Understanding urbanicity: how interdisciplinary methods help to unravel the effects of the city on mental health.

Twenty-first century urbanization poses increasing challenges for mental health. Epidemiological studies have shown that mental health problems often accumulate in urban areas, compared to rural areas, and suggested possible underlying causes associated with the social and physical urban environments. Emerging work indicates complex urban effects that depend on many individual and contextual factors at the neighbourhood and country level and novel experimental work is starting to dissect potential underlying mechanisms. This review summarizes findings from epidemiology and population-based studies, neuroscience, experimental and experience-based research and illustrates how a combined approach can move the field towards an increased understanding of the urbanicity-mental health nexus.

Gendered outgroup prejudice: An evolutionary threat management perspective on anti-immigrant bias.

Are male and female immigrants viewed similarly or differently? Consistent with an evolutionary threat management perspective, we suggest that the answer to this question depends upon what types of threats immigrant groups are perceived as posing. In the present study, we compared attitudes toward male and female immigrants from either a violent ecology (e.g., Syria) or a pathogen-rich ecology (e.g., Liberia). We hypothesized that people would have more negative attitudes toward male than female immigrants from a violent ecology, but that attitudes would be similar toward male and female immigrants from a pathogen-rich ecology. Internal meta-analyses of three studies (total N = 1,488) were in line with our hypothesis. They showed that attitudes toward male immigrants from a violent ecology were more negative than attitudes toward female immigrants from the same ecology. In contrast, attitudes toward male and female immigrants were similar when those immigrants came from a pathogen-rich ecology. Our findings are consistent with an evolutionary threat management perspective on outgroup prejudice and are aligned with the male warrior hypothesis: Attitudes toward male versus female outgroup members vary with the potential threats these outgroups pose.

The Napoleon Complex: When Shorter Men Take More.

Inspired by an evolutionary psychological perspective on the Napoleon complex, we hypothesized that shorter males are more likely to show indirect aggression in resource competitions with taller males. Three studies provide support for our interpretation of the Napoleon complex. Our pilot study shows that men (but not women) keep more resources for themselves when they feel small. When paired with a taller male opponent (Study 1), shorter men keep more resources to themselves in a game in which they have all the power (dictator game) versus a game in which the opponent also has some power (ultimatum game). Furthermore, shorter men are not more likely to show direct, physical aggression toward a taller opponent (Study 2). As predicted by the Napoleon complex, we conclude that (relatively) shorter men show greater behavioral flexibility in securing resources when presented with cues that they are physically less competitive. Theoretical and practical implications are discussed.

Hormonal underpinnings of status conflict: Testosterone and cortisol are related to decisions and satisfaction in the hawk-dove game.

A contribution to a special issue on Hormones and Human Competition.Testosterone is theorized to influence status-seeking behaviors such as social dominance and competitive behavior, but supporting evidence is mixed. The present study tested the roles of testosterone and cortisol in the hawk-dove game, a dyadic economic decision-making paradigm in which earnings depend on one's own and the other player's choices. If one person selects the hawk strategy and the other person selects the dove strategy, the player who selected hawk attains a greater financial pay-off (status differentiation). The worst financial outcome occurs when both players choose the hawk strategy (status confrontation). Ninety-eight undergraduate students (42 men) provided saliva samples and played ten rounds of the hawk-dove game with another same-sex participant. In support of the hypothesis that testosterone is related to status concern, individuals higher in basal testosterone made more hawk decisions - decisions that harmed the other player. Acute decreases in cortisol were also associated with more hawk decisions. There was some empirical support for the dual-hormone hypothesis as well: basal testosterone was positively related to satisfaction in the game among low basal-cortisol individuals but not among high basal-cortisol individuals. There were no significant sex differences in these hormonal effects. The present findings align with theories of hormones and status-seeking behavior at the individual level, but they also open up new avenues for research on hormone profiles at the collective level. Our results suggest that the presence of two or more high-testosterone members increases the likelihood of status confrontations over a limited resource that can undermine collective outcomes.

The motivations and reputational consequences of spreading conspiracy theories.

Some people deliberately spread conspiracy theories. What are the reputational benefits and costs of doing so? The Adaptive-Conspiracism hypothesis proposes that it pays to be vigilant against possible conspiracies, especially in case of intergroup threat. Those who spread conspiracy theories may therefore be seen as valuable group members. Few studies have focused on the reputational impact of spreading a conspiracy theory. We conducted five studies (NPilot = 303; NStudy1 = 388; NStudy2 = 560; NStudy3 = 391; NStudy4 = 373) where participants rated a conspiracy spreader (vs. a neutral person) on a range of personality traits in different intergroup contexts. The results indicated that conspiracy spreaders were consistently perceived as more dominant and less warm than people making non-conspiratorial claims about certain events. Moreover, intergroup conflict attenuated the negative effects of spreading conspiracy theories on competence and warmth. These findings support the notion that besides drawbacks, spreading conspiracy theories can have benefits for the spreader's reputation, particularly during an intergroup conflict.

Mind the gap: Development and validation of an evolutionary mismatched lifestyle scale and its impact on health and wellbeing.

Identifying an integrative framework that could appropriately delineate underlying mechanisms and individual risk/protective factors for human health has remained elusive. Evolutionary mismatch theory provides a comprehensive, integrative model for understanding the underlying causes and mechanisms of a wide range of modern health and well-being problems, ranging from obesity to depression. Despite growing interest regarding its importance though, no psychometrically-sound measure of evolutionary mismatch yet exists to facilitate research and intervention. To construct such a scale, aimed at gauging individual differences in the extent to which people's modern lifestyles are mismatched with ancestral conditions, we conducted four studies (a pilot study, followed by 3 main studies, with a final sample of 1901 participants across the main studies). Results from exploratory and confirmatory factor analyses have produced a 36-item evolutionary mismatched lifestyle scale (EMLS) with 7 subdomains of mismatched behaviours (e.g., diet, physical activity, relationships, social media use) that is psychometrically sound. Further, the EMLS is associated with physical, mental and subjective health. We explore the potential of the EMLS as a tool for examining interpersonal and cultural variations in health and wellbeing, while also discussing the limitations of the scale and future directions in relation to further psychometric examinations.

Do natural landscapes reduce future discounting in humans?

An important barrier to enduring behavioural change is the human tendency to discount the future. Drawing on evolutionary theories of life history and biophilia, this study investigates whether exposure to natural versus urban landscapes affects people's temporal discount rates. The results of three studies, two laboratory experiments and a field study reveal that individual discount rates are systematically lower after people have been exposed to scenes of natural environments as opposed to urban environments. Further, this effect is owing to people placing more value on the future after nature exposure. The finding that nature exposure reduces future discounting-as opposed to exposure to urban environments-conveys important implications for a range of personal and collective outcomes including healthy lifestyles, sustainable resource use and population growth.

Facial aesthetic minimally invasive procedure: More than just vanity, a social-psychological approach.

BACKGROUND: Due to the great importance of the face in social interaction, minimally invasive treatments can-besides their ability to rejuvenate and enhance beauty-also change the way facial impressions of a person are perceived. In recent literature, three main character traits (attractiveness, trustworthiness, and competence) and subdomains essential for facial perception were described. OBJECTIVE: To investigate whether minimally invasive procedures truly influence different character traits when evaluated by independent, objective observers. METHODS: Photographs of n = 34 female faces before and after treatment with injectable fillers and botulinum toxin were rated by 393 individuals without aesthetic background with regards to different character traits on a 7-point Likert scale. Tests for dimensionality were performed, and composite scores of the impressions underlying each of the three dimensions were created and compared using within-subjects t tests. RESULTS: Treatments statistically significantly improved the overarching character trait domains attractiveness, trustworthiness, and competence in posttreatment photographs compared with pretreatment. Posttreatment ratings of the respective subdomains also showed a statistically significant difference compared with pretreatment photographs, with the exception of the subdomain dominance which failed to reach statistical significance. CONCLUSION: Impressions of facial attractiveness, trustworthiness, and competence can be improved by injectables while the naturalness of the face is left intact. An implication is that the improvement of traits highly relevant to social interaction will accommodate the patient's desires for beautification and rejuvenation.

Social laughter is correlated with an elevated pain threshold.

Although laughter forms an important part of human non-verbal communication, it has received rather less attention than it deserves in both the experimental and the observational literatures. Relaxed social (Duchenne) laughter is associated with feelings of wellbeing and heightened affect, a proximate explanation for which might be the release of endorphins. We tested this hypothesis in a series of six experimental studies in both the laboratory (watching videos) and naturalistic contexts (watching stage performances), using change in pain threshold as an assay for endorphin release. The results show that pain thresholds are significantly higher after laughter than in the control condition. This pain-tolerance effect is due to laughter itself and not simply due to a change in positive affect. We suggest that laughter, through an endorphin-mediated opiate effect, may play a crucial role in social bonding.

Psychological barriers to effective altruism: An evolutionary perspective.

People usually engage in (or at least profess to engage in) altruistic acts to benefit others. Yet, they routinely fail to maximize how much good is achieved with their donated money and time. An accumulating body of research has uncovered various psychological factors that can explain why people's altruism tends to be ineffective. These prior studies have mostly focused on proximate explanations (e.g. emotions, preferences, lay beliefs). Here, we adopt an evolutionary perspective and highlight how three fundamental motives - parochialism, status, and conformity - can explain many seemingly disparate failures to do good effectively. Our approach outlines ultimate explanations for ineffective altruism, and we illustrate how fundamental motives can be leveraged to promote more effective giving.

Construct and Predictive Validity of an Assessment Game to Measure Honesty-Humility.

Research on commercial computer games has demonstrated that in-game behavior is related to the players' personality profiles. However, this potential has not yet been fully utilized for personality assessments. Hence, we developed an applied (i.e., serious) assessment game to assess the Honesty-Humility personality trait. In two studies, we demonstrate that this game adequately assesses Honesty-Humility. In Study 1 (N = 116), we demonstrate convergent validity of the assessment game with self-reported Honesty-Humility and divergent validity with the other HEXACO traits and cognitive ability. In Study 2 (N = 287), we replicate the findings from Study 1, and also demonstrate that the assessment game shows incremental validity-beyond self-reported personality-in the prediction of cheating for financial gain, but not of counterproductive work and unethical behaviors. The findings demonstrate that assessment games are promising tools for personality measurement in applied contexts.

Sex bias in intergroup conflict and collective movements among social mammals: male warriors and female guides.

Intergroup conflict is a major evolutionary force shaping animal and human societies. Males and females should, on average, experience different costs and benefits for participating in collective action. Specifically, among mammals, male fitness is generally limited by access to mates whereas females are limited by access to food and safety. Here we analyse sex biases among 72 species of group-living mammals in two contexts: intergroup conflict and collective movements. Our comparative phylogenetic analyses show that the modal mammalian pattern is male-biased participation in intergroup conflict and female-biased leadership in collective movements. However, the probability of male-biased participation in intergroup conflicts decreased and female-biased participation increased with female-biased leadership in movements. Thus, female-biased participation in intergroup conflict only emerged in species with female-biased leadership in collective movements, such as in spotted hyenas and some lemurs. Sex differences are probably attributable to costs and benefits of participating in collective movements (e.g. towards food, water, safety) and intergroup conflict (e.g. access to mates or resources, risk of injury). Our comparative review offers new insights into the factors shaping sex bias in leadership across social mammals and is consistent with the 'male warrior hypothesis' which posits evolved sex differences in human intergroup psychology. This article is part of the theme issue 'Intergroup conflict across taxa'.

The evolutionary psychology of climate change behaviors: Insights and applications.

We examine climate-related activities through an evolutionary psychology lens, zooming in on factors that motivate or discourage people to behave sustainably to mitigate climate change. Complementing current knowledge, we discuss five core ancestral psychological motivations that shape people's environmental decisions in fundamental ways. We review recent studies that explore how evolved psychological mechanisms related to self-interest, status, sensing, discounting tendencies, and social imitation can be used to promote proenvironmental behavior. We discuss the potential strengths and limitations of evolutionary-based behavioral interventions and briefly reflect on outstanding research questions that can further the integration of evolutionary approaches into mainstream environmental psychology.

The triad model of follower needs: theory and review.

Humans have an evolved flexible followership psychology that enables them to select different leaders in different contexts, depending on their needs. We distinguish a triad of follower needs: (i) guidance into a shared direction, (ii) active protection against threats, and (iii) judicious dispute settlement. These needs relate to critical group coordination challenges described in biology and anthropology and to different evolutionary leadership theories. We describe the contexts, in which these needs emerge, the characteristics of leaders who meet these needs, and the potential risks of following these leaders. We end by discussing the potential of our theory to aid the understanding of leadership in modern organizations, female leadership, leader manipulation of needs, and individual differences between followers.

Constraining free riding in public goods games: designated solitary punishers can sustain human cooperation.

Much of human cooperation remains an evolutionary riddle. Unlike other animals, people frequently cooperate with non-relatives in large groups. Evolutionary models of large-scale cooperation require not just incentives for cooperation, but also a credible disincentive for free riding. Various theoretical solutions have been proposed and experimentally explored, including reputation monitoring and diffuse punishment. Here, we empirically examine an alternative theoretical proposal: responsibility for punishment can be borne by one specific individual. This experiment shows that allowing a single individual to punish increases cooperation to the same level as allowing each group member to punish and results in greater group profits. These results suggest a potential key function of leadership in human groups and provides further evidence supporting that humans will readily and knowingly behave altruistically.

Despotism, democracy, and the evolutionary dynamics of leadership and followership.

Responds to comments made by George B. Graen and Stephen J. Guastello on the current author's article Leadership, followership, and evolution: Some lessons from the past by Van Vugt, Hogan, and Kaiser. In the original article my co-authors and I proposed a new way of thinking about leadership, informed by evolutionary (neo-Darwinian) theory. In the first commentary, Graen noted that we ignored a number of recently developed psychological theories of leadership that take into account the leader-follower relationship, most notably LMX theory. LMX theory asserts that leadership effectiveness and team performance are affected by the quality of working relationships between superior and subordinates. Because the original article primarily dealt with questions about the origins of leadership--the phylogenetic and evolutionary causes--we had to be concise in our review of proximate psychological theories of leadership. In the second commentary, Guastello concurred with the importance of an evolutionary game analysis for studying leadership but disagreed with certain details of our analysis. (PsycINFO Database Record (c) 2009 APA, all rights reserved).

A Dual Model of Leadership and Hierarchy: Evolutionary Synthesis.

From the popularity of authoritarian political leaders to the under-representation of women in boardrooms, leadership is an important theme in current human social affairs. Leadership is also a prominent research topic in the biological, social, and cognitive sciences. However, these active literatures have evolved somewhat independently and there is a need for synthesis. A comparative-evolutionary approach can integrate seemingly divergent perspectives by making a distinction between two leadership styles, prestige and dominance, that have contrasting expressions, functions, histories, and neural and developmental pathways. The distinction may help to resolve various scientific puzzles, such as: (i) opposing views on the different functions and expressions of leadership; (ii) the appeal of dominance-style leaders; and (iii) sex biases in leadership emergence in modern society.