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Despite the indisputable significance of human symbolic cognition and behavior, we still lack a detailed understanding of the mechanisms by which such capacities evolved during the Paleolithic. An important source of evidence is constituted by archaeological findings of intentional markings left on rock and bone surfaces, but these are often opaque with respect to their original meaning and function. Here we present experimental work that systematically addresses the relation between properties of intentional markings and their cognitive implications to support inferences about their past functions. Participants reproduced engraved markings dating to c. 100.000 years ago from the South African Blombos and Diepkloof sites in three conditions of cultural transmission: as part of an aesthetic, identity marking, and communicative activity. Their reproductions were then used as stimuli in a suite of five perceptual experiments to investigate differences in their cognitive implications over time and explore similarities with the archaeological record. [ABSTRACT FROM AUTHOR]

Occupation of the foraging niche requires an extensive body of ecological knowledge, and humans rely heavily on social learning to master this curriculum in a safe, efficient, timely manner. This presents a formidable information management problem: In the absence of writing, how did ancestral hunter-gatherer societies accurately store and transmit their accumulated knowledge from generation to generation? Pronounced patterns in forager oral story corpora suggest a partial answer. Cross-culturally, these stories exhibit similar themes, genres, and characters, which in turn map onto critical domains of ecological knowledge. These stories also exhibit pronounced consistencies in their formal properties, predictably utilizing strategies that engage attention (e.g., ostensive communication) and facilitate memorization (e.g., repetition, rhythm, imagery). These patterns suggest that storytelling is an information technology that addresses key problems posed by our entry into the information niche: in conjunction with other forms of symbolic behavior (e.g., ritual, visual art, song, dance, games) storytelling provides a mnemonic framework for encoding accumulated knowledge, rules for faithfully copying it, and regular occasions for refreshing and transmitting it. Collectively, these behaviors may have been instrumental in the emergence of cumulative culture. [ABSTRACT FROM AUTHOR]

For most of human evolution, accumulated cultural knowledge has been stored in memory and transmitted orally. This presents a daunting information management problem: how to store and transmit this knowledge in a portable format that resists corruption. One solution–widespread among foragers–is to encode knowledge in narrative. However, this strategy depends on accurate performance of the story. Significantly, some forager cultures have rules regulating myth performance, although the extent of this phenomenon is unknown. We hypothesize that these rules subserve high-fidelity transmission across generations. Accordingly, we predicted that, across forager cultures, myth-telling rules will mandate: (P1) transmission by the most proficient storytellers (P2) under low-distraction conditions with (P3) multiple individuals and (P4) multiple generations present, and the application of measures that (P5) prevent, identify, and/or correct errors, (P6) maintain audience attention, (P7) discourage rule violations and/or (P8) incentivize rule compliance. To test these predictions, we searched the forager ethnographic record for descriptions of myth performance, and coded them for prescriptions/proscriptions regarding narrator age, performance context, audience composition, narrative delivery, and audience comportment, as well as sanctions associated with rule transgression or compliance. Results indicate that rules regulating myth performance are widespread across forager cultures, and are characterized by features that reduce the likelihood of copy errors. These findings help elucidate the role that anthropogenic ratchets played in the emergence of cumulative culture. [ABSTRACT FROM AUTHOR]

Humans transmit cultural information to others in a variety of ways that can affect productivity, cultural success, and ultimately fitness. Not all potential transmitters are expected to be equally preferred by learners or equally willing to influence their culture acquisition. Across socioeconomic opportunities and ages in the human life course, costs and benefits to both learners and potential transmitters are expected to vary, affecting rates of culture transmission from different vectors. Here we examine reported patterns of culture transmission contributing to 92 essential skills among a sample of 421 Tsimane forager-farmers native to Bolivia. Consistent with the expectation that the costly provision of support and cultural information typically flows from older to younger generations in a subsistence society, we find that the development of essential knowledge and skills is primarily influenced by older same-sex relatives, especially parents. Grandparents are more often reported as transmitters for low-strength/high-difficulty skills that they have comparative advantage in, such as storytelling and musical performance. Though less frequent, same generation peers are more likely to provide discouragement in the learning process and to transmit modern, market-oriented skills. Our findings suggest that kinship, gender, generational seniority, and skill type together explain the vectors and styles of influence responsible for essential culture transmission. The multigenerational pedagogy documented here helps facilitate successful economic and social production in a complex skills niche dependent on multigenerational cooperation, such as observed in human hunter-gatherers and other subsistence populations. • We study reports of cultural transmission vectors and styles of influence. • Knowledge and skills are primarily influenced by older same-sex relatives. • Parents contribute the most to traditional skill transmission. • Older relatives tend to transmit low-strength/high-difficulty traditional skills. • Same-generation peers tend to transmit modern and market skills. [ABSTRACT FROM AUTHOR]

Music is a product of both biological and cultural evolution. Cultural transmission is the engine of cultural evolution and may play a role in the establishment of musical universals. Here, we examined how transmission dynamics can shape melodic features in music. Specifically, we tested whether random melodic seeds, in their transformation, take on properties known to characterise music within or even across cultures. Using an iterated learning paradigm, we investigated the transmission of random melodic seeds through a chain of non-musician participants (N = 64). We found that melodies reproduced vocally between "generations" became more similar to known musical scales, exhibited a predominance of consonant intervals, and reduced the number of scale degrees used. Additionally, we observed the previously documented tendency for large intervals to be followed by a change in direction, as well as features common to both music and speech including phrase-final lengthening and the Zipfian distribution of signalling units. As participants' vocalisations converged towards greater memorability, they exhibited decreased entropy, and their contours became smoother and more consistent. Finally, certain short melodic patterns became prominent motifs within the incipient musical "traditions" simulated by the chains. These emerging features may reflect a process shaped by (i) cognitive bottlenecks such as learnability; (ii) statistical properties of the processes and structures involved in inter-generational vocal transmission; but also by (iii) idiosyncratic cultural artefacts specific to the lab samples employed. Overall, our results demonstrate that fundamental aspects of melodic structure emerge naturally through the process of cultural transmission, as simulated in the lab. [ABSTRACT FROM AUTHOR]

Humans, unlike any other species, have adapted to diverse environments across the globe due to cultural knowledge, skills, and practices. In early childhood, parent–child interactions play a pivotal role in cultural learning, but controversies about what constitutes teaching have stymied the systematic assessment of variation and similarities in parental teaching across cultures. We used a functional definition of teaching as behavior that evolved to facilitate learning in others and observed parents and their two-year-old child (N = 106) in a standardized setting (mealtime) in five diverse cultural contexts (rural: Brazil, Ecuador; urban: Argentina, Germany, Japan). Detailed coding of parental teaching (8520 teaching events in 1898 min of interactions) revealed that six teaching behaviors (prompts to do, prompts to stop, abstract communication of knowledge, demonstrations, providing choices, negative feedback) occurred frequently (> 5%) across contexts. At the same time, we found that the relative frequencies of these behaviors varied between contexts: Parents in rural contexts frequently used prompts towards their children. Parents in urban contexts often used abstract communication, demonstrations, and the provision of choices. We also identified nuanced differences between the urban samples regarding parental demonstrations (Japan) and the provision of choices (Germany). Our findings suggest that parents from all contexts mainly relied on a set of six teaching behaviors but that there was cross-cultural variation in how frequently behaviors occurred. Our study provides a cultural map of children's early learning experiences which lay the ontogenetic foundation for human cultural diversity. [ABSTRACT FROM AUTHOR]

Cognitive and evolutionary research has focused on the powerful deities of large-scale societies, yet little work has examined the smaller gods of animist traditions. In a study of the water spirit Sikameinan of the Mentawai people (Siberut Island, Indonesia), we address three questions: (1) Are smaller gods believed to enforce cooperation, especially compared to bigger gods in larger-scale societies? (2) Do beliefs in these deities encourage people to engage in behavior otherwise perceived as costly? and (3) Does ritual reinforce beliefs in these deities? Drawing on interview responses, data from healing ceremonies, and ethnographic observation, we show that Sikameinan is believed to punish people who violate meat-sharing norms and that people 'attacked' by Sikameinan pay shamans to conduct healing rituals. The public nature of rituals, involving prestigious individuals apologizing to Sikameinan for the patient's stinginess, reinforce onlookers' beliefs about Sikameinan. The most widely shared beliefs about Sikameinan are represented in rituals while beliefs not represented vary considerably, indicating that ritual may be potent for cultural transmission. These results suggest that moralizing supernatural punishers may be more common than suspected and that the trend in the cultural evolution of religion has been an expansion of deities' scope, powers, and monitoring abilities. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Several theoretical approaches have been proposed to explain variation in religiosity, including versions of secularization hypotheses, evolved cognitive biases, and cultural transmission. In this paper we test several theories that aim to explain variation in religiosity and compare them in a representative sample collected in the Czech Republic and Slovakia (N = 2022). These two countries represent a natural experiment in religiosity; despite their high level of historical, institutional and cultural similarity, their populations differ markedly in the rate of religious belief. We examine the predictive power of cognitive biases (anthropomorphism, dualism, teleology, mentalizing, and analytic thinking); institutional insecurity; and exposure to credibility displays of belief in childhood on various factors of religious belief. We find that individual differences in cognitive biases predicted 8% of the variance belief in God, but predicted 21% of the variance in paranormal beliefs and almost no variance in religious participation. Perceived institutional insecurity explains little variance in any of these variables, but cultural transmission, measured as exposure to credibility enhancing displays (CREDs) and church attendance in childhood, predicted 17% of the variance in belief in God and 30% of religious participation, and mediated 70% of the difference between these two countries in belief in God and 80% of the difference in religious practice. These findings suggest cognitive biases may explain the existence of belief in the supernatural generally, but cultural transmission through credible belief displays is a more plausible explanation for why people adopt and maintain a specific set of religious beliefs and practices. [ABSTRACT FROM AUTHOR]

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 naïve 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. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Abstract: Cumulative culture is thought to have played a major role in hominin evolution, and so an understanding of the factors that affect cultural accumulation is important for understanding human evolution. Population size may be one such factor, with larger populations thought to be able to support more complex cultural traits. This hypothesis has been suggested by mathematical models and empirical studies of small-scale societies. However, to date there have been few experimental demonstrations of an effect of population size on cultural accumulation. Here we provide such a demonstration using a novel task, solving jigsaw puzzles. 80 participants divided into ten transmission chains solved puzzles in one of two conditions: one in which participants had access to one semi-completed puzzle from the previous generation, and the other in which participants simultaneously saw three semi-completed puzzles from the previous generation. As predicted, the mean number of pieces solved increased over time in the three-puzzle-per-generation condition, but not in the one-puzzle-per-generation condition. Thus, our experiment provides support for a hypothesized relationship between population size and cultural accumulation. In particular, our results suggest that the ability to simultaneously learn from multiple cultural models, and combine the knowledge of those multiple models, is most likely to allow larger groups to support more complex culture. [Copyright &y& Elsevier]

Abstract: We explore how cultural heterogeneity evolves without strong selection pressure or environmental differences between groups. Using a neutral transmission model with an isolation-by-distance spatiality, we test the effect of a simple representation of cultural ‘memory’ on the dynamics of heterogeneity. We find that memory magnifies the effect of affinity while decreasing the effect of individual learning on cultural heterogeneity. This indicates that, while the cost of individual learning governs the frequency of individual learning, memory is important in governing its effect. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: The use of social information is a prerequisite to the evolution of culture. In humans, social learning allows individuals to aggregate adaptive information and increase the complexity of technology at a level unparalleled in the animal kingdom. However, the potential to use social information is related to the availability of this type of information. Although most cultural evolution experiments assume that social learners are free to use social information, there are many examples of information withholding, particularly in ethnographic studies. In this experiment, we used a computer-based cultural game in which players were faced with a complex task and had the possibility to trade a specific part of their knowledge within their groups. The dynamics of information transmission were studied when competition was within- or exclusively between-groups. Our results show that between-group competition improved the transmission of information, increasing the amount and the quality of information. Further, informational access costs did not prevent social learners from performing better than individual learners, even when between-group competition was absent. Interestingly, between-group competition did not entirely eliminate access costs and did not improve the performance of players as compared with within-group competition. These results suggest that the field of cultural evolution would benefit from a better understanding of the factors that underlie the production and the sharing of information. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: Many animals, including humans, acquire information through social learning. Although such information can be acquired easily, its potential unreliability means it should not be used indiscriminately. Cultural ‘transmission biases’ may allow individuals to weigh their reliance on social information according to a model''s characteristics. In one of the first studies to juxtapose two model-based biases, we investigated whether the age and knowledge state of a model affected the fidelity of children''s copying. Eighty-five 5-year-old children watched a video demonstration of either an adult or child, who had professed either knowledge or ignorance regarding a tool-use task, extracting a reward from that task using both causally relevant and irrelevant actions. Relevant actions were imitated faithfully by children regardless of the model''s characteristics, but children who observed an adult reproduced more irrelevant actions than those who observed a child. The professed knowledge state of the model showed a weaker effect on imitation of irrelevant actions. Overall, children favored the use of a ‘copy adults’ bias over a ‘copy task-knowledgeable individual’ bias, even though the latter could potentially have provided more reliable information. The use of such social learning strategies has significant implications for understanding the phenomenon of imitation of irrelevant actions (overimitation), instances of maladaptive information cascades, and cumulative culture. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: Individuals can use information gathered personally (individual information) or from others (social information) to track environmental change. Established mathematical models predict the rates of environmental change at which a social versus individual information gathering strategy would be adaptive, but the assumptions of these models, particularly the issue of individual flexibility in the strategy employed, have not been subject to rigorous empirical test. Participants (62 adult male and female humans) explored a virtual three-dimensional computer maze, with a forced choice between four reward locations. There were three low-value and one high-value reward, and monetary earnings were proportional to the total rewards located. The three experimental treatments were low, intermediate and high environmental variability, represented by the probability that the high-reward location moved between rounds. On the first 20 rounds, participants explored the maze alone. On the subsequent 80 rounds, participants could view a virtual player exploring the maze while exploring themselves. Participants exposed to the low environmental variability treatment tended to use social information, from the virtual player, more than players in the higher environmental variability treatments. These results are in line with the predictions of evolutionary models. Moreover, they suggest flexibility in information gathering strategies. Humans appear to assess current environmental variability and bias their reliance on social versus personal information accordingly. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

Abstract: 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. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]

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. [Copyright &y& Elsevier]

Abstract: 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 interindividual 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. [Copyright &y& Elsevier]