What is the origin of individual differences in ideology and personality? According to the parasite stress hypothesis, the structure of a society and the values of individuals within it are both influenced by the prevalence of infectious disease within the society's geographical region. High levels of infection threat are associated with more ethnocentric and collectivist social structures and greater adherence to social norms, as well as with socially conservative political ideology and less open but more conscientious personalities. Here we use (...) an agent-based model to explore a specific opportunities-parasites trade-off hypothesis, according to which utility-maximizing agents place themselves at an optimal point on a trade-off between the gains that may be achieved through accessing the resources of geographically or socially distant out-group members through openness to out-group interaction, and the losses arising due to consequently increased risks of exotic infection to which immunity has not been developed. We examine the evolution of cooperation and the formation of social groups within social networks, and we show that the groups that spontaneously form exhibit greater local rather than global cooperative networks when levels of infection are high. It is suggested that the OPTO model offers a first step toward understanding the specific mechanisms through which environmental conditions may influence cognition, ideology, personality, and social organization. (shrink)

Recent studies reveal that violence significantly contributes to explaining individual’s facial preferences. Women who feel at higher risk of violence prefer less-masculine male faces. Given the importance of violence, we explore its influence on people’s preferences for a different physical trait. Masculinity correlates positively with male strength and weight or body mass index. In fact, masculinity and BMI tend to load on the same component of trait perception. Therefore we predicted that individuals’ perceptions of danger from violence will relate to (...) preferences for facial cues to low-BMI. In two studies in Colombia, men and women from Bogota, Medellin, and surrounding communities were shown pairs of faces transformed to epitomize the shape correlates of men with high or low-BMI. The images were of European, Salvadoran, or Colombian men. Participants were asked to choose the face they considered most attractive. Subsequently, participants answered a survey about their health, media access, education level, and experiences/perceptions of violence in study 1 and about specific types of violence in study 2. Results from both studies showed that women who experienced/perceived higher levels of violence preferred faces of low-BMI Salvadoran men. Preferences for low-BMI facial cues were significantly explained by violence, even after controlling for all other variables. These results may reflect women’s strategy to avoid male partners capable of inflicting harm. (shrink)

A total of 80 authors working in a variety of scientific disciplines commented on the theoretical model of CLimate, Aggression, and Self-control in Humans (CLASH). The commentaries cover a wide range of issues, including the logic and assumptions of CLASH, the evidence in support of CLASH, and other possible causes of aggression and violence (e.g., wealth, income inequality, political circumstances, historic circumstances, pathogen stress). Some commentaries also provide data relevant to CLASH. Here we clarify the logic and assumptions of CLASH (...) and discusses its extensions and boundary conditions. We also offer suggestions for future research. Regardless of whether none, some, or all of CLASH is found to be true, we hope it will stimulate future research on the link between climate and human behavior. Climate is one of the most presing issues of our time. (shrink)

Evolutionary anthropology has traditionally focused on the study of small-scale, largely self-sufficient societies. The increasing rarity of these societies underscores the importance of such research yet also suggests the need to understand the processes by which such societies are being lost—what we call “modernization”—and the effects of these processes on human behavior and biology. In this article, we discuss recent efforts by evolutionary anthropologists to incorporate modernization into their research and the challenges and rewards that follow. Advantages include that these (...) studies allow for explicit testing of hypotheses that explore how behavior and biology change in conjunction with changes in social, economic, and ecological factors. In addition, modernization often provides a source of “natural experiments” since it may proceed in a piecemeal fashion through a population. Challenges arise, however, in association with reduced variability in fitness proxies such as fertility, and with the increasing use of relatively novel methodologies in evolutionary anthropology, such as the analysis of secondary data. Confronting these challenges will require careful consideration but will lead to an improved understanding of humanity. We conclude that the study of modernization offers the prospect of developing a richer evolutionary anthropology, by encompassing ultimate and proximate explanations for behavior expressed across the full range of human societies. (shrink)

One of the major benefits of interdisciplinary research is the chance to swap tools between fields, to save having to reinvent the wheel. The fields of language evolution and evolutionary biology have been swapping tools for centuries to the enrichment of both. Here I will discuss three categories of tool swapping: conceptual tools, where analogies are drawn between hypotheses, patterns or processes, so that one field can take advantage of the path cut through the intellectual jungle by the other; theoretical (...) tools, where the machinery developed to process the data in one field is adapted to be applied to the data of the other; and analytical tools, where common problems encountered in both fields can be solved using useful tricks developed by one or the other. I will argue that conceptual tools borrowed from linguistics contributed to the Darwinian revolution in biology; that theoretical tools of evolutionary change can in some cases be applied to both genetic and linguistic data without having to assume the underlying evolutionary processes are exactly the same; and that there are practical problems that have long been recognised in historical linguistics that may be solved by borrowing some useful analytical tools from evolutionary biology. (shrink)