The evolution of cultural adaptations: Fijian food taboos protect against dangerous marine toxins

The application of evolutionary theory to understanding the origins of our species'' capacities for social learning has generated key insights into cultural evolution. By focusing on how our psychology has evolved to adaptively extract beliefs and practices by observing others, theorists have hypothesized how social learning can, over generations, give rise to culturally evolved adaptations. While much field research documents the subtle ways in which culturally transmitted beliefs and practices adapt people to their local environments, and much experimental work reveals the predicted patterns of social learning, little research connects real-world adaptive cultural traits to the patterns of transmission predicted by these theories. Addressing this gap, we show how food taboos for pregnant and lactating women in Fiji selectively target the most toxic marine species, effectively reducing a woman''s chances of fish poisoning by 30 per cent during pregnancy and 60 per cent during breastfeeding. We further analyse how these taboos are transmitted, showing support for cultural evolutionary models that combine familial transmission with selective learning from locally prestigious individuals. In addition, we explore how particular aspects of human cognitive processes increase the frequency of some non-adaptive taboos. This case demonstrates how evolutionary theory can be deployed to explain both adaptive and non-adaptive behavioural patterns.     

The Big Man Mechanism: how prestige fosters cooperation and creates prosocial leaders

Anthropological evidence from diverse societies suggests that prestige-based leadership may provide a foundation for cooperation in many contexts. Here, inspired by such ethnographic observations and building on a foundation of existing research on the evolution of prestige, we develop a set of formal models to explore when an evolved prestige psychology might drive the cultural evolution of n-person cooperation, and how such a cultural evolutionary process might create novel selection pressures for genes that make prestigious individuals more prosocial. Our results reveal (i) how prestige can foster the cultural emergence of cooperation by generating correlated behavioural phenotypes, both between leaders and followers, and among followers; (ii) why, in the wake of cultural evolution, natural selection favours genes that make prestigious leaders more prosocial, but only when groups are relatively small; and (iii), why the effectiveness of status differences in generating cooperation in large groups depends on cultural transmission (and not primarily on deference or coercion). Our theoretical framework, and the specific predictions made by these models, sketch out an interdisciplinary research programme that cross-cuts anthropology, biology, psychology and economics. Some of our predictions find support from laboratory work in behavioural economics and are consistent with several real-world patterns.     

The cultural evolution of fertility decline

Cultural evolutionists have long been interested in the problem of why fertility declines as populations develop. By outlining plausible mechanistic links between individual decision-making, information flow in populations and competition between groups, models of cultural evolution offer a novel and powerful approach for integrating multiple levels of explanation of fertility transitions. However, only a modest number of models have been published. Their assumptions often differ from those in other evolutionary approaches to social behaviour, but their empirical predictions are often similar. Here I offer the first overview of cultural evolutionary research on demographic transition, critically compare it with approaches taken by other evolutionary researchers, identify gaps and overlaps, and highlight parallel debates in demography. I suggest that researchers divide their labour between three distinct phases of fertility decline—the origin, spread and maintenance of low fertility—each of which may be driven by different causal processes, at different scales, requiring different theoretical and empirical tools. A comparative, multi-level and mechanistic framework is essential for elucidating both the evolved aspects of our psychology that govern reproductive decision-making, and the social, ecological and cultural contingencies that precipitate and sustain fertility decline.     

Direct reciprocity under uncertainty does not explain one-shot cooperation,but demonstrates the benefits of a norm psychology

Humans in many societies cooperate in economic experiments at much higher levels than would be expected if their goal was maximizing economic returns, even when their interactions are anonymous and one-shot. This is a puzzle because paying a cost to benefit another in one-shot interactions gives no direct or indirect benefits to the cooperator. This paper explores the logic of two competing evolutionary hypotheses to explain this behavior. The ``norm psychology'' hypothesis holds that a player's choice of strategy reflects socially-learned cultural norms. Its premise is that over the course of human evolutionary history, cultural norms varied considerably across human societies, and through a process of gene-culture co-evolution, humans evolved mechanisms to learn and adopt the norms that are successful in their particular society. The ``mismatch'' hypothesis holds that pro-social preferences evolved genetically in our hunter–gatherer past where one-shot anonymous interactions were rare and these preferences are misapplied in modern laboratory settings. I compare these hypotheses by adopting a well-known model of the mismatch hypothesis and show that selection for one-shot cooperation in the model is an artifact of agents being confined to only two strategies: Tit-for-Tat and Always Defect. Allowing for repentant and forgiving strategies reverses selection away from one-shot cooperation under all environmental parameters. Direct reciprocity does not necessarily lead to cooperation, but instead generates many different normative equilibria depending on a group's idiosyncratic evolutionary history. Therefore, an agent whose behavior is evoked solely from non-cultural environmental cues will be disadvantaged relative to an agent who learns the locally successful norms. Cooperation in one-shot laboratory experiments is thus more easily explained as the result of a psychology evolved for learning social norms than as a genetic mismatch.     

The Phylogeny of Little Red Riding Hood

Researchers have long been fascinated by the strong continuities evident in the oral traditions associated with different cultures. According to the ‘historic-geographic’ school, it is possible to classify similar tales into “international types” and trace them back to their original archetypes. However, critics argue that folktale traditions are fundamentally fluid, and that most international types are artificial constructs. Here, these issues are addressed using phylogenetic methods that were originally developed to reconstruct evolutionary relationships among biological species, and which have been recently applied to a range of cultural phenomena. The study focuses on one of the most debated international types in the literature: ATU 333, ‘Little Red Riding Hood’. A number of variants of ATU 333 have been recorded in European oral traditions, and it has been suggested that the group may include tales from other regions, including Africa and East Asia. However, in many of these cases, it is difficult to differentiate ATU 333 from another widespread international folktale, ATU 123, ‘The Wolf and the Kids’. To shed more light on these relationships, data on 58 folktales were analysed using cladistic, Bayesian and phylogenetic network-based methods. The results demonstrate that, contrary to the claims made by critics of the historic-geographic approach, it is possible to identify ATU 333 and ATU 123 as distinct international types. They further suggest that most of the African tales can be classified as variants of ATU 123, while the East Asian tales probably evolved by blending together elements of both ATU 333 and ATU 123. These findings demonstrate that phylogenetic methods provide a powerful set of tools for testing hypotheses about cross-cultural relationships among folktales, and point towards exciting new directions for research into the transmission and evolution of oral narratives.     

The origins of music in auditory scene analysis and the roles of evolution and culture in musical creation

Whether music was an evolutionary adaptation that conferred survival advantages or a cultural creation has generated much debate. Consistent with an evolutionary hypothesis, music is unique to humans, emerges early in development and is universal across societies. However, the adaptive benefit of music is far from obvious. Music is highly flexible, generative and changes rapidly over time, consistent with a cultural creation hypothesis. In this paper, it is proposed that much of musical pitch and timing structure adapted to preexisting features of auditory processing that evolved for auditory scene analysis (ASA). Thus, music may have emerged initially as a cultural creation made possible by preexisting adaptations for ASA. However, some aspects of music, such as its emotional and social power, may have subsequently proved beneficial for survival and led to adaptations that enhanced musical behaviour. Ontogenetic and phylogenetic evidence is considered in this regard. In particular, enhanced auditory–motor pathways in humans that enable movement entrainment to music and consequent increases in social cohesion, and pathways enabling music to affect reward centres in the brain should be investigated as possible musical adaptations. It is concluded that the origins of music are complex and probably involved exaptation, cultural creation and evolutionary adaptation.     

Culture, embodiment and genes: unravelling the triple helix

Much recent work stresses the role of embodiment and action in thought and reason, and celebrates the power of transmitted cultural and environmental structures to transform the problem-solving activity required of individual brains. By apparent contrast, much work in evolutionary psychology has stressed the selective fit of the biological brain to an ancestral environment of evolutionary adaptedness, with an attendant stress upon the limitations and cognitive biases that result. On the face of it, this suggests either a tension or, at least, a mismatch, with the symbiotic dyad of cultural evolution and embodied cognition. In what follows, we explore this mismatch by focusing on three key ideas: cognitive niche construction; cognitive modularity; and the existence (or otherwise) of an evolved universal human nature. An appreciation of the power and scope of the first, combined with consequently more nuanced visions of the latter two, allow us to begin to glimpse a much richer vision of the combined interactive potency of biological and cultural evolution for active, embodied agents.     

Studying Cultural Evolution at the Tips: Human Cross-cultural Ecology

While human genetic variation is limited due to a bottleneck on the origin of the species ～200 kya, cultural traits can change more rapidly, and may do so in response to the variation in human habitats. Does cultural diversification simulate a natural experiment in evolution much like biodiversity so that cultural divergences and convergences can be interpreted in terms of the differences and similarities of local environments? Or is cultural diversity simply the result of human behavioral flexibility? Although the majority of cultural data comes from the tips of the hominin phylogeny, anthropologists can follow the example of evolutionary ecologists, who often compare the endpoints of phylogenies when that is all that is available. This article compares 97 contemporary indigenous language communities from around the world, and 24 of their cultural traditions, to help determine whether human cultures and their cultural traits are proportionately dispersed, as predicted by the neutral theory of biodiversity, or whether they show non-proportionalities that could be explained with evolutionary reasoning.     

Culture and the evolution of human cooperation

The scale of human cooperation is an evolutionary puzzle. All of the available evidence suggests that the societies of our Pliocene ancestors were like those of other social primates, and this means that human psychology has changed in ways that support larger, more cooperative societies that characterize modern humans. In this paper, we argue that cultural adaptation is a key factor in these changes. Over the last million years or so, people evolved the ability to learn from each other, creating the possibility of cumulative, cultural evolution. Rapid cultural adaptation also leads to persistent differences between local social groups, and then competition between groups leads to the spread of behaviours that enhance their competitive ability. Then, in such culturally evolved cooperative social environments, natural selection within groups favoured genes that gave rise to new, more pro-social motives. Moral systems enforced by systems of sanctions and rewards increased the reproductive success of individuals who functioned well in such environments, and this in turn led to the evolution of other regarding motives like empathy and social emotions like shame.     

Investigation of some medicinal plants traditionally used for treatment of malaria in Kenya as potential sources of antimalarial drugs

Malaria is a major public health problem in many tropical and subtropical countries and the burden of this disease is getting worse, mainly due to the increasing resistance of Plasmodium falciparum against the widely available antimalarial drugs. There is an urgent need for discovery of new antimalarial agents. Herbal medicines for the treatment of various diseases including malaria are an important part of the cultural diversity and traditions of which Kenya′s biodiversity has been an integral part. Two major antimalarial drugs widely used today came originally from indigenous medical systems, that is quinine and artemisinin, from Peruvian and Chinese ancestral treatments, respectively. Thus ethnopharmacology is a very important resource in which new therapies may be discovered. The present review is an analysis of ethnopharmacological publications on antimalarial therapies from some Kenyan medicinal plants.     

The dilemma posed by minority medical traditions in pluralistic societies: The case of China and Canada

Pluralistic societies such as China and Canada frequently find themselves pursuing potentially contradictory goals. China's contradiction results from a desire to preserve cultural diversity while eliminating ‘backward tendencies’ which work against the economic and social development of the country as a whole. Canada's contradiction results from a desire to preserve cultural diversity while maintaining an emphasis upon equality of rights and responsibilities for all Canadians. Behind these differences in ideology, however, is a more basic structural contradiction ‐ namely, that cultural pluralism, while considered an asset as long as it is restricted to preserving unique cultural traditions, is nevertheless a threat to a strong central government if interpreted to imply the power to set policy at the local level. To explore this issue, this article compares China and Canada in terms of three related topics. First, it briefly examines the multicultural policy of China and Canada. This is followed by a discussion of medical pluralism in China and Canada, with an emphasis upon the health of minority groups and the status of minority healing traditions. Finally, common perceptions of shamanic healing traditions in both China and Canada are considered. It is in relation to shamanism that the dilemma posed by cultural pluralism is most clearly delimited.     

Evolutionary accounts of human behavioural diversity

Human beings persist in an extraordinary range of ecological settings, in the process exhibiting enormous behavioural diversity, both within and between populations. People vary in their social, mating and parental behaviour and have diverse and elaborate beliefs, traditions, norms and institutions. The aim of this theme issue is to ask whether, and how, evolutionary theory can help us to understand this diversity. In this introductory article, we provide a background to the debate surrounding how best to understand behavioural diversity using evolutionary models of human behaviour. In particular, we examine how diversity has been viewed by the main subdisciplines within the human evolutionary behavioural sciences, focusing in particular on the human behavioural ecology, evolutionary psychology and cultural evolution approaches. In addition to differences in focus and methodology, these subdisciplines have traditionally varied in the emphasis placed on human universals, ecological factors and socially learned behaviour, and on how they have addressed the issue of genetic variation. We reaffirm that evolutionary theory provides an essential framework for understanding behavioural diversity within and between human populations, but argue that greater integration between the subfields is critical to developing a satisfactory understanding of diversity.     

The adaptive legacy of human evolution: A search for the environment of evolutionary adaptedness

The growth of evolutionary psychology has led to renewed interest in what might be the significant evolutionary heritage of people living today, and in the extent to which humans are suited to a particular adaptive environment—the EEA. The EEA, though, is a new tool in the battery of evolutionary concepts, and it is important both that it is scrutinized for its utility, and that the actual reconstructions of the environments in which humans and hominids evolved are based on sound palaeobiological inference and an appropriate use of the phylogenetic context of primate evolution.     

Physically strong men are more militant: A test across four countries

There is substantial evidence from archaeology, anthropology, primatology, and psychology indicating that humans have a long evolutionary history of war. Natural selection, therefore, should have designed mental adaptations for making decisions about war. These adaptations evolved in past environments, and so they may respond to variables that were ancestrally relevant but not relevant in modern war. For example, ancestrally in small-scale combat, a skilled fighter would be more likely to survive a war and bring his side to victory. This ancestral regularity would have left its mark on modern men's intergroup psychology: more formidable men should still be more supportive of war. We test this hypothesis in four countries: Argentina, Denmark, Israel, and Romania. In three, physically strong men (but not strong women) were significantly more supportive of military action. These findings support the hypothesis that modern warfare is influenced by a psychology designed for ancestral war.     

Mode and tempo in the evolution of socio-political organization: reconciling 'Darwinian' and 'Spencerian' evolutionary approaches in anthropology

Traditional investigations of the evolution of human social and political institutions trace their ancestry back to nineteenth century social scientists such as Herbert Spencer, and have concentrated on the increase in socio-political complexity over time. More recent studies of cultural evolution have been explicitly informed by Darwinian evolutionary theory and focus on the transmission of cultural traits between individuals. These two approaches to investigating cultural change are often seen as incompatible. However, we argue that many of the defining features and assumptions of 'Spencerian' cultural evolutionary theory represent testable hypotheses that can and should be tackled within a broader 'Darwinian' framework. In this paper we apply phylogenetic comparative techniques to data from Austronesian-speaking societies of Island South-East Asia and the Pacific to test hypotheses about the mode and tempo of human socio-political evolution. We find support for three ideas often associated with Spencerian cultural evolutionary theory: (i) political organization has evolved through a regular sequence of forms, (ii) increases in hierarchical political complexity have been more common than decreases, and (iii) political organization has co-evolved with the wider presence of hereditary social stratification.     

A Comparative Analysis of Nineteenth Century Pharmacopoeias in the Southern United States: A Case Study Based on the Gideon Lincecum Herbarium<Superscript>1</Superscript>

A Comparative Analysis of Nineteenth Century Pharmacopoeias in the Southern United States: A Case Study Based on the Gideon Lincecum Herbarium. The Gideon Lincecum Herbarium represents the pharmacopoeia of Dr. Gideon Lincecum, a botanical physician practicing in Mississippi and Texas during the first half of the nineteenth century. The herbarium contains 313 specimens representing 309 species, 242 genera, and 96 families, and includes ethnobotanical annotations for 286 medicinal taxa. The collection data provided by Lincecum indicate that the specimens were collected between 1835 and 1852. With the exception of 22 specimens considered by Campbell (1951), this is the first study to place this pharmacopoeia in a historical context. Taxonomic determinations of the herbarium specimens were confirmed or corrected. Comparative analyses were conducted to investigate the relationship of Lincecum’s pharmacopoeia to those of six other medical traditions practiced in the southern United States during the nineteenth century. Cluster analyses based on Jaccard co-efficient placed the historical pharmacopoeias of medical traditions in the early nineteenth century into distinct Euro–American and American Indian groups. Despite the recognition of distinct allopathic and botanical medical traditions, an extensive overlap in the composition of their pharmacopoeias is observed. This may reflect the reliance of these traditions on allopathic principles and drugs of plant origin during the first half of the nineteenth century. In contrast, Cherokee, Chickasaw, Choctaw, and Creek pharmacopoeias show limited overlap with each other in composition despite a long history of interaction between these groups. Lincecum’s pharmacopoeia shares a larger Jaccard co–efficient value with the Choctaw pharmacopoeia than would be expected based on their placement in distinct Euro–American and American Indian groups in the dendrogram. The large proportion of Lincecum’s citations that reference Choctaw informants provides direct evidence for the incorporation of Choctaw medical knowledge and taxa into Lincecum’s pharmacopoeia. These data suggest that the composition of historical pharmacopoeias is influenced by both contemporary medical practices and the regional and cultural contexts in which the pharmacopoeias are utilized.     

Cognitive Tracks of Cultural Inheritance: How Evolved Intuitive Ontology Governs Cultural Transmission

"Acquired culture" depends on social transmission and displays salient cross-cultural variability. It seems unconnected to adaptive fitness. It is, however, constrained by evolved properties of the mind. Recurrent—not necessarily universal—features of acquired culture can be explained by taking into account the early development and constraining power of intuitive ontology , a set of principled domain-specific inferential capacities. These allow us to predict recurrent trends in domains as diverse as folk-psychology, representations of natural kinds, the uses of literacy, the acquisition of scientific beliefs, and even the limiting-case of religious ontologies. In all these domains the notion of cultural transmission along domainspecific cognitive tracks governed by intuitive ontology is supported by independent psychological evidence and provides testable explanations for recurrent features in the anthropological record, [ evolution, culture, cultural universal, cognitive development, evolutionary psychology ]     

Evolutionary psychology and the generation of culture,part I: Theoretical considerations

Culture is the ongoing product of the evolved psyches of individual humans living in groups. Progress in our understanding of culture as a phenomenon depends on progress in uncovering the nature of the evolved mechanisms that comprise the human psyche, including but not limited to those responsible for learning. Actual attemps to specify information processing mechanisms that could, in fact, perform tasks humans routinely perform have demonstrated that the human psyche cannot, even in principle, be comprised only of a general purpose learning mechanism or any other general purpose mechanism, such as an inclusive fitness maximizer. Instead, the human psyche appears to consist of a large number of mechanisms, many or most of which are special purpose and domain-specific. The output of these mechanisms taken together constitutes the “private culture” of each individual, and the interactions of these private cultures lead to the cross-individual patterns of similarity that have led anthropologists to think typologically of social groups as having “a” culture. The construction of a scientific theory of culture requires as its building blocks specific models of these psychological mechanisms, and so evolutionary anthropology depends on the forging of an evolutionary psychology. The most productive application of evolutionary biology is, therefore, in the study of the psychological mechanisms that generate and shape culture, rather than in the attempt to impose on cultural change too close a parallel to population genetics and organic evolution.     

How cooperation became the norm

Most of the contributions to Cooperation and Its Evolution grapple with the distinctive challenges presented by the project of explaining human sociality. Many of these puzzles have a ‘chicken and egg’ character: our virtually unparalleled capacity for large-scale cooperation is the product of psychological, behavioural, and demographic changes in our recent evolutionary history, and these changes are linked by complex patterns of reciprocal dependence. There is much we do not yet understand about the timing of these changes, and about the order in which different aspects of human social psychology (co-)evolved. In this review essay, I discuss four such puzzles the volume raises. These concern punishment and norm-psychology, moral judgement and the moral emotions, hierarchy and top-down coercion, and property rights and legal systems.     

The use and abuse of Darwinian psychology: Its impact on attempts to determine the evolutionary basis of human rape

This paper evaluates the impact of the recent theoretical shift to Darwinian psychology on attempts to determine the evolutionary basis of human rape. The first step in this evaluation is a summary of the debate over whether human rape is an adaptation or a by-product of other evolved differences between men and women as it was presented in a pre-Darwinian psychological framework. These early evolutionary explanations are then contrasted with more recent works addressing the same issue from the perspective of Darwinian psychology. It is concluded that while the new approach may have helped generate new predictions, it has also led to the unwarranted exclusion of relevant data, led to questionable interpretations of new types of data, introduced ambiguous jargon, and potentially jeopardized the testability of certain evolutionary explanations. The root of most of these problems is suggested to exist, not in the principles of Darwinian psychology, but in the exaggeration of the differences between Darwinian psychology and earlier evolutionary approaches.