The evolution of teaching

Exploring new technologies for the future generation: exploration-exploitation trade-off in an intergenerational framework

Decision making on exploring or exploiting technology was studied by means of a laboratory experiment with a two-generation framework. In this framework, the design of a virtual tool is transmitted from the first to second generation, and hence, the former can help the latter by frequently exploring better tool designs but at the cost of reduced opportunities to exploit the existing tool to increase its own benefits. We set two experimental conditions ('repaid' and 'unrepaid') as well as a control condition (asocial), in which the second generation is absent. In the 'repaid' experimental condition, participants received an extra payment proportional to the score gained by the second generation, such that they were monetarily incentivized to help the second generation. Such an incentive was not given in the 'unrepaid' condition. An analysis of a formal model and computer simulations predicted that rational participants should increase investment in exploration only in the repaid condition when compared with the asocial control. The prediction was confirmed by the results of the experiment. These findings together suggest that humans may not have a propensity to invest in costly exploration of new technologies solely to help future generations.

Emergence of innovations in networked populations with reputation-driven interactions

In this work, we analyze how reputation-based interactions influence the emergence of innovations. To do so, we make use of a dynamic model that mimics the discovery process by which, at each time step, a pair of individuals meet and merge their knowledge to eventually result in a novel technology of higher value. The way in which these pairs are brought together is found to be crucial for achieving the highest technological level. Our results show that when the influence of reputation is weak or moderate, it induces an acceleration of the discovery process with respect to the neutral case (purely random coupling). However, an excess of reputation is clearly detrimental, because it leads to an excessive concentration of knowledge in a small set of people, which prevents a diversification of the technologies discovered and, in addition, leads to societies in which a majority of individuals lack technical capabilities.

Norm Dynamics: Interdisciplinary Perspectives on Social Norm Emergence, Persistence, and Change

Social norms are the glue that holds society together, yet our knowledge of them remains heavily intellectually siloed. This article provides an interdisciplinary review of the emerging field of norm dynamics by integrating research across the social sciences through a cultural-evolutionary lens. After reviewing key distinctions in theory and method, we discuss research on norm psychology-the neural and cognitive underpinnings of social norm learning and acquisition. We then overview how norms emerge and spread through intergenerational transmission, social networks, and group-level ecological and historical factors. Next, we discuss multilevel factors that lead norms to persist, change, or erode over time. We also consider cultural mismatches that can arise when a changing environment leads once-beneficial norms to become maladaptive. Finally, we discuss potential future research directions and the implications of norm dynamics for theory and policy.

Conditions under which faithful cultural transmission through teaching promotes cumulative cultural evolution

It has been argued that teaching promotes the accurate transmission of cultural traits and eventually leads to cumulative cultural evolution (CCE). However, previous studies have questioned this argument. In this study, we modified the action sequences model into a network exploring model with reinforcement learning to examine the conditions under which teaching promotes CCE. Our model incorporates a time trade-off between innovation and teaching. Simulations revealed that the positive influence of teaching on CCE depends on task difficulty. When the task was too difficult and advanced, such that it could not be accomplished through individual learning within a limited time, spending more time on teaching-even at the expense of time for innovation-contributed to CCE. On the contrary, the easier the task, the more time was spent on innovation than on teaching, which contributed to the improvement of performance. These findings suggest that teaching becomes more valuable as cultures become more complex. Therefore, humanity must have co-evolved a complex cumulative culture and teaching that supports cultural fidelity.

The cultural evolution of teaching

Teaching is an important process of cultural transmission. Some have argued that human teaching is a cognitive instinct - a form of 'natural cognition' centred on mindreading, shaped by genetic evolution for the education of juveniles, and with a normative developmental trajectory driven by the unfolding of a genetically inherited predisposition to teach. Here, we argue instead that human teaching is a culturally evolved trait that exhibits characteristics of a cognitive gadget. Children learn to teach by participating in teaching interactions with socialising agents, which shape their own teaching practices. This process hijacks psychological mechanisms involved in prosociality and a range of domain-general cognitive abilities, such as reinforcement learning and executive function, but not a suite of cognitive adaptations specifically for teaching. Four lines of evidence converge on this hypothesis. The first, based on psychological experiments in industrialised societies, indicates that domain-general cognitive processes are important for teaching. The second and third lines, based on naturalistic and experimental research in small-scale societies, indicate marked cross-cultural variation in mature teaching practice and in the ontogeny of teaching among children. The fourth line indicates that teaching has been subject to cumulative cultural evolution, i.e. the gradual accumulation of functional changes across generations.

Teaching strategies are shaped by experience with formal education: Experimental evidence from caregiver-child dyads in two Tannese communities

Humans are extraordinary in the extent to which we rely on cumulative culture to act upon and make sense of our environment. Teaching is one social learning process thought to be fundamental to the evolution of cumulative culture as a means of adaptation in our species. However, the frequency of teaching and how we teach are known to vary across human sociocultural contexts. Understanding this variation adds to our understanding of the complex interplay between cognition and culture in shaping learning behavior but also contributes to theory around the costs and benefits of different social learning processes. Here, we examined how prior experience with formal education is related to the frequency and diversity of teaching behaviors in an experimental paradigm where caregivers were motivated (but not instructed) to teach a simple skill to a child (7-10 years old). We identified and coded a suite of subtle nonverbal behaviors that could be construed as facilitating learning. Dyads (n = 64) were recruited from two communities on Tanna Island that differ in their experience with formal schooling and their acceptance of Western institutions. We found evidence for parallel teaching strategies in both communities. However, the rate and diversity of teaching behaviors were positively associated with caregiver's experience with formal schooling and independently and negatively associated with being from a village that rejects Western-derived institutions. These results further our understanding of how multiple cultural processes influence social learning and highlights the powerful influence of formal schooling on the cultural evolution of teaching in humans.

Four-Year-Olds Share General Knowledge and Use Generic Language When Teaching

Young children's receptiveness to teaching is unquestioned, but their understanding of pedagogy has only begun to be explored. Two experiments (N = 90; 45 female) with 4-year-olds from racially and ethnically diverse backgrounds were conducted to test if they exchange general information and use generic language when teaching. Children in both experiments taught more general than episodic information and used more generic than episodic language when teaching. Experiment 2 showed that children did not prefer to report general information or use generic language in a non-pedagogical context. The findings suggest that by 4 years old, children understand that the goal of teaching is to transmit general knowledge.

Costly teaching contributes to the acquisition of spear hunting skill among BaYaka forager adolescents

Teaching likely evolved in humans to facilitate the faithful transmission of complex tasks. As the oldest evidenced hunting technology, spear hunting requires acquiring several complex physical and cognitive competencies. In this study, we used observational and interview data collected among BaYaka foragers (Republic of the Congo) to test the predictions that costlier teaching types would be observed at a greater frequency than less costly teaching in the domain of spear hunting and that teachers would calibrate their teaching to pupil skill level. To observe naturalistic teaching during spear hunting, we invited teacher-pupil groupings to spear hunt while wearing GoPro cameras. We analysed 68 h of footage totalling 519 teaching episodes. Most observed teaching events were costly. Direct instruction was the most frequently observed teaching type. Older pupils received less teaching and more opportunities to lead the spear hunt than their younger counterparts. Teachers did not appear to adjust their teaching to pupil experience, potentially because age was a more easily accessible heuristic for pupil skill than experience. Our study shows that costly teaching is frequently used to transmit complex tasks and that instruction may play a privileged role in the transmission of spear hunting knowledge.

The origins of human cumulative culture: from the foraging niche to collective intelligence

Various studies have investigated cognitive mechanisms underlying culture in humans and other great apes. However, the adaptive reasons for the evolution of uniquely sophisticated cumulative culture in our species remain unclear. We propose that the cultural capabilities of humans are the evolutionary result of a stepwise transition from the ape-like lifestyle of earlier hominins to the foraging niche still observed in extant hunter-gatherers. Recent ethnographic, archaeological and genetic studies have provided compelling evidence that the components of the foraging niche (social egalitarianism, sexual and social division of labour, extensive co-residence and cooperation with unrelated individuals, multilocality, fluid sociality and high between-camp mobility) engendered a unique multilevel social structure where the cognitive mechanisms underlying cultural evolution (high-fidelity transmission, innovation, teaching, recombination, ratcheting) evolved as adaptations. Therefore, multilevel sociality underlies a 'social ratchet' or irreversible task specialization splitting the burden of cultural knowledge across individuals, which may explain why human collective intelligence is uniquely able to produce sophisticated cumulative culture. The foraging niche perspective may explain why a complex gene-culture dual inheritance system evolved uniquely in humans and interprets the cultural, morphological and genetic origins of Homo sapiens as a process of recombination of innovations appearing in differentiated but interconnected populations. This article is part of a discussion meeting issue 'The emergence of collective knowledge and cumulative culture in animals, humans and machines'.

A cognitive-evolutionary model for the evolution of teaching

Mechanisms for social learning have rightly been the focus of much work in cultural evolution. But mechanisms for teaching-mechanisms that determine what information is available for learners to learn in the first place-are equally important to cultural evolution, especially in the case of humans. Here, we propose a simple model of teaching in the context of skill transmission. Our model derives the evolutionary cost and benefit of teaching by explicitly representing cognitive aspects of skill transmission as a dual-inheritance process. We then show that teaching cannot evolve when its direct cost is too high. We also show that there is an "explain-exploit" trade-off inherent to teaching: when payoffs from sharing information are not constant, there can be an indirect cost to teaching. This gives rise to an opportunity cost that goes beyond any direct cost that it may also entail. Finally, we show that evolution limits the strength of teaching provided that the direct cost of teaching is an increasing function of teaching effort. We then discuss how these factors might explain why teaching mechanisms are self-limiting, suggesting that such mechanisms may nevertheless play an important role in the evolution of cumulative culture in humans.

Animal cognition in an urbanised world

Explaining how animals respond to an increasingly urbanised world is a major challenge for evolutionary biologists. Urban environments often present animals with novel problems that differ from those encountered in their evolutionary past. To navigate these rapidly changing habitats successfully, animals may need to adjust their behaviour flexibly over relatively short timescales. These behavioural changes, in turn, may be facilitated by an ability to acquire, store and process information from the environment. The question of how cognitive abilities allow animals to avoid threats and exploit resources (or constrain their ability to do so) is attracting increasing research interest, with a growing number of studies investigating cognitive and behavioural differences between urban-dwelling animals and their non-urban counterparts. In this review we consider why such differences might arise, focusing on the informational challenges faced by animals living in urban environments, and how different cognitive abilities can assist in overcoming these challenges. We focus largely on birds, as avian taxa have been the subject of most research to date, but discuss work in other species where relevant. We also address the potential consequences of cognitive variation at the individual and species level. For instance, do urban environments select for, or influence the development of, particular cognitive abilities? Are individuals or species with particular cognitive phenotypes more likely to become established in urban habitats? How do other factors, such as social behaviour and individual personality, interact with cognition to influence behaviour in urban environments? The aim of this review is to synthesise current knowledge and identify key avenues for future research, in order to improve our understanding of the ecological and evolutionary consequences of urbanisation.

The Life History of Learning Subsistence Skills among Hadza and BaYaka Foragers from Tanzania and the Republic of Congo

Aspects of human life history and cognition, such as our long childhoods and extensive use of teaching, theoretically evolved to facilitate the acquisition of complex tasks. The present paper empirically examines the relationship between subsistence task difficulty and age of acquisition, rates of teaching, and rates of oblique transmission among Hadza and BaYaka foragers from Tanzania and the Republic of Congo. We further examine cross-cultural variation in how and from whom learning occurred. Learning patterns and community perceptions of task difficulty were assessed through interviews. We found no relationship between task difficulty, age of acquisition, and oblique transmission, and a weak but positive relationship between task difficulty and rates of teaching. While same-sex transmission was normative in both societies, tasks ranked as more difficult were more likely to be transmitted by men among the BaYaka, but not among the Hadza, potentially reflecting cross-cultural differences in the sexual division of subsistence and teaching labor. Further, the BaYaka were more likely to report learning via teaching, and less likely to report learning via observation, than the Hadza, possibly owing to differences in socialization practices.

Evidence for Teaching in an Australian Songbird

Song in oscine birds (as in human speech and song) relies upon the rare capacity of vocal learning. Transmission can be vertical, horizontal, or oblique. As a rule, memorization and production by a naïve bird are not simultaneous: the long-term storage of song phrases precedes their first vocal rehearsal by months. While a wealth of detail regarding songbird enculturation has been uncovered by focusing on the apprentice, whether observational learning can fully account for the ontogeny of birdsong, or whether there could also be an element of active teaching involved, has remained an open question. Given the paucity of knowledge on animal cultures, I argue for the utility of an inclusive definition of teaching that encourages data be collected across a wide range of taxa. Borrowing insights from musicology, I introduce the Australian pied butcherbird (Cracticus nigrogularis) into the debate surrounding mechanisms of cultural transmission. I probe the relevance and utility of mentalistic, culture-based, and functionalist approaches to teaching in this species. Sonographic analysis of birdsong recordings and observational data (including photographs) of pied butcherbird behavior at one field site provide evidence that I assess based on criteria laid down by Caro and Hauser, along with later refinements to their functionalist definition. The candidate case of teaching reviewed here adds to a limited but growing body of reports supporting the notion that teaching may be more widespread than is currently realized. Nonetheless, I describe the challenges of confirming that learning has occurred in songbird pupils, given the delay between vocal instruction and production, as well as the low status accorded to anecdote and other observational evidence commonly mustered in instances of purported teaching. As a corrective, I press for an emphasis on biodiversity that will guide the study of teaching beyond human accounts and intractable discipline-specific burdens of proof.

Understanding Human Cognitive Uniqueness

Humanity has regarded itself as intellectually superior to other species for millennia, yet human cognitive uniqueness remains poorly understood. Here, we evaluate candidate traits plausibly underlying our distinctive cognition (including mental time travel, tool use, problem solving, social cognition, and communication) as well as domain generality, and we consider how human cognitive uniqueness may have evolved. We conclude that there are no traits present in humans and absent in other animals that in isolation explain our species' superior cognitive performance; rather, there are many cognitive domains in which humans possess unusually potent capabilities compared to those found in other species. Humans are flexible cognitive all-rounders, whose proficiency arises through interactions and reinforcement between cognitive domains at multiple scales.

The value of teaching increases with tool complexity in cumulative cultural evolution

Human cumulative cultural evolution (CCE) is recognized as a powerful ecological and evolutionary force, but its origins are poorly understood. The long-standing view that CCE requires specialized social learning processes such as teaching has recently come under question, and cannot explain why such processes evolved in the first place. An alternative, but largely untested, hypothesis is that these processes gradually coevolved with an increasing reliance on complex tools. To address this, we used large-scale transmission chain experiments (624 participants), to examine the role of different learning processes in generating cumulative improvements in two tool types of differing complexity. Both tool types increased in efficacy across experimental generations, but teaching only provided an advantage for the more complex tools. Moreover, while the simple tools tended to converge on a common design, the more complex tools maintained a diversity of designs. These findings indicate that the emergence of cumulative culture is not strictly dependent on, but may generate selection for, teaching. As reliance on increasingly complex tools grew, so too would selection for teaching, facilitating the increasingly open-ended evolution of cultural artefacts.

The value of teaching increases with tool complexity in cumulative cultural evolution

Human cumulative cultural evolution (CCE) is recognized as a powerful ecological and evolutionary force, but its origins are poorly understood. The long-standing view that CCE requires specialized social learning processes such as teaching has recently come under question, and cannot explain why such processes evolved in the first place. An alternative, but largely untested, hypothesis is that these processes gradually coevolved with an increasing reliance on complex tools. To address this, we used large-scale transmission chain experiments (624 participants), to examine the role of different learning processes in generating cumulative improvements in two tool types of differing complexity. Both tool types increased in efficacy across experimental generations, but teaching only provided an advantage for the more complex tools. Moreover, while the simple tools tended to converge on a common design, the more complex tools maintained a diversity of designs. These findings indicate that the emergence of cumulative culture is not strictly dependent on, but may generate selection for, teaching. As reliance on increasingly complex tools grew, so too would selection for teaching, facilitating the increasingly open-ended evolution of cultural artefacts.

The evolution of productive organizations

Organizations devoted to the production of goods and services, such as guilds, partnerships and modern corporations, have dominated the economic landscape in our species' history. We develop an explanation for their evolution drawing from cultural evolution theory. A basic tenet of this theory is that social learning, under certain conditions, allows for the diffusion of innovations in society and, therefore, the accumulation of culture. Our model shows that these organizations provide such conditions by possessing two characteristics, both prevalent in real world organizations: exclusivity of membership and more effective social learning within their boundaries. The model and its extensions parsimoniously explain the cooperative nature of the social learning advantage, organizational specialization, organizational rigidity and the locus of innovation. We find supportive evidence for our predictions using a sample of premodern societies drawn from the Ethnographic Atlas. Understanding the nature of these organizations informs the debate about their role in society.

Cultural adaptation is maximised when intelligent individuals rarely think for themselves

Humans are remarkable in their reliance on cultural inheritance, and the ecological success this has produced. Nonetheless, we lack a thorough understanding of how the cognitive underpinnings of cultural transmission affect cultural adaptation across diverse tasks. Here, we use an agent-based simulation to investigate how different learning mechanisms (both social and asocial) interact with task structure to affect cultural adaptation. Specifically, we compared learning through refinement, recombination or both, in tasks of different difficulty, with learners of different asocial intelligence. We find that for simple tasks all learning mechanisms are roughly equivalent. However, for hard tasks, performance was maximised when populations consisted of highly intelligent individuals who nonetheless rarely innovated and instead recombined existing information. Our results thus show that cumulative cultural adaptation relies on the combination of individual intelligence and 'blind' population-level processes, although the former may be rarely used. The counterintuitive requirement that individuals be highly intelligent, but rarely use this intelligence, may help resolve the debate over the role of individual intelligence in cultural adaptation.

The optimal timing of teaching and learning across the life course

The evolutionary biologist W. D. Hamilton (Hamilton 1966 J. Theor. Biol.12, 12-45. (doi:10.1016/0022-5193(66)90184-6)) famously showed that the force of natural selection declines with age, and reaches zero by the age of reproductive cessation. However, in social species, the transfer of fitness-enhancing resources by postreproductive adults increases the value of survival to late ages. While most research has focused on intergenerational food transfers in social animals, here we consider the potential fitness benefits of information transfer, and investigate the ecological contexts where pedagogy is likely to occur. Although the evolution of teaching is an important topic in behavioural biology and in studies of human cultural evolution, few formal models of teaching exist. Here, we present a modelling framework for predicting the timing of both information transfer and learning across the life course, and find that under a broad range of conditions, optimal patterns of information transfer in a skills-intensive ecology often involve postreproductive aged teachers. We explore several implications among human subsistence populations, evaluating the cost of hunting pedagogy and the relationship between activity skill complexity and the timing of pedagogy for several subsistence activities. Long lifespan and extended juvenility that characterize the human life history likely evolved in the context of a skills-intensive ecological niche with multi-stage pedagogy and multigenerational cooperation. This article is part of the theme issue 'Life history and learning: how childhood, caregiving and old age shape cognition and culture in humans and other animals'.

The role of food transfers in wild golden lion tamarins (Leontopithecus rosalia): Support for the informational and nutritional hypothesis

Callitrichidae is a unique primate family not only in terms of the large number of food transfers to infants but also for the prevalence of transfers that are initiated by the adults. It has been hypothesized that, as well as provisioning infants, callitrichid food transfers might function to teach the receiver what food types to eat. If food provisioning has a teaching function, we would expect successful food transfers to be more likely with food types that are novel to the juveniles. We would also expect juveniles to learn about foods from those transfers. We introduced different types of food (some familiar, some novel) to wild groups of golden lion tamarins (Leontopithecus rosalia). While novel foods were not more successfully transferred than familiar food in the experiment, transfers were more successful (i.e., the receiver obtained food) when the donor had previous experience with that food. Moreover, we found evidence suggesting that food transfers influenced the future foraging choices of juveniles. Our findings are consistent with the first and third criteria of the functional definition of teaching, which requires that tutors (the adults) modify their behavior in the presence of a naïve individual (a juvenile), and that the naïve individual learns from the modified behavior of the demonstrator. Our findings are also consistent with the provisioning function of food transfer. Social learning seems to play an important role in the development of young tamarins’ foraging preferences.

By Reverence, Not Fear: Prestige, Religion, and Autonomic Regulation in the Evolution of Cooperation

Recent evolutionary theories of religions emphasize their function as mechanisms for increasing prosociality. In particular, they claim that fear of supernatural punishment can be adaptive when it can compensate for humans' inability to monitor behavior and mete out punishment in large groups, as well when it can inhibit individuals' impulses for defection. Nonetheless, while fear of punishment may inhibit some anti-social behaviors like cheating, it is unlikely to motivate other prosocial behaviors, like helping. This is because human physiology has evolved separate neurological systems with differential behavioral correlates either for (1) processing fear and responding to threats or (2) facilitating social interactions in environments which are deemed safe. Almost all vertebrates possess autonomic pathways for processing threats and fear, which result in "fight," "flight," or "freeze" responses and so likely mediate interactions in dominance hierarchies. Mammals, however, possess an additional, phylogenetically newer, pathway dedicated to suppressing such defensive responses in the service of promoting social affiliation or engagement. Here, we argue that this mammalian physiology supports an alternative hierarchical system unique to humans: prestige. In contrast to dominance, which involves aversion, fear and shame, prestige hierarchies are characterized by physical proximity and eye-contact, as well as emotions like admiration and respect for leaders. Prestige also directs the flow of cultural information between individuals and has been argued to have evolved in order to help individuals acquire high quality information. Here, we argue that not only does the mammalian autonomic pathway support prestige hierarchies, but that coupled with prestige biased social learning, it opens up a means for prestigious figures, including deities, to support the spread of prosocial behaviors. Thus, in addition to theories that emphasizes religious fear as a motivating factor in the evolution of prosocial religions, we suggest that reverence - which includes awe and respect for, deference to, admiration of, and a desire to please a deity or supernatural agent - is likely just as important. In support of this, we identify cases of religions that appear to be defined predominantly by prestige dynamics, and not fear of supernatural punishment.

Animal learning as a source of developmental bias

As a form of adaptive plasticity that allows organisms to shift their phenotype toward the optimum, learning is inherently a source of developmental bias. Learning may be of particular significance to the evolutionary biology community because it allows animals to generate adaptively biased novel behavior tuned to the environment and, through social learning, to propagate behavioral traits to other individuals, also in an adaptively biased manner. We describe several types of developmental bias manifest in learning, including an adaptive bias, historical bias, origination bias, and transmission bias, stressing that these can influence evolutionary dynamics through generating nonrandom phenotypic variation and/or nonrandom environmental states. Theoretical models and empirical data have established that learning can impose direction on adaptive evolution, affect evolutionary rates (both speeding up and slowing down responses to selection under different conditions) and outcomes, influence the probability of populations reaching global optimum, and affect evolvability. Learning is characterized by highly specific, path-dependent interactions with the (social and physical) environment, often resulting in new phenotypic outcomes. Consequently, learning regularly introduces novelty into phenotype space. These considerations imply that learning may commonly generate plasticity first evolution.

Development of social learning and play in BaYaka hunter-gatherers of Congo

High-fidelity transmission of information through imitation and teaching has been proposed as necessary for cumulative cultural evolution. Yet, it is unclear when and for which knowledge domains children employ different social learning processes. This paper explores the development of social learning processes and play in BaYaka hunter-gatherer children by analysing video recordings and time budgets of children from early infancy to adolescence. From infancy to early childhood, hunter-gatherer children learn mainly by imitating and observing others’ activities. From early childhood, learning occurs mainly in playgroups and through practice. Throughout childhood boys engage in play more often than girls whereas girls start foraging wild plants from early childhood and spend more time in domestic activities and childcare. Sex differences in play reflect the emergence of sexual division of labour and the play-work transition occurring earlier for girls. Consistent with theoretical models, teaching occurs for skills/knowledge that cannot be transmitted with high fidelity through other social learning processes such as the acquisition of abstract information e.g. social norms. Whereas, observational and imitative learning occur for the transmission of visually transparent skills such as tool use, foraging, and cooking. These results suggest that coevolutionary relationships between human sociality, language and teaching have likely been fundamental in the emergence of human cumulative culture.

Assessor teaching and the development of the capacity to innovate and to imitate

Human beings have generated a system of cumulative cultural learning with great adaptive value. The evolution of this system required an increase in the capacity to innovate and to imitate in hominin lineage. However that development is costly and, moreover, imitation may restrain the adaptive advantage of a greater investment on innovation. We suggest that a possible way to overcome this problem in hominin evolution was parental teaching by evaluative feedback - i.e. assessor teaching. To explore this hypothesis we developed a mathematical model of cumulative cultural learning. We consider two cognitive levels, one Basic, with less ability to imitate and innovate, and the other Smart, with more ability of both. We study the transition from Basic to Smart in the absence or in presence of teaching. We also study the transition from no teaching to teaching at each cognitive level. We show that the transition to a Smart is easier in a teaching context than in one of only imitation. We also show that the transition to teaching is easier the greater the cognitive level.

Maternal influence on the development of nut-cracking skills in the chimpanzees of the Taï forest, Côte d'Ivoire (Pan troglodytes verus)

Chimpanzees' (Pan troglodytes) nut-cracking behavior represents one of the most complex forms of tool-use known among nonhuman animals. Given the close phylogenetic relationship between these apes and humans, investigating how such complex behavior develops in immatures can reveal the evolutionary roots of the cognitive processes that enabled the evolution of outstanding technological skills in our lineage. In this study, we investigated whether maternal behavior directly enhanced nut-cracking skills in immature individuals. We analyzed the behavior of 11 immatures and their mothers (N = 8) during nut-cracking activity, spanning over three consecutive nut-cracking seasons in the Taï National Park, Côte d'Ivoire. We used generalized linear mixed models to (a) obtain values of maternal scaffolding (defined as provision of learning opportunities) and active nut-sharing behavior of each mother according to the age of their offspring, and their average nut-cracking efficiency; (b) to test whether these variables enhanced immatures' nut-cracking skills; and (c) to test whether immatures' features (age, sex, and begging behavior) influenced maternal behavior as observed in our videos. Although the predicted values of maternal scaffolding and active nut-sharing did not obviously affect immatures' skills, they were positively influenced by the average maternal efficiency and by sharing hammers with their mothers. In addition, our observations showed that mothers were more likely to share nuts with their sons than with their daughters, and the more their offspring begged. Concurrently, male immatures were also found to beg more often than females. Our results add evidence on the ontogenetic pathway leading to the full acquisition of nut-cracking in wild chimpanzees and on the effect that maternal behavior can have in promoting the acquisition of this complex tool-use behavior. Moreover, our study strengthens the importance of naturalistic observations to understand complex skill acquisition. Finally, we suggest future avenues for investigating the maternal influence on learning.

Replication and emergence in cultural transmission

Humans are fundamentally defined by our socially transmitted, often long-lived, sophisticated cultural traits. The nature of cultural transmission is the subject of ongoing debate: while some emphasize that it is a biased, transformational process, others point out that high-fidelity transmission is required to explain the quintessentially cumulative nature of human culture. This paper integrates both views into a model that has two main components: First, actions - observable motor-behavioural patterns - are inherited with high fidelity, or replicated, when they are copied, largely independently of their normal, effective or conventional function, by naive learners. Replicative action copying is the unbiased transmission process that ensures the continuity of cultural traditions. Second, mental culture - knowledge, skills, attitudes and values - is not inherited directly or faithfully, but instead emerges, or develops, during usage, when individuals learn the associations between actions and their contexts and outcomes. Mental cultural traits remain stable over generations to the extent that they are informed by similar (replicated) motor patterns unfolding in similar environments. The arguments in support of this model rest on clear distinctions between inheritance and usage; between public-behavioural and private-mental culture; and between selection for fidelity and selection for function.

Food-Offering Calls in Wild Golden Lion Tamarins (Leontopithecus rosalia): Evidence for Teaching Behavior?

Many animals emit calls in the presence of food, but researchers do not always know the function of these calls. Evidence suggests that adult golden lion tamarins (Leontopithecus rosalia) use food-offering calls to teach juveniles which substrate (i.e., microhabitat) to forage on, or in, for food. However, we do not yet know whether juveniles learn from this aspect of the adults' behavior. Here we examine whether juveniles learn to associate food-offering calls with a foraging substrate, as a step toward assessing whether these calls qualify as teaching behavior. We compared the performance of four wild juvenile golden lion tamarins that were introduced to a novel substrate while exposed to playbacks of food-offering calls (experimental condition) to the performance of three juveniles that were exposed to the novel substrate without the presence of food-offering playbacks (control condition). We varied the location of the novel substrate between trials. We found that food-offering calls had an immediate effect on juveniles' interactions with the novel substrate, whether they inserted their hands into the substrate and their eating behavior, and a long-term effect on eating behavior at the substrate. The findings imply that juvenile golden lion tamarins can learn through food-offering calls about the availability of food at a substrate, which is consistent with (but does not prove) teaching in golden lion tamarins through stimulus enhancement. Our findings support the hypothesis that teaching might be more likely to evolve in cooperatively breeding species with complex ecological niches.

Autonomy, Equality, and Teaching among Aka Foragers and Ngandu Farmers of the Congo Basin

The significance of teaching to the evolution of human culture is under debate. We contribute to the discussion by using a quantitative, cross-cultural comparative approach to investigate the role of teaching in the lives of children in two small-scale societies: Aka foragers and Ngandu farmers of the Central African Republic. Focal follows with behavior coding were used to record social learning experiences of children aged 4 to 16 during daily life. "Teaching" was coded based on a functional definition from evolutionary biology. Frequencies, contexts, and subtypes of teaching as well as the identity of teachers were analyzed. Teaching was rare compared to observational learning, although both forms of social learning were negatively correlated with age. Children received teaching from a variety of individuals, and they also engaged in teaching. Several teaching types were observed, including instruction, negative feedback, and commands. Statistical differences in the distribution of teaching types and the identity of teachers corresponded with contrasting forager vs. farmer foundational cultural schema. For example, Aka children received less instruction, which empirically limits autonomous learning, and were as likely to receive instruction and negative feedback from other children as they were from adults. Commands, however, exhibited a different pattern suggesting a more complex role for this teaching type. Although consistent with claims that teaching is relatively rare in small-scale societies, this evidence supports the conclusion that teaching is a universal, early emerging cognitive ability in humans. However, culture (e.g., values for autonomy and egalitarianism) structures the nature of teaching.

The role of play objects and object play in human cognitive evolution and innovation

In this contribution, we address a major puzzle in the evolution of human material culture: If maturing individuals just learn their parental generation's material culture, then what is the origin of key innovations as documented in the archeological record? We approach this question by coupling a life‐history model of the costs and benefits of experimentation with a niche‐construction perspective. Niche‐construction theory suggests that the behavior of organisms and their modification of the world around them have important evolutionary ramifications by altering developmental settings and selection pressures. Part of Homo sapiens' niche is the active provisioning of children with play objects — sometimes functional miniatures of adult tools — and the encouragement of object play, such as playful knapping with stones. Our model suggests that salient material culture innovation may occur or be primed in a late childhood or adolescence sweet spot when cognitive and physical abilities are sufficiently mature but before the full onset of the concerns and costs associated with reproduction. We evaluate the model against a series of archeological cases and make suggestions for future research.

Teaching to make stone tools: new experimental evidence supporting a technological hypothesis for the origins of language

The relationship between lithic technology, learning and language is a topic of growing interest in human evolution studies, and has therefore been the subject of numerous scientific papers in recent years. To evaluate the role of language in the social transmission of lithic technology, we designed and developed an experimental protocol through which we compared the acquisition of knapping skills in thirty non-experts in the early stages of learning, by means of three mechanisms of social transmission: imitation-emulation, gestural communication, and verbal communication. All the apprentice knappers carried out the experimental task with blanks that were equal in shape and size, and were requested to replicate what the expert knapper was doing: the alternating method, a sufficiently simple, but systematic technique for detaching flakes from a core. We analysed each participant’s actions, including those of the master knapper, the final products (flakes and cores), and the knapping sequences, by analysing the refits. Our results show that the apprentices improved their knapping skills in teaching conditions -both gestural and verbal communication-, and specially through the latter. In conclusion, our study supports the hypothesis of co-evolution between lithic technology and social learning, which could have favoured the emergence of verbal language.

Ospreys do not teach offspring how to kill prey at the nest

There is strong evidence for teaching in only a handful of species, most of which are cooperative breeders, leading some researchers to suggest that teaching may be more likely to evolve in such species. Alternatively, this initial distribution could be an artefact of the popularity and tractability of cooperative breeders as behavioural study systems. Therefore, establishing or refuting this potential evolutionary link requires researchers to assess potential cases of teaching in more non-cooperatively breeding species. We tested for teaching in the osprey ( Pandion haliaetus ), a non-cooperatively-breeding bird anecdotally reported to teach hunting skills to their offspring. We tested whether parents brought back more live prey to the nest as their offspring got older, allowing the latter to practice killing prey in a manner analogous to the progressive teaching seen in meerkats. We found the opposite trend to that predicted by the teaching hypothesis, indicating that ospreys do not teach their young at the nest.

Cultural evolutionary theory: How culture evolves and why it matters

Human cultural traits-behaviors, ideas, and technologies that can be learned from other individuals-can exhibit complex patterns of transmission and evolution, and researchers have developed theoretical models, both verbal and mathematical, to facilitate our understanding of these patterns. Many of the first quantitative models of cultural evolution were modified from existing concepts in theoretical population genetics because cultural evolution has many parallels with, as well as clear differences from, genetic evolution. Furthermore, cultural and genetic evolution can interact with one another and influence both transmission and selection. This interaction requires theoretical treatments of gene-culture coevolution and dual inheritance, in addition to purely cultural evolution. In addition, cultural evolutionary theory is a natural component of studies in demography, human ecology, and many other disciplines. Here, we review the core concepts in cultural evolutionary theory as they pertain to the extension of biology through culture, focusing on cultural evolutionary applications in population genetics, ecology, and demography. For each of these disciplines, we review the theoretical literature and highlight relevant empirical studies. We also discuss the societal implications of the study of cultural evolution and of the interactions of humans with one another and with their environment.

Human Teaching and Cumulative Cultural Evolution

Although evidence of teaching behaviour has been identified in some nonhuman species, human teaching appears to be unique in terms of both the breadth of contexts within which it is observed, and in its responsiveness to needs of the learner. Similarly, cultural evolution is observable in other species, but human cultural evolution appears strikingly distinct. This has led to speculation that the evolutionary origins of these capacities may be causally linked. Here we provide an overview of contrasting perspectives on the relationship between teaching and cultural evolution in humans, and briefly review previous research which suggests that cumulative culture (here meaning cultural evolution featuring a trend towards improving functionality) can occur without teaching. We then report the results of a novel experimental study in which we investigated how the benefits of teaching may depend on the complexity of the skill to be acquired. Participants were asked to tie knots of varying complexity. In our Teaching condition, opportunities to interact with an experienced partner aided transmission of the most complex knots, but not simpler equivalents, relative to exposure to completed products alone (End State Only condition), and also relative to information about the process of completion (Intermediate States condition). We conclude by considering the plausibility of various accounts of the evolutionary relationship between teaching and cultural evolution in humans.

A Diverse and Flexible Teaching Toolkit Facilitates the Human Capacity for Cumulative Culture

Human culture is uniquely complex compared to other species. This complexity stems from the accumulation of culture over time through high- and low-fidelity transmission and innovation. One possible reason for why humans retain and create culture, is our ability to modulate teaching strategies in order to foster learning and innovation. We argue that teaching is more diverse, flexible, and complex in humans than in other species. This particular characteristic of human teaching rather than teaching itself is one of the reasons for human's incredible capacity for cumulative culture. That is, humans unlike other species can signal to learners whether the information they are teaching can or cannot be modified. As a result teaching in humans can be used to support high or low fidelity transmission, innovation, and ultimately, cumulative culture.

The origins of language in teaching

I introduce seven criteria for determining the validity of competing theories for the original function of language. I go on to present a novel explanation that meets all the criteria: language originally evolved to teach kin. I suggest that the use of symbols subsequently generated evolutionary feedback at two levels, in the form of self-modified selection pressures that favored structures in the mind that functioned to manipulate and use symbols with efficiency, and cultural selection on languages for learnability.

Cognition and Culture in Evolutionary Context

In humans and other animals, the individuals' ability to adapt efficiently and effectively to the niches they have actively contributed to construct relies heavily on an evolved psychology which has been shaped by biological, social, and cultural processes over evolutionary time. As expected, although many of the behavioral and cognitive components of this evolved psychology are widely shared across species, many others are species-unique. Although many animal species are known to acquire group-specific traditions (or cultures) via social learning, human culture is unique in terms of its contents and characteristics (observable and unobservable products, cumulative effects, norm conformity, and norm enforcement) and of its cognitive underpinnings (imitation, instructed teaching, and language). Here we provide a brief overview of some of the issues that are currently tackled in the field. We also highlight some of the strengths of a biological, comparative, non-anthropocentric and evolutionarily grounded approach to the study of culture. The main contributions of this approach to the science of culture are its emphasis (a) on the integration of information on mechanisms, function, and evolution, and on mechanistic factors located at different levels of the biological hierarchy, and (b) on the search for general principles that account for commonalities and differences between species, both in the cultural products and in the processes of innovation, dissemination, and accumulation involved that operate during developmental and evolutionary timespans.

The Foundations of Human Cooperation in Teaching and Imitation

Humans exhibit extensive large-scale cooperation, of a form unprecedented in the natural world. Here I suggest that this cooperation arises in our species alone because of our uniquely potent capacities for social learning, imitation and teaching, combined with the co-evolutionary feedbacks that these capabilities have generated on the human mind. Culture took human populations down evolutionary pathways not available to non-cultural species, either by creating conditions that promoted established cooperative mechanisms, such as indirect reciprocity and mutualism, or by generating novel cooperative mechanisms not seen in other taxa, such as cultural group selection. In the process, gene-culture co-evolution seemingly generated an evolved psychology, comprising an enhanced ability and motivation to learn, teach, communicate through language, imitate and emulate, as well as predispositions to docility, social tolerance, and the sharing of goals, intentions and attention. This evolved psychology is entirely different from that observed in any other animal, or that could have evolved through conventional selection on genes alone.

Innovation in the collective brain

Innovation is often assumed to be the work of a talented few, whose products are passed on to the masses. Here, we argue that innovations are instead an emergent property of our species' cultural learning abilities, applied within our societies and social networks. Our societies and social networks act as collective brains. We outline how many human brains, which evolved primarily for the acquisition of culture, together beget a collective brain. Within these collective brains, the three main sources of innovation are serendipity, recombination and incremental improvement. We argue that rates of innovation are heavily influenced by (i) sociality, (ii) transmission fidelity, and (iii) cultural variance. We discuss some of the forces that affect these factors. These factors can also shape each other. For example, we provide preliminary evidence that transmission efficiency is affected by sociality--languages with more speakers are more efficient. We argue that collective brains can make each of their constituent cultural brains more innovative. This perspective sheds light on traits, such as IQ, that have been implicated in innovation. A collective brain perspective can help us understand otherwise puzzling findings in the IQ literature, including group differences, heritability differences and the dramatic increase in IQ test scores over time.

How institutions shaped the last major evolutionary transition to large-scale human societies

What drove the transition from small-scale human societies centred on kinship and personal exchange, to large-scale societies comprising cooperation and division of labour among untold numbers of unrelated individuals? We propose that the unique human capacity to negotiate institutional rules that coordinate social actions was a key driver of this transition. By creating institutions, humans have been able to move from the default 'Hobbesian' rules of the 'game of life', determined by physical/environmental constraints, into self-created rules of social organization where cooperation can be individually advantageous even in large groups of unrelated individuals. Examples include rules of food sharing in hunter-gatherers, rules for the usage of irrigation systems in agriculturalists, property rights and systems for sharing reputation between mediaeval traders. Successful institutions create rules of interaction that are self-enforcing, providing direct benefits both to individuals that follow them, and to individuals that sanction rule breakers. Forming institutions requires shared intentionality, language and other cognitive abilities largely absent in other primates. We explain how cooperative breeding likely selected for these abilities early in the Homo lineage. This allowed anatomically modern humans to create institutions that transformed the self-reliance of our primate ancestors into the division of labour of large-scale human social organization.

Tool transfers are a form of teaching among chimpanzees

Teaching is a form of high-fidelity social learning that promotes human cumulative culture. Although recently documented in several nonhuman animals, teaching is rare among primates. In this study, we show that wild chimpanzees (Pan troglodytes troglodytes) in the Goualougo Triangle teach tool skills by providing learners with termite fishing probes. Tool donors experienced significant reductions in tool use and feeding, while tool recipients significantly increased their tool use and feeding after tool transfers. These transfers meet functional criteria for teaching: they occur in a learner’s presence, are costly to the teacher, and improve the learner’s performance. Donors also showed sophisticated cognitive strategies that effectively buffered them against potential costs. Teaching is predicted when less costly learning mechanisms are insufficient. Given that these chimpanzees manufacture sophisticated, brush-tipped fishing probes from specific raw materials, teaching in this population may relate to the complexity of these termite-gathering tasks.

Evolution of costly explicit memory and cumulative culture

Humans can acquire new information and modify it (cumulative culture) based on their learning and memory abilities, especially explicit memory, through the processes of encoding, consolidation, storage, and retrieval. Explicit memory is categorized into semantic and episodic memories. Animals have semantic memory, while episodic memory is unique to humans and essential for innovation and the evolution of culture. As both episodic and semantic memory are needed for innovation, the evolution of explicit memory influences the evolution of culture. However, previous theoretical studies have shown that environmental fluctuations influence the evolution of imitation (social learning) and innovation (individual learning) and assume that memory is not an evolutionary trait. If individuals can store and retrieve acquired information properly, they can modify it and innovate new information. Therefore, being able to store and retrieve information is essential from the perspective of cultural evolution. However, if both storage and retrieval were too costly, forgetting and relearning would have an advantage over storing and retrieving acquired information. In this study, using mathematical analysis and individual-based simulations, we investigate whether cumulative culture can promote the coevolution of costly memory and social and individual learning, assuming that cumulative culture improves the fitness of each individual. The conclusions are: (1) without cumulative culture, a social learning cost is essential for the evolution of storage-retrieval. Costly storage-retrieval can evolve with individual learning but costly social learning does not evolve. When low-cost social learning evolves, the repetition of forgetting and learning is favored more than the evolution of costly storage-retrieval, even though a cultural trait improves the fitness. (2) When cumulative culture exists and improves fitness, storage-retrieval can evolve with social and/or individual learning, which is not influenced by the degree of the social learning cost. Whether individuals socially learn a low level of culture from observing a high or the low level of culture influences the evolution of memory and learning, especially individual learning.