups has been a key factor in the human transition to complex societies. But what are the prospects for nonparochial "religious prosociality"?

Why care for humanity?

Some of the most pressing challenges facing our planet-such as climate change, biodiversity loss, warfare and extreme poverty-require social cohesion and prosocial action on a global scale. How can this be achieved? Previous research suggests that identity fusion-a strong form of group cohesion motivating prosocial action-results from perceptions of shared personally transformative experiences or of common biological essence. Here, we present results from two studies with United States samples exploring each pathway to identity fusion on a global scale. Study 1 focused on globally shared motherhood experiences and found that US mothers were more fused with women around the world if they shared motherhood experiences with them, which was also reflected in money allocation behaviour. Study 2 showed that exposure to a talk about globally shared biology increased fusion with humanity at large, Americans and the extended family suggesting that fusion with humanity does not need to weaken fusion with nation or extended family. We discuss implications of our results for future research on bonding with humanity at large and for addressing collective action problems on a global scale.

How shared suffering bonded Britons witnessing the Queen's funeral.

Previous research suggests that sharing emotionally intense experiences with others, for example by undergoing dysphoric collective rituals together, can lead to "identity fusion," a visceral feeling of oneness that predicts group cohesion and self-sacrifice for the group. In this pre-registered research, we provide the first quantitative investigation of identity fusion following participation in a national funeral, surveying 1632 members of the British public. As predicted, individuals reporting intense sadness during Queen Elizabeth II's funeral exhibited higher levels of identity fusion and pro-group commitment, as evidenced by generosity pledges to a British Monarchist charity. Also consistent with our hypotheses, feelings of unity in grief and emotional sharedness during the event mediated the relationship between sadness intensity and pro-group commitment. These findings shed light on importance of collective rituals in fostering group cohesion, cooperation, and the dynamics of shared emotional experiences within communities.

Disentangling the evolutionary drivers of social complexity: A comprehensive test of hypotheses.

During the Holocene, the scale and complexity of human societies increased markedly. Generations of scholars have proposed different theories explaining this expansion, which range from broadly functionalist explanations, focusing on the provision of public goods, to conflict theories, emphasizing the role of class struggle or warfare. To quantitatively test these theories, we develop a general dynamical model based on the theoretical framework of cultural macroevolution. Using this model and Seshat: Global History Databank, we test 17 potential predictor variables proxying mechanisms suggested by major theories of sociopolitical complexity (and >100,000 combinations of these predictors). The best-supported model indicates a strong causal role played by a combination of increasing agricultural productivity and invention/adoption of military technologies (most notably, iron weapons and cavalry in the first millennium BCE).

Wrath of God: religious primes and punishment.

Recent evidence indicates that priming participants with religious concepts promotes prosocial sharing behaviour. In the present study, we investigated whether religious priming also promotes the costly punishment of unfair behaviour. A total of 304 participants played a punishment game. Before the punishment stage began, participants were subliminally primed with religion primes, secular punishment primes or control primes. We found that religious primes strongly increased the costly punishment of unfair behaviours for a subset of our participants--those who had previously donated to a religious organization. We discuss two proximate mechanisms potentially underpinning this effect. The first is a 'supernatural watcher' mechanism, whereby religious participants punish unfair behaviours when primed because they sense that not doing so will enrage or disappoint an observing supernatural agent. The second is a 'behavioural priming' mechanism, whereby religious primes activate cultural norms pertaining to fairness and its enforcement and occasion behaviour consistent with those norms. We conclude that our results are consistent with dual inheritance proposals about religion and cooperation, whereby religions harness the byproducts of genetically inherited cognitive mechanisms in ways that enhance the survival prospects of their adherents.

The Development of Identity Fusion.

The fusion of personal and group identities can lead to self-sacrificial progroup behavior, from acts of charity to violent extremism. Two pathways to identity fusion-via shared biology and shared experiences-have been proposed. In this article, we elucidate a new developmental account of the origins and mechanisms of these two pathways to identity fusion from childhood to adulthood. Whereas fusion based on shared biology occurs from early childhood cued by phenotypic similarity, fusion based on episodic memories of shared experiences is not possible until midadolescence and relies on suitable bonding experiences (e.g., painful initiation rituals, emotionally intense team sports). The critical development that enables fusion based on shared experiences is autobiographical reasoning, which entails connecting one's past experiences to the present self. Autobiographical reasoning begins in adolescence, which may explain the flourishing of fusion in late adolescence and young adulthood relative to other life periods. Fusion via either pathway is linked to strong progroup behavior. We outline a program of empirical research on the development of identity fusion while addressing relevant methodological challenges. A developmental framework may help foster efforts to harness identity fusion for peaceful rather than violent forms of self-sacrifice for the group.

Preverbal infants expect agents exhibiting counterintuitive capacities to gain access to contested resources.

Claims to supernatural power have been used as a basis for authority in a wide range of societies, but little is known about developmental origins of the link between supernatural power and worldly authority. Here, we show that 12- to 16-month-old infants expect agents exhibiting counterintuitive capacities to win out in a two-way standoff over a contested resource. Infants watched two agents gain a reward using either physically intuitive or physically counterintuitive methods, the latter involving simple forms of levitation or teleportation. Infants looked longer, indicating surprise, when the physically intuitive agent subsequently outcompeted a physically counterintuitive agent in securing a reward. Control experiments indicated that infants' expectations were not simply motived by the efficiency of agents in pursuing their goals, but specifically the deployment of counterintuitive capacities. This suggests that the link between supernatural power and worldly authority has early origins in development.