Coalitions and conflict: A longitudinal analysis of men's politics

Evidence of direct and indirect reciprocity in network-structured economic games

Formal theoretical models propose that cooperative networks can be maintained when individuals condition behavior on social standing. Here, we empirically examine the predictions of such models of positive and negative indirect reciprocity using a suite of network-structured economic games in four rural Colombian communities (Nind = 496 individuals, Nobs = 53,876 ratings/transfers). We observe that, at a dyadic-level, individuals have a strong tendency to exploit and punish others in bad standing (e.g., those perceived as selfish), and allocate resources to those in good standing (e.g., those perceived as generous). These dyadic findings scale to a more generalized, community level, where reputations for being generous are associated with receipt of allocations, and reputations for being selfish are associated with receipt of punishment. These empirical results illustrate the roles that both positive and negative reciprocity, and costly punishment, play in sustaining community-wide cooperation networks.

Religiosity and gender bias structure social networks

The number of studies examining gender differences in the social relationship rewards associated with costly religious practice has been surprisingly low. Here, we use data from 289 residents of an agricultural Tibetan village to assess whether individuals are more inclined to establish supportive relationships with religious individuals in general and to investigate the gender disparities in the relationship between religiosity and personal network characteristics. Our results reveal that participation in religious rituals contributes to the overall development of social support networks. The benefits to personal networks, however, seem to be contingent upon gender. For resource-intensive, infrequent religious rituals such as distant pilgrimages, males seem to benefit slightly more in terms of elevated in-degree values in their personal networks, despite similar levels of investment as females. In contrast, for daily, low-cost religious practices requiring ongoing participation, both genders obtain similar increases in in-degree values through regular engagement. It becomes more challenging for women to increase their status in communities when the effort invested in religious rituals yields smaller rewards compared with the same effort by men, contributing to ongoing gender inequality. These findings highlight the importance of examining the particular characteristics of religious rituals and the gender disparities in the associated rewards.

Women's subsistence networks scaffold cultural transmission among BaYaka foragers in the Congo Basin

In hunter-gatherer societies, women's subsistence activities are crucial for food provisioning and children's social learning but are understudied relative to men's activities. To understand the structure of women's foraging networks, we present 230 days of focal-follow data in a BaYaka community. To analyze these data, we develop a stochastic blockmodel for repeat observations with uneven sampling. We find that women's subsistence networks are characterized by cooperation between kin, gender homophily, and mixed age-group composition. During early childhood, individuals preferentially coforage with adult kin, but those in middle childhood and adolescence are likely to coforage with nonkin peers, providing opportunities for horizontal learning. By quantifying the probability of coforaging ties across age classes and relatedness levels, our findings provide insights into the scope for social learning during women's subsistence activities in a real-world foraging population and provide ground-truth values for key parameters used in formal models of cumulative culture.

Lifting Me Up or Tearing You Down? The Role of Prestige and Dominance in Benign Versus Malicious Envy

Dominance and prestige are two strategies people use to regulate their social rank within group hierarchies. Despite a growing literature on dominance- and prestige-oriented leaders, little is known about how those strategies operate among people lower in social rank. Four studies tested the hypothesis that, among subordinates, dominance and prestige are associated with high levels of malicious and benign envy, respectively. Individual differences in prestige were positively and independently associated with benign envy, and negatively associated with malicious envy. Individual differences in dominance were positively and independently associated with both malicious and benign envy. Two experiments demonstrated that activating a prestige-oriented mindset (relative to a dominance-oriented mindset) caused people to display higher levels of benign envy. No experimental effects on malicious envy were observed. Theories of prestige and dominance provide a useful framework for understanding ways in which subordinate group members strive for high social rank.

The interdependence of relational and material wealth inequality in Pemba, Zanzibar

The extent of inequality in material wealth across different types of societies is well established. Less clear, however, is how material wealth is associated with relational wealth, and the implications of such associations for material wealth inequality. Theory and evidence suggest that material wealth both guides, and is patterned by, relational wealth. While existing comparative studies typically assume complementarity between different types of wealth, such associations may differ for distinct kinds of relational wealth. Here, we first review the literature to identify how and why different forms of relational wealth may align. We then turn to an analysis of household-level social networks (food sharing, gender-specific friendship and gender-specific co-working networks) and material wealth data from a rural community in Pemba, Zanzibar. We find that (i) the materially wealthy have most relational ties, (ii) the associations between relational and material wealth-as well as relational wealth more generally-are patterned by gender differences, and (iii) different forms of relational wealth have similar structural properties and are closely aligned. More broadly, we show how examining the patterning of distinct types of relational wealth provides insights into how and why inequality in material wealth remains muted in a community undergoing rapid economic change. This article is part of the theme issue 'Evolutionary ecology of inequality'.

Status-impact assessment: is accuracy linked with status motivations?

Status hierarchies are ubiquitous across cultures and have been over deep time. Position in hierarchies shows important links with fitness outcomes. Consequently, humans should possess psychological adaptations for navigating the adaptive challenges posed by living in hierarchically organised groups. One hypothesised adaptation functions to assess, track, and store the status impacts of different acts, characteristics and events in order to guide hierarchy navigation. Although this status-impact assessment system is expected to be universal, there are several ways in which differences in assessment accuracy could arise. This variation may link to broader individual difference constructs. In a preregistered study with samples from India (N = 815) and the USA (N = 822), we sought to examine how individual differences in the accuracy of status-impact assessments covary with status motivations and personality. In both countries, greater overall status-impact assessment accuracy was associated with higher status motivations, as well as higher standing on two broad personality constructs: Honesty-Humility and Conscientiousness. These findings help map broad personality constructs onto variation in the functioning of specific cognitive mechanisms and contribute to an evolutionary understanding of individual differences.

Life History Strategies, Prestige, and Dominance: An Evolutionary Developmental View of Social Hierarchy

Although evidence documents the use of prestige and dominance for navigating group hierarchies, little is known about factors that explain people's orientation toward prestige versus dominance. The current research applied a life history perspective to assess the role life history strategies play in prestige and dominance. Four studies document associations between adopting a slow life history strategy and having an orientation toward prestige. We also saw some (less consistent) evidence that people's orientation toward prestige is rooted in exposure to predictable childhood environments, a known antecedent of slow life history strategies. Although we observed some evidence that exposure to unpredictable childhood environments was associated with dominance, there was little direct evidence that this relationship was explained by a fast life history strategy. Findings suggest that an orientation toward prestige is likely to be observed in people with a slow life history, who adopt a long-term time horizon for planning and decision-making.

New perspectives on the evolution of women's cooperation

A holistic, evolutionary framework about human cooperation must incorporate information about women's cooperative behaviour. Yet, most empirical research on human cooperation has centered on men's behaviour or been derived from experimental studies conducted in western, industrialized populations. These bodies of data are unlikely to accurately represent human behavioural diversity. To address this gap and provide a more balanced view of human cooperation, this issue presents substantial new data and multi-disciplinary perspectives to document the complexity of women's cooperative behaviour. Research in this issue 1) challenges narratives about universal gender differences in cooperation, 2) reconsiders patrilocality and access to kin as constraints on women's cooperation, 3) reviews evidence for a connection between social support and women's health and 4) examines the phylogenetic roots of female cooperation. Here, we discuss the steps taken in this issue toward a more complete and evidence-based understanding of the role that cooperation plays in women's and girls' lives and in building human sociality. This article is part of the theme issue 'Cooperation among women: evolutionary and cross-cultural perspectives'.

Workplace gossip and the evolution of friendship relations: the role of complex contagion

Gossip is a pervasive phenomenon in organizations causing many individuals to have second-hand information about their colleagues. However, whether it is used to inform friendship choices (i.e., friendship creation, friendship maintenance, friendship discontinuation) is not that evident. This paper articulates and empirically tests a complex contagion model to explain how gossip, through its reputational effects, can affect the evolution of friendship ties. We argue that hearing gossip from more than a single sender (and about several targets) impacts receivers’ friendships with the gossip targets. Hypotheses are tested in a two-wave sociometric panel study among 148 employees in a Dutch childcare organization. Stochastic actor-oriented models reveal positive gossip favors receiver-target friendships, whereas negative gossip inhibits them. We also find evidence supporting that, for damaging relationships, negative gossip needs to originate in more than a single sender. Positive gossip about a high number of targets discourages friendships with colleagues in general, while negative gossip about many targets produces diverging trends. Overall, the study demonstrates that second-hand information influences the evolution of expressive relations. It also underscores the need to refine and extend current theorizing concerning the multiple (and potentially competing) psychological mechanisms causing some of the observed effects.

Towards a computational network theory of social groups

Network theory is necessary for the realization of cognitive representations and resulting empirical observations of social groups. We propose that the triadic primitives denoting individual roles are multilayer, with positive and negative relations feeding into cost-benefit calculations. Through this, we advance a computational theory that generalizes to different scales and to contexts where conflict is not present.

Sex Differences in Fearful Personality Traits Are Mediated by Physical Strength

Across cultures, women reliably exhibit higher levels of Neuroticism than men. Recent work shows that this sex difference, particularly in Neuroticism’s anxiety facet, is partly mediated by the sex difference in physical strength. We build on this finding by testing pre-registered predictions of mediation by physical strength of the sex differences in HEXACO Emotionality and its Anxiety and Fearfulness facets (HEXACO stands for the factors of honesty–humility, emotionality, extraversion, agreeableness, conscientiousness, and openness to experience). Facultative calibration models predict that levels of these two facets, but not necessarily Emotionality’s other facets, will be adaptively adjusted during ontogeny to a person’s relative physical formidability. Results from five samples of U.S. undergraduates (total N = 1,399) showed that strength mediated the sex difference (women > men) in Emotionality and all its facets, but that the mediation effect was strongest for Fearfulness and weakest for Sentimentality. Overall, findings are consistent with the hypothesis that physical strength explains sex differences found in fearful and anxious personality traits.

Political Alliance Formation and Cooperation Networks in the Utah State Legislature

Social network analysis has become an increasingly important tool among political scientists for understanding legislative cooperation in modern, democratic nation-states. Recent research has demonstrated the influence that group affinity (homophily) and mutual exchanges (reciprocity) have in structuring political relationships. However, this literature has typically focused on political cooperation where costs are low, relationships are not exclusive, and/or partisan competition is high. Patterns of legislative behavior in alternative contexts are less clear and remain largely unexamined. Here, we compare theoretical expectations of cooperation in these contexts from the political and biosocial sciences and implement the first assessment of political alliance formation in a novel legislative environment where costs to cooperation are high and party salience low. We implement a stochastic actor-oriented model (SAOM) to examine bill floor sponsorship, a process in which a "floor sponsor" becomes the exclusive advocate for a colleague's piece of legislation, in the Utah state legislature from 2005 to 2008-a context in which gender (male) and political party (Republican) supermajorities exist. We find that (1) party and gender homophily predict who legislators recruit as floor sponsors, whereas seniority does not, and (2) legislators frequently engage in reciprocal exchanges of floor sponsorship. In addition, whereas gender homophily increases the likelihood of reciprocity, party homophily decreases it. Our findings suggest that when the cost of cooperation is high, political actors use in-group characteristics for initiating alliances, but once a cooperative relationship is established with an out-group political member, it is reinforced through repeated exchanges. These findings may be useful for understanding the rise of political polarization and gridlock in democracies internationally.

Correlates of conflict resolution across cultures

Conflicts are ubiquitous between individuals as well as between groups. Effective conflict resolution is essential for individual well-being and group functioning and often involves leadership dynamics. The evolutionary human sciences have suggested that conflict resolution is shaped by psychological heuristics, norms and ecology. There are limited empirical data, however, on conflict resolution across cultures. Using a cross-cultural database of 109 leadership dimensions coded from over 1200 text records from the eHRAF ethnographic database, exploratory analyses investigated correlates of conflict resolution. The results revealed greater evidence of conflict resolution among kin groups than political groups and greater evidence of within-group conflict resolution than between-group, which did not vary across subsistence strategies or group contexts, with two exceptions - military group conflicts were biased towards between-group contexts and religious groups biased towards within-group contexts. The strongest predictors of conflict-resolution services were other prosocial functions and included group representation and providing counsel, protection and punishment, as well as qualities of interpersonal skills and fairness. Followers received social service benefits and reduced risk of harm. For leaders who resolve conflicts, status and social benefits were potential negative predictors. These results provide a comparative view of the correlates of conflict resolution suggesting diversity across social contexts.