2-D sex images elicit mate copying in fruit flies.

Although the environment is three-dimensional (3-D), humans are able to extract subtle information from two-dimensional (2-D) images, particularly in the domain of sex. However, whether animals with simpler nervous systems are capable of such information extraction remains to be demonstrated, as this ability would suggest a functional generalisation capacity. Here, we performed mate-copying experiments in Drosophila melanogaster using 2-D artificial stimuli.

Novel theory of mind task demonstrates representation of minds in mental state inference.

Theory of mind (ToM), the ability to represent the mental states of oneself and others, is argued to be central to human social experience, and impairments in this ability are thought to underlie several psychiatric and developmental conditions. To examine the accuracy of mental state inferences, a novel ToM task was developed, requiring inferences to be made about the mental states of 'Targets', prior participants who took part in a videoed mock interview. Participants also made estimates of the Targets' personality traits.

Female cooperative labour networks in hunter-gatherers and horticulturalists.

Cooperation in food acquisition is a hallmark of the human species. Given that costs and benefits of cooperation vary among production regimes and work activities, the transition from hunting-and-gathering to agriculture is likely to have reshaped the structure of cooperative subsistence networks. Hunter-gatherers often forage in groups and are generally more interdependent and experience higher short-term food acquisition risk than horticulturalists, suggesting that cooperative labour should be more widespread and frequent for hunter-gatherers.

Repercussions of patrilocal residence on mothers' social support networks among Tsimane forager-farmers.

While it is commonly thought that patrilocality is associated with worse outcomes for women and their children due to lower social support, few studies have examined whether the structure of female social networks covaries with post-marital residence. Here, we analyse scan sample data collected among Tsimane forager-farmers. We compare the social groups and activity partners of 181 women residing in the same community as their parents, their husband's parents, both or neither.

Shifts in evolutionary balance of phenotypes under environmental changes.

Environments shape communities by driving individual interactions and the evolutionary outcome of competition. In static, homogeneous environments a robust, evolutionary stable, outcome is sometimes reachable. However, inherently stochastic, this evolutionary process need not stabilize, resulting in a dynamic ecological state, often observed in microbial communities.

Belief changes associated with psychedelic use.

Background: Psychedelic use is anecdotally associated with belief changes, although few studies have tested these claims.

Aim: Characterize a broad range of psychedelic occasioned belief changes.

Survey: A survey was conducted in 2374 respondents who endorsed having had a belief changing psychedelic experience.

Corrupt third parties undermine trust and prosocial behaviour between people.

Corruption is a pervasive phenomenon that affects the quality of institutions, undermines economic growth and exacerbates inequalities around the globe. Here we tested whether perceiving representatives of institutions as corrupt undermines trust and subsequent prosocial behaviour among strangers. We developed an experimental game paradigm modelling representatives as third-party punishers to manipulate or assess corruption and examine its relationship with trust and prosociality (trust behaviour, cooperation and generosity).

Conformity in mate choice, the overlooked social component of animal and human culture.

Although conformity as a major driver for human cultural evolution is a well-accepted and intensely studied phenomenon, its importance for non-human animal culture has been largely overlooked until recently. This limited for decades the possibility of studying the roots of human culture. Here, we provide a historical review of the study of conformity in both humans and non-human animals.

Subjective selection and the evolution of complex culture.

Why is culture the way it is? Here I argue that a major force shaping culture is subjective (cultural) selection, or the selective retention of cultural variants that people subjectively perceive as satisfying their goals. I show that people evaluate behaviors and beliefs according to how useful they are, especially for achieving goals. As they adopt and pass on those variants that seem best, they iteratively craft culture into increasingly effective-seeming forms.

Eye movements reveal that low confidence precedes deliberation.

Contemporary dual-process models of reasoning maintain that there are two types of thinking -intuitive and deliberative -and that low confidence often leads to deliberation. Previous studies examining the confidence -deliberation relationship have been limited by (1) issues of endogeneity and between-subject comparisons, which we address in this study through debias training and (2) measures of confidence that are taken relatively late in the reasoning process, which we address by measuring confidence via real-time eye-tracking. Self-reported and eye-tracked confidence were both negatively related to deliberative thinking.

Predicting attitudinal and behavioral responses to COVID-19 pandemic using machine learning.

At the beginning of 2020, COVID-19 became a global problem. Despite all the efforts to emphasize the relevance of preventive measures, not everyone adhered to them. Thus, learning more about the characteristics determining attitudinal and behavioral responses to the pandemic is crucial to improving future interventions.

Polarized Citizen Preferences for the Ethical Allocation of Scarce Medical Resources in 20 Countries.

Unlabelled: When medical resources are scarce, clinicians must make difficult triage decisions. When these decisions affect public trust and morale, as was the case during the COVID-19 pandemic, experts will benefit from knowing which triage metrics have citizen support. We conducted an online survey in 20 countries, comparing support for 5 common metrics (prognosis, age, quality of life, past and future contribution as a health care worker) to a benchmark consisting of support for 2 no-triage mechanisms (first-come-first-served and random allocation).

Acoustic regularities in infant-directed speech and song across cultures.

When interacting with infants, humans often alter their speech and song in ways thought to support communication. Theories of human child-rearing, informed by data on vocal signalling across species, predict that such alterations should appear globally. Here, we show acoustic differences between infant-directed and adult-directed vocalizations across cultures.

Emotion may predict susceptibility to fake news but emotion regulation does not seem to help.

Misinformation is a serious concern for societies across the globe. To design effective interventions to combat the belief in and spread of misinformation, we must understand which psychological processes influence susceptibility to misinformation. This paper tests the widely assumed - but largely untested - claim that emotionally provocative headlines are associated with worse ability to identify true versus false headlines.

Religious celibacy brings inclusive fitness benefits.

The influence of inclusive fitness interests on the evolution of human institutions remains unclear. Religious celibacy constitutes an especially puzzling institution, often deemed maladaptive. Here, we present sociodemographic data from an agropastoralist Buddhist population in western China, where parents sometimes sent a son to the monastery.

The importance of population heterogeneities in detecting social learning as the foundation of animal cultural transmission.

High levels of within-population behavioural variation can have drastic demographic consequences, thus changing the evolutionary fate of populations. A major source of within-population heterogeneity is personality. Nonetheless, it is still relatively rarely accounted for in social learning studies that constitute the most basic process of cultural transmission.

Understanding hunter-gatherer cultural evolution needs network thinking.

Hunter-gatherers past and present live in complex societies, and the structure of these can be assessed using social networks. We outline how the integration of new evidence from cultural evolution experiments, computer simulations, ethnography, and archaeology open new research horizons to understand the role of social networks in cultural evolution.

Socioecology shapes child and adolescent time allocation in twelve hunter-gatherer and mixed-subsistence forager societies.

A key issue distinguishing prominent evolutionary models of human life history is whether prolonged childhood evolved to facilitate learning in a skill- and strength-intensive foraging niche requiring high levels of cooperation. Considering the diversity of environments humans inhabit, children's activities should also reflect local social and ecological opportunities and constraints. To better understand our species' developmental plasticity, the present paper compiled a time allocation dataset for children and adolescents from twelve hunter-gatherer and mixed-subsistence forager societies (n = 690; 3-18 years; 52% girls).

Social preferences or sacred values? Theory and evidence of deontological motivations.

Recent advances in economic theory, largely motivated by experimental findings, have led to the adoption of models of human behavior where decision-makers take into consideration not only their own payoff but also others' payoffs and any potential consequences of these payoffs. Investigations of deontological motivations, where decision-makers make their choice based on not only the consequences of a decision but also the decision per se, have been rare. We provide a formal interpretation of major moral philosophies and a revealed preference method to distinguish the presence of deontological motivations from a purely consequentialist decision-maker whose preferences satisfy first-order stochastic dominance.

Evidence for third-party mediation but not punishment in Mentawai justice.

Researchers argue that third parties help sustain human cooperation, yet how they contribute remains unclear, especially in small-scale, politically decentralized societies. Studying justice among Mentawai horticulturalists in Indonesia, we examined evidence for punishment and mediation by third parties. Across a sample of 444 transgressions, we find no evidence of direct third-party punishment.

Situational factors shape moral judgements in the trolley dilemma in Eastern, Southern and Western countries in a culturally diverse sample.

The study of moral judgements often centres on moral dilemmas in which options consistent with deontological perspectives (that is, emphasizing rules, individual rights and duties) are in conflict with options consistent with utilitarian judgements (that is, following the greater good based on consequences). Greene et al. (2009) showed that psychological and situational factors (for example, the intent of the agent or the presence of physical contact between the agent and the victim) can play an important role in moral dilemma judgements (for example, the trolley problem).

'Citizens' Attitudes Under Covid19', a cross-country panel survey of public opinion in 11 advanced democracies.

This article introduces data collected in the Citizens' Attitudes Under Covid-19 Project (CAUCP), which surveyed public opinion throughout the Covid-19 pandemic in 11 democracies between March and December 2020. In this paper, we present a unique cross-country panel survey of citizens' attitudes and behaviors during a worldwide unprecedented health, governance, and economic crisis. This dataset investigates the behavioral and attitudinal consequences of multifaceted Covid19 crisis across time and contexts.

Hunter-gatherer genomes reveal diverse demographic trajectories during the rise of farming in Eastern Africa.

The fate of hunting and gathering populations following the rise of agriculture and pastoralism remains a topic of debate in the study of human prehistory. Studies of ancient and modern genomes have found that autochthonous groups were largely replaced by expanding farmer populations with varying levels of gene flow, a characterization that is influenced by the almost universal focus on the European Neolithic. We sought to understand the demographic impact of an ongoing cultural transition to farming in Southwest Ethiopia, one of the last regions in Africa to experience such shifts.