Charles Efferson

• Professor at University of Lausanne

Results from cultural evolutionary theory often suggest that social learning can lead cultural groups to differ markedly in the same environment. Put differently, cultural evolutionary processes can in principle stabilise behavioural differences between groups, which in turn could lead selection pressures to vary across cultural groups. Separating...

A basic hypothesis is that cultural evolutionary processes sustain differences between groups, these differences have evolutionary relevance, and they would not otherwise occur in a system without cultural transmission. The empirical challenge is that groups vary for many reasons, and isolating the causal effects of culture often requires appropria...

Repeated interactions provide an evolutionary explanation for one-shot human cooperation that is counterintuitive but orthodox1–3. Intergroup competition4–7 provides an explanation that is intuitive but heterodox. Here, using models and a behavioural experiment, we show that neither mechanism reliably supports cooperation. Ambiguous reciprocity, a...

Applied cultural evolution includes any effort to mobilize social learning and cultural evolution to promote behaviour change. Social tipping is one version of this idea based on conformity and coordination. Conformity and coordination can reinforce a harmful social norm, but they can also accelerate change from a harmful norm to a beneficial alter...

Causal inference lies at the core of many scientific endeavours. Yet, answering causal questions is challenging, especially when studying culture as a causal force. Against this backdrop, this paper reviews research designs and statistical tools that can be used—together with strong theory and knowledge about the context of study—to identify the ca...

Humans have evolved culturally and perhaps genetically to be unsustainable. We exhibit a deep and consistent pattern of short-term resource exploitation behaviours and institutions. We distinguish agentic and naturally selective forces in cultural evolution. Agentic forces are quite important compared to the blind forces (random variation and natur...

We derive and analyse a model with unusual features characterizing human activities over the long-run. First, human population dynamics draw heavily on consumer–resource modelling in ecology in that humans must consume biological resources to produce new humans. Second, the model also draws heavily from economic growth theory in that humans do not...

Discussions of the environmental impact that revolve around monetary incentives and other easy-to-measure factors are important, but they neglect culture. Pro-environmental values will be crucial when facing sustainability challenges in the Anthropocene, and demand among green consumers is arguably critical to incentivise sustainable production. Ho...

This handbook is currently in development, with individual articles publishing online in advance of print publication. At this time, we cannot add information about unpublished articles in this handbook, however the table of contents will continue to grow as additional articles pass through the review process and are added to the site. Please note...

Rapid and comprehensive social change is required to mitigate pressing environmental issues such as climate change. Social tipping interventions have been proposed as a policy tool for creating this kind of change. Social tipping means that a small minority committed to a target behaviour can create a self-reinforcing dynamic, which establishes the...

Social tipping can accelerate behaviour change consistent with policy objectives in diverse domains from social justice to climate change. Hypothetically, however, group identities might undermine tipping in ways that policymakers do not anticipate. To examine this, we implemented an experiment around the 2020 US federal elections. The participants...

Models of frequency-dependent social learning posit that individuals respond to the commonality of behaviours without additional variables modifying this. Such strategies bring important trade-offs e.g., conformity is beneficial when observing people facing the same task but harmful when observing those facing a different task. Instead of rigidly r...

Many social exchanges produce benefits that would not exist otherwise, but anticipating conflicts about how to distribute these benefits can derail exchange and destroy the gains. Coordination norms can solve this problem by providing a shared understanding of how to distribute benefits, but such norms can also perpetuate group-level inequality. To...

Public health policy often involves implementing cost-efficient, large-scale interventions. When mandating or forbidding a specific behaviour is not permissible, public health professionals may draw on behaviour change interventions to achieve socially beneficial policy objectives. Interventions can have two main effects: (i) a direct effect on peo...

Sex ratios at birth favoring boys are being documented in a growing number of countries, a pattern indicating that families selectively abort females. Son bias also explains why, in many countries, girls have more siblings and are born at relatively earlier parities compared with their brothers. In this study, we develop novel methods for measuring...

The popular practice of “leading by the successful” is viewed as a hallmark of motivational leadership. A central rationale for leaders to make successful team members salient is that it may induce social learning, where followers strive to adopt a favorable behavior. The reliance of a leader on such success-biased social learning presumes that imi...

False beliefs can spread within societies even when they are costly and when individuals share access to the same objective reality. Research on the cultural evolution of misbeliefs has demonstrated that a social context can explain what people think, but not whether it also explains how people think. We shift the focus from the diffusion of false...

False beliefs can spread within societies even when they are costly and when individuals share access to the same objective reality. Research on the cultural evolution of misbeliefs has demonstrated that a social context can explain what people think but not whether it also explains how people think. We shift the focus from the diffusion of false b...

Why do people sometimes hold unjustifed beliefs and make harmful choices? Three hypotheses include (i) contemporary incentives in which some errors cost more than oth- ers, (ii) cognitive biases evolved to manage ancestral incentives with variation in error costs, and (iii) social learning based on choice frequencies. With both modelling and a beha...

For a policy-maker promoting the end of a harmful tradition, conformist social influence is a compelling mechanism. If an intervention convinces enough people to abandon the tradition, this can spill over and induce others to follow. A key objective is thus to activate such spillovers and amplify an intervention’s effects. With female genital cutti...

Preliminary report on study of son bias in Armenia

Corruption in the education sector is pervasive in many (developing) countries. We examine two interventions to fight corruption in education. The first is an increase of the fixed-wage of teachers. The second is the introduction of a piece-rate scheme that rewards teachers according to the number of students that they attract. We model these mecha...

Corruption in the education sector is pervasive in many (developing) countries. We examine two interventions to fight corruption in education. The first is an increase of the fixed-wage of teachers. The second is the introduction of a piece-rate scheme that rewards teachers according to the number of students that they attract. We model these mecha...

Economic psychology refers to the psychological processes that affect economic decision making. The study of economic psychology has become increasingly interdisciplinary in recent years, with growing influence in economics, anthropology, and other social sciences. A rise in the use of behavioral experiments, in particular, has led researchers to r...

The importance of culture for human social evolution hinges largely on the extent to which culture supports outcomes that would not otherwise occur. An especially controversial claim is that social learning leads groups to coalesce around group-typical behaviours and associated social norms that spill over to shape choices in asocial settings. To t...

The evolution of cooperation is a frequently debated topic. A study assessing scenarios in which people judge each other shows that a simple moral rule suffices to drive the evolution of cooperation.

We propose to change the default P-value threshold for statistical significance for claims of new discoveries from 0.05 to 0.005.

"We propose to change the default P-value threshold forstatistical significance for claims of new discoveries from 0.05 to 0.005."

Worldwide, an estimated 200million girls and women have been subjected to female genital cutting. Female genital cutting is defined as an intentional injury to the female genitalia without medical justification. The practice occurs in at least 29 countries in Africa, the Middle East, and Asia. In addition, globalization and migration have brought i...

Conformist social learning can have a pronounced impact on the cultural evolution of human societies, and it can shape both the genetic and cultural evolution of human social behavior more broadly. Conformist social learning is beneficial when the social learner and the demonstrators from whom she learns are similar in the sense that the same behav...

Raw data from the experiments. (TXT)

The incentive structure for social learners. (PDF)

Asymmetric Bayesian posteriors related to similarity. (PDF)

Screen shots and excerpts from instructions. (PDF)

Gene-culture coevolution when cognition encodes and processes information about similarity. (PDF)

Instructions used in the experiments. (PDF)

As globalization brings people with incompatible attitudes into contact, cultural conflicts inevitably arise. Little is known about how to mitigate conflict and about how the conflicts that occur can shape the cultural evolution of the groups involved. Female genital cutting is a prominent example. Governments and international agencies have promot...

The error management model of altruism in one-shot interactions provides an influential explanation for one of the most controversial behaviors in evolutionary social science. The model posits that one-shot altruism arises from a domain-specific cognitive bias that avoids the error of mistaking a long-term relationship for a one-shot interaction. O...

For cooperation to evolve, some mechanism must limit the rate at which cooperators are exposed to defectors. Only then can the advantages of mutual cooperation outweigh the costs of being exploited. Although researchers widely agree on this, they disagree intensely about which evolutionary mechanisms can explain the extraordinary cooperation exhibi...

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The World Health Organization defines female genital cutting as any procedure that removes or injures any part of a female's external genitalia for nonmedical reasons (1). Cutting brings no documented health benefits and leads to serious health problems. Across six African countries, for example, a cohort of 15-year-old girls is expected to lose ne...

The evolutionary legacy hypothesis proposes that an evolved reciprocity-based psychology affects human behavior in anonymous one-shot interactions when reciprocity is not explicitly possible. Empirical support rests on experiments showing that altruism among adults increases in the presence of stylized eye spots or faces. Such stimuli do not affect...

Anthropologists have documented substantial cross-society variation in people's willingness to treat strangers with impartial, universal norms versus favoring members of their local community. Researchers have proposed several adaptive accounts for these differences. One variant of the pathogen stress hypothesis predicts that people will be more li...

Evolutionary theory predicts that observable traits should evolve to reliably indicate unobservable behavioral tendencies in coordination games but not social dilemmas. We conducted a two-part study to test this idea. First, we recorded 60-s videos of participants, and then these participants played a stag hunt game or a prisoner’s dilemma. Subsequ...

The evolution of cooperation requires some mechanism that reduces the risk of exploitation for cooperative individuals. Recent studies have shown that men with wide faces are anti-social, and they are perceived that way by others. This suggests that people could use facial width to identify anti-social men and thus limit the risk of exploitation. T...

We investigated the effect of religion on generosity, interpersonal trust, and cooperation by using games developed by experimental economists (Dictator, Trust, and Public Goods). In these experiments, individuals were paired or grouped with unknown strangers to test the degree to which religion promotes prosocial behavior. We evaluated group- and...

Recent evidence indicates that priming participants with religious concepts promotes prosocial sharing behaviour. In the present study, we investigated whether religious priming also promotes the costly punishment of unfair behaviour. A total of 304 participants played a punishment game. Before the punishment stage began, participants were sublimin...

Error management theory is a theory of considerable scope and emerging influence. The theory claims that cognitive biases do not necessarily reflect flaws in evolutionary design, but that they may be best conceived as design features. Unfortunately, existing accounts are vague with respect to the key concept of bias. The result is that it is unclea...

Cultural boundaries have often been the basis for discrimination, nationalism, religious wars, and genocide. Little is known, however, about how cultural groups form or the evolutionary forces behind group affiliation and ingroup favoritism. Hence, we examine these forces experimentally and show that arbitrary symbolic markers, though initially mea...

The existence of social learning has been confirmed in diverse taxa, from apes to guppies. In order to advance our understanding of the consequences of social transmission and evolution of behavior, however, we require statistical tools that can distinguish among diverse social learning strategies. In this paper, we advance two main ideas. First, s...

Economic growth theory and theoretical ecology represent independent traditions of modeling aggregate consumer-resource systems. Both focus on different but equally important forces underlying the dynamics of human societies. Though the two traditions have unknowingly converged in some ways, they each have curious conventions from the perspective o...

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 “exaggera...

Human cooperation is unparalleled in the animal world and rests on an altruistic concern for the welfare of genetically unrelated strangers. The evolutionary roots of human altruism, however, remain poorly understood. Recent evidence suggests a discontinuity between humans and other primates because individual chimpanzees do not spontaneously provi...

We present a new method for quantitatively documenting concerns for economic fairness. In particular we focus on the method’s potential for identifying variation in prosociality within and across societies. Specifically, we conducted multiple dictator games per player in two small-scale societies. Each game presented the decision maker with a choic...