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Many rumors convey information about potential danger, even when these dangers are very unlikely. In four studies, we examine whether micro-processes of cultural transmission explain the spread of threat-related information. Three studies using transmission chain protocols suggest a) that there is indeed a preference for the deliberate transmission of threat-related information over other material, b) that it is not caused by a general negativity or emotionality bias, and c) that it is not eliminated when threats are presented as very unlikely. A forced-choice study on similar material shows the same preference when participants have to select information to acquire rather than transmit. So the cultural success of threat-related material may be explained by transmission biases, rooted in evolved threat-detection and error-management systems, that affect both supply and demand of information.

Understanding patterns and underlying processes of human cultural diversity has been a major challenge in evolutionary anthropology. Recent developments in the study of cultural macro-evolution have illuminated various novel aspects of cultural phenomena at the population level. However, limitations in data availability have constrained previous analyses to use simplest models ignoring factors that potentially affect cultural evolutionary dynamics. Here, we focus on two such factors: accumulated effects of cultural transmission between populations over time and variation in social influence among populations. As a test case, we analyze data on the hinoeuma fertility drop, the Japanese nation-wide drastic decline in the number of births caused by a culturally-transmitted superstition recurring every sixty years, to show that these factors do play significant roles. Specifically, our results suggest that transmission of the superstition in a short timescale has tended to occur among neighboring populations, while transmission in a long timescale is likely to have occurred between populations culturally close to each other, with the cultural closeness being measured by similarity in dialects. The results also indicate a special role played by a population occupying a center in a language–distance network (the cultural center) in the spread of the superstition.

There exist striking resemblances in the stories of ethnolinguistic groups separated by vast geographic distances, with nearby groups having the most in common. The causes of these geographic associations are uncertain. Here we use method and theory from population genetics to examine cultural transmission in folktale inventories of 18 hunter–gatherer groups spread across 6000km of Siberia, Alaska, Canada, and Greenland. We find that linguistic relatedness and geographic proximity independently predict overlap in folktale inventories, which provides evidence for both vertical transmission down cultural lineages and horizontal transmission between groups. These results suggest that high-bandwidth social learning across group boundaries is a feature of traditional hunter–gatherers, which may help explain how complex cultural traditions can develop and be retained in ostensibly small groups.

Children will comprehensively copy others' actions despite manifest perceptual cues to their causal ineffectiveness. In experiment 1 we demonstrate that children will overimitate in this way even when the arbitrary actions copied are used as part of a process to achieve an outcome for someone else. We subsequently show in experiment 2 that children will omit arbitrary actions, but only if the actions are to achieve a clear, functional goal for a naive adult. These findings highlight how readily children adopt what appear to be conventional behaviors, even when faced with a clear demonstration of their negligible functional value. We show how a child's strong, early-emerging propensity for overimitation reveals a sensitivity for ritualistic behavior.

Evolutionary theorists argue that cultural evolution has harnessed various aspects of our evolved psychology to create a variety of different mechanisms for sustaining social norms, including those related to large-scale cooperation. One of these mechanisms, costly punishment, has emerged in experiments as an effective means to sustain cooperation in some societies. If this view is correct, individuals' willingness to engage in the costly punishment of norm violators should be culturally transmittable, and applicable to both prosocial and anti-social behaviors (to any social norm). Since much existing work shows that norm-based prosocial behavior in experiments develops substantially during early and middle childhood, we tested 245 3- to 8-year olds in a simplified third party punishment game to investigate whether children would imitate a model's decision to punish, at a personal cost, both unequal and equal offers. Our study showed that children, regardless of their age, imitate the costly punishment of both equal and unequal offers, and the rates of imitation increase (not decrease) with age. However, only older children imitate not-punishing for both equal and unequal offers. These findings highlight the potential role of cultural transmission in the stabilization or de-stabilization of costly punishment in a population.

The neutral model of cultural evolution, which assumes that copying is unbiased, provides precise predictions regarding frequency distributions of traits and the turnover within a popularity-ranked list. Here we study turnover in ranked lists and identify where the turnover departs from neutral model predictions to detect transmission biases in three different domains: color terms usage in English language 20th century books, popularity of early (1880–1930) and recent (1960–2010) USA baby names, and musical preferences of users of the Web site Last.fm. To help characterize the type of transmission bias, we modify the neutral model to include a content-based bias and two context-based biases (conformity and anti-conformity). How these modified models match real data helps us to infer, from population scale observations, when cultural transmission is biased, and, to some extent, what kind of biases are operating at individual level.

The role of cultural group selection in the evolution of human cooperation is hotly debated. It has been argued that group selection is more effective in cultural evolution than in genetic evolution, because some forms of cultural transmission (conformism and/or the tendency to follow a leader) reduce intra-group variation while creating stable cultural variation between groups. This view is supported by some models, while other models lead to contrasting and sometimes opposite conclusions. A consensus view has not yet been achieved, partly because the modelling studies differ in their assumptions on the dynamics of cultural transmission and the mode of group selection. To clarify matters, we created an individual-based model allowing for a systematic comparison of how different social learning rules governing cultural transmission affect the evolution of cooperation in a group-structured population. We consider two modes of group selection (selection by group replacement or by group contagion) and systematically vary the frequency and impact of group-level processes. From our simulations we conclude that the outcome of cultural evolution strongly reflects the interplay of social learning rules and the mode of group selection. For example, conformism hampers or even prevents the evolution of cooperation if group selection acts via contagion; it may facilitate the evolution of cooperation if group selection acts via replacement. In contrast, leader-imitation promotes the evolution of cooperation under a broader range of conditions. (C) 2013 Elsevier Inc. All rights reserved.

article i nfo Migration is a major feature of past and especially today's globalized cultures, and understanding how migration shapes cultural groups is key to the empirical applications of cultural transmission theory. Developed here is a migration-assimilation model describing the population-level dynamics of diaspora culture. Using ethnographic data collected from 2009 to 2010 in the Kingdom of Tonga and a Tongan diaspora community, key parameters of the model were estimated and the fitted model simulated to describe diaspora cultural dynamics in the Tongan case. The relative contribution of recent migrants to the population-level expression of several cultural traits is highlighted in the simulation. Results show that the dependence on the Tongan homeland as a source of conservative culture through migration is variable and trait specific. For traits with higher assimilation rates, the contribution of recent Tongan migrants is substantial, while for other traits with lower assimilation rates, the influence of Tongan migrants is muted. Preliminary hypotheses to explain the trait-specific assimilation rates are discussed.

Natural selection is likely to have shaped developmental systems for rapid acquisition of knowledge about environmental dangers, including dangerous animals. However, learning about dangerous animals through direct encounters can be costly and potentially fatal. In social species such as humans, the presence of stored information about danger in the minds of conspecifics might favor the evolution of prepared social learning mechanisms that cause children to preferentially attend to and remember culturally transmitted information about danger. Here we use an experimental learning task to show that children from two very different cultures exhibit prepared social learning about dangerous animals: city-dwelling children from Los Angeles, who face relatively little danger from animals, and Shuar children from the Amazon region of Ecuador, to whom dangerous animals pose a much greater threat. Both populations exhibited similar prepared learning effects. Danger information was learned in a single trial without feedback, immediately entered long-term memory, and was recalled with only minor attenuation a week later, while other information presented at the same time (animal names and diets) was immediately forgotten. We discuss the significance of these design features of prepared learning in light of the phylogeny and function of danger learning systems.

Recent mathematical modeling of repeated cultural transmission has shown that the rate at which culture is lost (due to imperfect transmission) will crucially depend on whether individuals receive transmissions from many cultural parents or only from one. However, the modeling assumptions leading up to this conclusion have so far not been empirically assessed. Here we do this for the special case of transmission chains where each individual either receives the same story twice from one cultural parent (and retransmits twice to a cultural child) or receives possibly different versions of the story from two cultural parents (and then retransmits to two cultural children). For this case, we first developed a more general mathematical model of cultural retention that takes into account the possibility of dependence of error rates between transmissions. In this model, under quite plausible assumptions, chains with two cultural parents will have superior retention of culture. This prediction was then tested in two experiments using both written and oral modes of transmission. In both cases, superior retention of culture was found in chains with two cultural parents. Estimation of model parameters indicated that error rates were not identical and independent between transmissions; instead, a primacy effect was suggested, such that the first transmission tends to have higher fidelity than the second transmission.

Cumulative cultural evolution requires that information is faithfully transmitted from generation to generation. The present study examines the role of agent interaction as a social learning mechanism through which information is transmitted across multiple generations. The performance of two types of linear transmission chains was compared: noninteractive (agents in adjacent chain positions were not permitted to interact) and interactive (adjacent agents freely interacted with one another). In both conditions, information (details of a narrative text) was lost as it was passed along the transmission chain. However, interactive transmission chains promoted more accurate recall of information than noninteractive chains. A content analysis revealed that most listeners actively participated in the information transfer process by seeking clarification and providing backchannel feedback to the narrator. Furthermore, the extent to which listeners engaged with the narrator was associated with narrator recall accuracy. Our results indicate that bidirectional agent interaction is an important consideration for studies of cultural transmission and cumulative cultural evolution.

The modeling of cultural transmission is of great importance for understanding the maintenance, erosion, and spread of cultural traits and innovations. Researchers have hypothesized that, unlike biological transmission, cultural transmission occurs through at least three different, non-mutually exclusive paths: (1) from parents (vertical); (2) from age peers (horizontal); and (3) from older generations (oblique). We used data from 270 adults in a society in the Bolivian Amazon to estimate the association between a person's knowledge and skills and the knowledge and skills of the (1) same-sex parent, (2) age peers (or individuals born in the same village as the subject within ±4 years of the subject's year of birth), and (3) parental cohort (excluding parents). We found a statistically significant association between personal and parental and old cohort knowledge. The magnitude of the association is larger for old cohort knowledge than for parental knowledge, suggesting that, for the studied population, the transmission of ethnobotanical knowledge and skills is mostly oblique.

This paper lays out an evolutionary theory for the cognitive foundations and cultural emergence of the extravagant displays (e.g., ritual mutilation, animal sacrifice and martyrdom) that have so tantalized social scientists, as well as more mundane actions that influence cultural learning and historical processes. In Part I, I use the logic of natural selection to build a theory for how and why seemingly costly displays influence the cognitive processes associated with cultural learning — why do “actions speak louder than words?” The core idea is that cultural learners can both avoid being manipulated by their models (those they are inclined to learn from) and more accurately assess their belief commitment by attending to displays or actions by the model that would seem costly to the model if he held beliefs different from those he expresses verbally. Part II examines the implications for cultural evolution of this learning bias in a simple evolutionary model. The model reveals the conditions under which this evolved bias can create stable sets of interlocking beliefs and practices, including quite costly practices. Part III explores how cultural evolution, driven by competition among groups or institutions stabilized at alternative sets of these interlocking belief-practice combinations, has led to the association of costly acts, often in the form of rituals, with deeper commitments to group beneficial ideologies, higher levels of cooperation within groups, and greater success in competition with other groups or institutions. I close by discussing the broader implications of these ideas for understanding various aspects of religious phenomena.

Previous evolutionary analyses of human culture have found that a simple model of random copying, analogous to neutral genetic drift, can generate the distinct power-law frequency distribution of cultural traits that is typical of various real-world cultural datasets, such as first names, patent citations and prehistoric pottery types. Here, we use agent-based simulations to explore the effects of frequency-dependent copying (e.g., conformity and anti-conformity) on this power-law distribution. We find that when traits are actively selected on the basis of their frequency, then the power-law distribution is severely disrupted. Conformity generates a “winner-takes-all” distribution in which popular traits dominate, while anti-conformity generates a “humped” distribution in which traits of intermediate frequency are favoured. However, a more passive frequency-dependent “trimming”, in which traits are selectively ignored on the basis of their frequency, generates reasonable approximations to the power-law distribution. This frequency-dependent trimming may therefore be difficult to distinguish from genuine random copying using population-level data alone. Implications for the study of both human and nonhuman culture are discussed.

An experimental simulation of cultural evolution was conducted using the virtual arrowhead task. Participants designed “virtual arrowheads” and tested them in “virtual hunting environments”, improving their designs through either individual trial-and-error learning or by copying the design of another participant. A previous study using this task [Mesoudi, A., & O'Brien, M. J. (2008). The cultural transmission of Great Basin projectile point technology I: An experimental simulation. American Antiquity, 73, 3–28.] found that a cultural learning strategy of “copy-successful-individuals” was significantly more adaptive than individual learning. The present study explored the robustness of this finding using the same task but under different conditions. It was found that (a) individual learning was significantly more adaptive in a unimodal adaptive landscape than in a multimodal adaptive landscape, suggesting that the adaptive advantage of cultural learning would disappear in unimodal environments; (b) the adaptive advantage of copy-successful-individuals was maintained when cultural learning was permitted at regular intervals, despite the increased opportunity for information scroungers to inhibit exploration of the environment, because participants flexibly switched between individual and cultural learning depending on circumstances; (c) allowing participants to set access costs that other participants must pay in order to view their designs severely curtailed the use of cultural learning and especially the copy-successful-individuals strategy.

The propensity to imitation over other forms of learning is one of the major differences between humans and other species and one that has allowed for cumulative cultural evolution. However, imitation alone cannot explain increases of average fitness in human populations. Anthropologists have hypothesized that people do not imitate behaviors from random people; rather, transmission of some cultural traits (e.g., healing skills) follows biases designed to extract reproductive benefit from the flow of socially transmitted information. In an article in this journal, Henrich and Gil-White argued that important sources of bias in the acquisition of culturally transmitted information come from prestige processes. Here, we test predictions from the prestige-bias model of cultural transmission. We use quantitative information on ethnomedicinal plant knowledge of adult (age >16) Tsimane' men ( n =288) collected during 2005. To measure prestige, we asked Tsimane' to list important villagers and counted the number of nominations each person received. We find weak evidence that prestige is associated with ethnomedicinal plant knowledge, and we find no evidence that prestige is associated with age. Rather, we find a secular decline in prestige by decade of birth. Last, prestige bears a positive association with other attributes, such as participation in village organizations. Future empirical research needs to decouple power from prestige.

The rapid appearance (over evolutionary time) of the cognitive skills and complex inventions of modern humans has been attributed to “cumulative cultural evolution” (CCE), the accumulation of knowledge and skills over generations. To date, researchers have only been able to speculate about the reasons for the apparent absence of this phenomenon in nonhumans, and it has not been possible to test hypotheses regarding the mechanisms underlying it. Here, we show that it is possible to demonstrate CCE under laboratory conditions by simulating generational succession through the repeated removal and replacement of human participants within experimental groups. We created “microsocieties” in which participants were instructed to complete simple tasks using everyday materials. In one of our procedures, participants were instructed to build a paper aeroplane which flew as far as possible, and in the other, they were instructed to construct a tower of spaghetti which was as tall as possible. We show that, in both cases, information accumulates within the groups such that later generations produce designs which are more successful than earlier ones. These methods offer researchers a window to understanding CCE, allowing for experimental manipulation and hypothesis testing.

Conformity is a type of social learning that has received considerable attention among social psychologists and human evolutionary ecologists, but existing empirical research does not identify conformity cleanly. Conformity is more than just a tendency to follow the majority; it involves an exaggerated tendency to follow the majority. The "exaggerated" part of this definition ensures that conformists do not show just any bias toward the majority, but a bias sufficiently strong to increase the size of the majority through time. This definition of conformity is compelling because it is the only form of frequency-dependent social influence that produces behaviorally homogeneous social groups. We conducted an experiment to see if players were conformists by separating individual and social learners. Players chose between two technologies repeatedly. Payoffs were random, but one technology had a higher expected payoff. Individual learners knew their realized payoffs after each choice, while social learners only knew the distribution of choices among individual learners. A subset of social learners behaved according to a classic model of conformity. The remaining social learners did not respond to frequency information. They were neither conformists nor nonconformists, but mavericks. Given this heterogeneity in learning strategies, a tendency to conform increased earnings dramatically.

The relationship between self-esteem and aggression has yielded mixed results and generated much recent debate in the social psychology literature. Based on an evolutionary-psychological theory of self-esteem, Kirkpatrick et al. [Kirkpatrick, L. A., Waugh, C. E., Valencia, A., Webster, G., 2002. The functional domain-specificity of self-esteem and the differential prediction of aggression. Journal of Personality and Social Psychology 825, 756–767] showed that multiple, functionally distinct self-esteem mechanisms predict aggression differentially: e.g., "self-perceived superiority" is positively related, and "social inclusion" inversely related, to behavioral aggression. The present study extends this research by further differentiating two distinct forms of "superiority," dominance and prestige [Henrich, J., Gil-White, F. J. 2001. The evolution of prestige: Freely conferred deference as a mechanism for enhancing the benefits of cultural transmission. Evolution and Human Behavior 22, 165–196], in the prediction of aggression in men and women and testosterone levels (measured in saliva samples) in men. Dominance was positively related, but prestige was either unrelated or inversely related, to self-report aggression measures. Dominance was unrelated but prestige inversely related to testosterone levels in men, perhaps suggesting a method of testosterone inhibition in individuals attaining prestige-based superiority. In addition to contributing to the growing literature on the aggression–self-esteem link, the results provide validation for the prestige–dominance distinction and support, but also suggest an important refinement to, a theory of self-esteem as a collection of functionally distinct adaptations.

Almost by definition, “popular culture” reflects the effects of most people imitating those around them. At the same time, trends and fashions are constantly changing, with future outcomes potentially irrational and nearly impossible to predict. A simple null model, which captures these seemingly conflicting tendencies of conformity and change, involves the random copying of cultural variants between individuals, with occasional innovation. Here, we show that the random-copying model predicts a continual flux of initially obscure new ideas (analogous to mutations) becoming highly popular by chance alone, such that the turnover rate on a list of most popular variants depends on the list size and the amount of innovation but not on population size. We also present evidence for remarkably regular turnover on “pop charts”—including the most popular music, first names, and dog breeds in 20th-century United States—which fits this expectation. By predicting parametric effects on the turnover of popular fashion, the random-copying model provides an additional means of characterizing collective copying behavior in culture evolution.

The theory of cultural transmission distinguishes between biased and unbiased social learning. Biases simply mean that social learning is not completely random. The distinction is critical because biases produce effects at the aggregate level that then feed back to influence individual behavior. This study presents an economic experiment designed specifically to see if players use social information in a biased way. The experiment was conducted among a group of subsistence pastoralists in southern Bolivia. Treatments were designed to test for two widely discussed forms of biased social learning: a tendency to imitate success and a tendency to follow the majority. The analysis, based primarily on fitting specific evolutionary models to the data using maximum likelihood, found neither a clear tendency to imitate success nor conformity. Players instead seemed to rely largely on private feedback about their own personal histories of choices and payoffs. Nonetheless, improved performance in one treatment provides evidence for some important but currently unspecified social effect. Given existing experimental work on cultural transmission from other societies, the current study suggests that social learning is potentially conditional and culturally specific.

From the history of mathematics, it is clear that some numerical concepts are far more pervasive than others. In a densely multimodular mind, evolved cognitive abilities lie at the basis of human culture and cognition. One possible way to explain the differential spread and survival of cultural concepts based on this assumption is the epidemiology of culture. This approach explains the relative success of cultural concepts as a function of their fit with intuitions provided by conceptual modules. A wealth of recent evidence from animal, infant, and neuroimaging studies suggests that human numerical competence is rooted in an evolved number module. In this study, I adopted an epidemiological perspective to examine the cultural transmission of numerical concepts in the history of mathematics. Drawing on historical and anthropological data on number concepts, I will demonstrate that positive integers, zero, and negative numbers have divergent cultural evolutionary histories owing to a distinct relationship with the number module. These case studies provide evidence for the claim that science can be explained in terms of evolved cognitive abilities that are universal in Homo sapiens. ispartof: Evolution and human behavior vol:27 issue:4 pages:306-323 ispartof: location:ITALY, Stresa status: published

It is often taken for granted that social/cultural learning increases human adaptability, because it allows us to acquire useful information without costly individual learning by trial and error. Rogers [Am. Anthropol. 90 (1988) 819] challenged this common view by a simple analytic model. Assuming a "cultural" population composed of individual learners engaging in costly information search and imitators who just copy another member's behavior, Rogers showed that mean fitness of such a mixed "cultural" population at the evolutionary equilibrium is exactly identical to the mean fitness of an "acultural" population consisting only of individual learners. Rogers's result implies that no special adaptive advantage accrues from social/cultural learning. We revisited this counterintuitive argument through use of an experiment with human subjects, and by a series of evolutionary computer simulations that extended Kameda and Nakanishi [Evol. Hum. Behav. 23 (2002) 373]. The simulation results indicated that, if agents can switch between individual learning and imitation selectively, a "cultural" population indeed outperforms an "acultural" population in mean fitness for a broad range of parameters. An experiment that implemented a nonstationary uncertain environment in a laboratory setting provided empirical support for this thesis. Implications of these findings for cultural capacities and some future directions are discussed.

Social/cultural learning is an effective way to reduce uncertainty about the environment, helping individuals adopt an adaptive behavior cheaply. Although this is evident for learning about temporally stable targets, such as acquisition of a skill in avoiding toxic foods, the utility of social/cultural learning in a temporally unstable environment is less clear, since knowledge acquired by social learning may be outdated. This paper addresses the adaptive value of social/cultural learning in a nonstationary environment both theoretically and empirically. We first conducted an evolutionary computer simulation that extended Henrich and Boyd's [Evol. Hum. Behav. 19 (1998) 215.] model of cultural transmission, with the following results. When individual learning about the nonstationary environment is costly, a mixed equilibrium emerges in the population, where members who engage in costly individual learning and members who skip the information search and free-ride on other members' search efforts coexist at a stable ratio. Such a "producer–scrounger" structure qualifies effectiveness of social/cultural learning severely, especially "conformity bias" when using social information. We then tested these propositions by an experiment implementing a nonstationary uncertain environment in a laboratory. The results supported our thesis. Implications of these findings and some future directions are discussed.

Narrative is a species-typical, reliably developing, complex cognitive process whose design is unlikely to have emerged by chance. Moreover, the folklore record indicates that narrative content is consistent across widely divergent cultures. I have argued elsewhere that a storyteller may use narrative to manipulate an audience's representations of the social and/or physical environment to serve his or her own fitness ends. However, my subsequent research suggests that such manipulation results from a broader selection pressure which narrative effectively alleviates: information acquisition. By substituting verbal representations for potentially costly first-hand experience, narrative enables an individual to safely and efficiently acquire information pertinent to the pursuit of fitness in local habitats. If this hypothesis is true, narrative should be rich with information useful to the pursuit of fitness. One class of information integral to the accomplishment of this task is foraging knowledge. In this paper, then, I present evidence that foraging peoples use narrative to transmit subsistence information: specifically, I demonstrate how various narrative devices (e.g., setting, description, mimicry, anthropomorphism) are used to communicate foraging knowledge.

Unlike other animal species, much of the variation among human groups is cultural: genetically similar people living in similar environments exhibit strikingly different patterns of behavior because they have different, culturally acquired beliefs and values. Such cultural transmission is based on complex, derived psychological mechanisms that are likely to have been shaped by natural selection. It is important to understand the nature of these evolved psychological mechanisms because they determine which beliefs and values spread and persist in human groups. Boyd and Richerson showed that a tendency to acquire the most common behavior exhibited in a society was adaptive in a simple model of evolution in a spatially varying environment, because such a tendency increases the probability of acquiring adaptive beliefs and values. Here, we study the evolution of such “conformist transmission” in a more general model in which environments vary in both time and space. The analysis of this model indicates that conformist transmission is favored under a very broad range of conditions, broader in fact than the range of conditions that favor a substantial reliance on social learning. The analysis also suggests that there is a synergistic relationship between the evolution of imitation and the evolution of conformism. We conclude by examining the role of conformism in explaining the maintenance of cultural differences among groups.

It is often assumed that parent-to-child cultural transmission leads to similarities and differences among groups evolving through descent with modification ("phylogenesis"). Similarly, cultural transmission between peers, and between adults and children who are not their offspring, is widely believed to result in groups exchanging cultural traits ("ethnogenesis"). However, neither of these assumptions has been examined empirically. Here we test them using ethnographic data on craft learning in Iranian tribal populations and the cladistic method of phylogenetic analysis. We find that parent-to-child transmission dominates learning during childhood, but the other two forms of inter-individual transmission become more important in later periods. The latter do not, however, appear to have resulted in extensive exchange of cultural traits among tribes. Instead we find that most of the variation among the tribes' craft assemblages can be explained by descent with modification. This can be accounted for by the fact that weavers usually only share their knowledge with members of their own tribe and are prevented from interacting with women from other groups by social norms. These findings demonstrate that the relationship between processes of cultural evolution at the level of the individual and processes of cultural evolution at the level of the group is more complex than is usually acknowledged, and highlight the need for more integrated studies of the processes operating at both scales.