Many of the most important properties of human groups – including properties that may give one group an evolutionary advantage over another – are properly defined only at the level of group organization. Yet at present, most work on the evolution of culture has focused solely on the transmission of individual-level traits. I propose a conceptual extension of the theory of cultural evolution, particularly related to the evolutionary competition between cultural groups. The key concept in this extension is the emergent (...) group-level trait. This type of trait is characterized by the structured organization of differentiated individuals and constitutes a unit of selection that is qualitatively different from selection on groups as defined by traditional multilevel selection theory. As a corollary, I argue that the traditional focus on cooperation as the defining feature of human societies has missed an essential feature of cooperative groups. Traditional models of cooperation assume that interacting with one cooperator is equivalent to interacting with any other. However, human groups involve differential roles, meaning that receiving aid from one individual is often preferred to receiving aid from another. In this target article, I discuss the emergence and evolution of group-level traits and the implications for the theory of cultural evolution, including ramifications for the evolution of human cooperation, technology, and cultural institutions, and for the equivalency of multilevel selection and inclusive fitness approaches. (shrink)

Recent debates about memetics have revealed some widespread misunderstandings about Darwinian approaches to cultural evolution. Drawing from these debates, this paper disputes five common claims: (1) mental representations are rarely discrete, and therefore models that assume discrete, gene-like particles (i.e., replicators) are useless; (2) replicators are necessary for cumulative, adaptive evolution; (3) content-dependent psychological biases are the only important processes that affect the spread of cultural representations; (4) the “cultural fitness” of a mental representation can be inferred from its successful (...) transmission; and (5) selective forces only matter if the sources of variation are random. We close by sketching the outlines of a unified evolutionary science of culture. (shrink)

Human cooperation is highly unusual. We live in large groups composed mostly of non-relatives. Evolutionists have proposed a number of explanations for this pattern, including cultural group selection and extensions of more general processes such as reciprocity, kin selection, and multi-level selection acting on genes. Evolutionary processes are consilient; they affect several different empirical domains, such as patterns of behavior and the proximal drivers of that behavior. In this target article, we sketch the evidence from five domains that bear on (...) the explanatory adequacy of cultural group selection and competing hypotheses to explain human cooperation. Does cultural transmission constitute an inheritance system that can evolve in a Darwinian fashion? Are the norms that underpin institutions among the cultural traits so transmitted? Do we observe sufficient variation at the level of groups of considerable size for group selection to be a plausible process? Do human groups compete, and do success and failure in competition depend upon cultural variation? Do we observe adaptations for cooperation in humans that most plausibly arose by cultural group selection? If the answer to one of these questions is “no,” then we must look to other hypotheses. We present evidence, including quantitative evidence, that the answer to all of the questions is “yes” and argue that we must take the cultural group selection hypothesis seriously. If culturally transmitted systems of rules that limit individual deviance organize cooperation in human societies, then it is not clear that any extant alternative to cultural group selection can be a complete explanation. (shrink)

Long before the origins of agriculture human ancestors had expanded across the globe into an immense variety of environments, from Australian deserts to Siberian tundra. Survival in these environments did not principally depend on genetic adaptations, but instead on evolved learning strategies that permitted the assembly of locally adaptive behavioral repertoires. To develop hypotheses about these learning strategies, we have modeled the evolution of learning strategies to assess what conditions and constraints favor which kinds of strategies. To build on prior (...) work, we focus on clarifying how spatial variability, temporal variability, and the number of cultural traits influence the evolution of four types of strategies: (1) individual learning, (2) unbiased social learning, (3) payoff-biased social learning, and (4) conformist transmission. Using a combination of analytic and simulation methods, we show that spatial—but not temporal—variation strongly favors the emergence of conformist transmission. This effect intensifies when migration rates are relatively high and individual learning is costly. We also show that increasing the number of cultural traits above two favors the evolution of conformist transmission, which suggests that the assumption of only two traits in many models has been conservative. We close by discussing how (1) spatial variability represents only one way of introducing the low-level, nonadaptive phenotypic trait variation that so favors conformist transmission, the other obvious way being learning errors, and (2) our findings apply to the evolution of conformist transmission in social interactions. Throughout we emphasize how our models generate empirical predictions suitable for laboratory testing. (shrink)

Using samples from three diverse populations, we test evolutionary hypotheses regarding how people reason about the inheritance of various traits. First, we provide a framework for differentiat-ing the outputs of mechanisms that evolved for reasoning about variation within and between biological taxa and culturally evolved ethnic categories from a broader set of beliefs and categories that are the outputs of structured learning mechanisms. Second, we describe the results of a modified “switched-at-birth” vignette study that we administered among children and adults (...) in Puno, Yasawa, and adults in the United States. This protocol permits us to study perceptions of prenatal and social transmission pathways for various traits and to differentiate the latter into vertical versus horizontal cultural influence. These lines of evidence suggest that people use all three mechanisms to reason about the distribution of traits in the population. Participants at all three sites develop expectations that morphological traits are under prenatal influence, and that belief traits are more culturally influenced. On the other hand, each population holds culturally specific beliefs about the degree of social influence on non-morphological traits and about the degree of vertical transmission—with only participants in the United States expecting parents to have much social influence over their children. We reinterpret people's differentiation of trait transmission pathways in light of humans' evolutionary history as a cultural species. (shrink)

Much existing literature in anthropology suggests that teaching is rare in non-Western societies, and that cultural transmission is mostly vertical (parent-to-offspring). However, applications of evolutionary theory to humans predict both teaching and non-vertical transmission of culturally learned skills, behaviors, and knowledge should be common cross-culturally. Here, we review this body of theory to derive predictions about when teaching and non-vertical transmission should be adaptive, and thus more likely to be observed empirically. Using three interviews conducted with rural Fijian populations, we (...) find that parents are more likely to teach than are other kin types, high-skill and highly valued domains are more likely to be taught, and oblique transmission is associated with high-skill domains, which are learned later in life. Finally, we conclude that the apparent conflict between theory and empirical evidence is due to a mismatch of theoretical hypotheses and empirical claims across disciplines, and we reconcile theory with the existing literature in light of our results. (shrink)

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. (shrink)

In two studies, 5- and 6-year-old children were questioned about the status of the protagonist embedded in three different types of stories. In realistic stories that only included ordinary events, all children, irrespective of family background and schooling, claimed that the protagonist was a real person. In religious stories that included ordinarily impossible events brought about by divine intervention, claims about the status of the protagonist varied sharply with exposure to religion. Children who went to church or were enrolled in (...) a parochial school, or both, judged the protagonist in religious stories to be a real person, whereas secular children with no such exposure to religion judged the protagonist in religious stories to be fictional. Children's upbringing was also related to their judgment about the protagonist in fantastical stories that included ordinarily impossible events whether brought about by magic or without reference to magic . Secular children were more likely than religious children to judge the protagonist in such fantastical stories to be fictional. The results suggest that exposure to religious ideas has a powerful impact on children's differentiation between reality and fiction, not just for religious stories but also for fantastical stories. (shrink)

Henrich and Boyd (2002) were the first to propose a formal model of the role of attraction in cultural evolution. They came to the surprising conclusion that, when both attraction and selection are at work, final outcomes are determined by selection alone. This result is based on a deterministic view of cultural attraction, different from the probabilistic view introduced in Sperber (1996). We defend this probabilistic view, show how to model it, and argue that, when both attraction and selection are (...) at work, both affect final outcomes. (shrink)

Formal models of cultural evolution analyze how cognitive processes combine with social interaction to generate the distributions and dynamics of ‘representations.’ Recently, cognitive anthropologists have criticized such models. They make three points: mental representations are non-discrete, cultural transmission is highly inaccurate, and mental representations are not replicated, but rather are ‘reconstructed’ through an inferential process that is strongly affected by cognitive ‘attractors.’ They argue that it follows from these three claims that: 1) models that assume replication or replicators are inappropriate, (...) 2) selective cultural learning cannot account for stable traditions, and 3) selective cultural learning cannot generate cumulative adaptation. Here we use three formal models to show that even if the premises of this critique are correct, the deductions that have been drawn from them are false. In the rst model, we assume continuously varying representations under the in uence of weak selective transmission and strong attractors. We show that if the attractors are suf ciently strong relative to selective forces, the continuous representation model reduces to the standard.. (shrink)

The belief in immanent justice is the expectation that the universe is designed to ensure that evil is punished and virtue rewarded. What makes this belief so ‘natural’? Here, we suggest that this intuition of immanent justice derives from our evolved sense of fairness. In cases where a misdeed is followed by a misfortune, our sense of fairness construes the misfortune as a way to compensate for the misdeed. To test this hypothesis, we designed a set of studies in which (...) we show that people who do not believe in immanent justice are nonetheless implicitly influenced by intuitions of immanent justice. Strikingly, this effect disappears when the misfortune is disproportionate compared to the misdeed: In this case, justice is not restored and participants lose the intuition of immanent justice. Following recent theories of religion, we suggest that this intuition contributes to the cultural success of beliefs in immanent justice. (shrink)

Religion is not an evolutionary adaptation per se, but a recurring by-product of the complex evolutionary landscape that sets cognitive, emotional and material conditions for ordinary human interactions. Religion involves extraordinary use of ordinary cognitive processes to passionately display costly devotion to counterintuitive worlds governed by supernatural agents. The conceptual foundations of religion are intuitively given by task-specific panhuman cognitive domains, including folkmechanics, folkbiology, folkpsychology. Core religious beliefs minimally violate ordinary notions about how the world is, with all of its (...) inescapable problems, thus enabling people to imagine minimally impossible supernatural worlds that solve existential problems, including death and deception. Here the focus is on folkpsychology and agency. A key feature of the supernatural agent concepts common to all religions is the triggering of an "Innate Releasing Mechanism," or “agency detector,” whose proper domain encompasses animate objects relevant to hominid survival - such as predators, protectors and prey - but which actually extends to moving dots on computer screens, voices in wind, faces on clouds. Folkpsychology also crucially involves metarepresentation, which makes deception possible and threatens any social order; however, these same metacognitive capacities provide the hope and promise of open-ended solutions through representations of counterfactual supernatural worlds that cannot be logically or empirically verified or falsified. Because religious beliefs cannot be deductively or inductively validated, validation occurs only by ritually addressing the very emotions motivating religion. Cross-cultural experimental evidence encourages these claims. (shrink)

Understanding religion requires explaining why supernatural beliefs, devotions, and rituals are both universal and variable across cultures, and why religion is so often associated with both large-scale cooperation and enduring group conflict. Emerging lines of research suggest that these oppositions result from the convergence of three processes. First, the interaction of certain reliably developing cognitive processes, such as our ability to infer the presence of intentional agents, favors—as an evolutionary by-product—the spread of certain kinds of counterintuitive concepts. Second, participation in (...) rituals and devotions involving costly displays exploits various aspects of our evolved psychology to deepen people's commitment to both supernatural agents and religious communities. Third, competition among societies and organizations with different faith-based beliefs and practices has increasingly connected religion with both within-group prosociality and between-group enmity. This connection has strengthened dramatically in recent millennia, as part of the evolution of complex societies, and is important to understanding cooperation and conflict in today's world. (shrink)

An invited commentary on Ara Norenzayan's Big Gods: How Religion Transformed Cooperation and Conflict, focusing on whether early China constitutes an exception to his general theory.