Sexual size dimorphism is generally associated with sexual selection via agonistic male competition in nonhuman primates. These primate models play an important role in understanding the origins and evolution of human behavior. Human size dimorphism is often hypothesized to be associated with high rates of male violence and polygyny. This raises the question of whether human dimorphism and patterns of male violence are inherited from a common ancestor with chimpanzees or are uniquely derived. Here I review patterns of, and causal (...) models for, dimorphism in humans and other primates. While dimorphism in primates is associated with agonistic male mate competition, a variety of factors can affect male and female size, and thereby dimorphism. The causes of human sexual size dimorphism are uncertain, and could involve several non-mutually-exclusive mechanisms, such as mate competition, resource competition, intergroup violence, and female choice. A phylogenetic reconstruction of the evolution of dimorphism, including fossil hominins, indicates that the modern human condition is derived. This suggests that at least some behavioral similarities with Pan associated with dimorphism may have arisen independently, and not directly from a common ancestor. (shrink)

We hypothesize that in modern societies the striving for high positions in the hierarchy of organizations is equivalent to the striving for status and power in historical and traditional societies. Analyzing a sample of 4,491 US men and 5,326 US women, we find that holding a supervisory position or being in charge of hiring and firing is positively associated with offspring count in men but not in women. The positive effect in men is attributable mainly to the higher proportion of (...) childlessness among men in non-supervisory positions and those without the power to hire and fire. This effect is in accordance with the positive relationship between other status indicators and reproductive success found in men from traditional, historical, and modern societies. In women, we further find a curvilinear relationship between income percentile and offspring number by analyzing US census data, indicating that women may strive for resources associated with advancement rather than for status per se. (shrink)

Experimental studies on punishment have sometimes been over-interpreted not only for the reasons Guala lists, but also because of a frequent conflation of proximate and ultimate explanatory levels that Guala's review perpetuates. Moreover, for future analyses we may need a clearer classification of different kinds of punishment.

Minimizing the costs that others impose upon oneself and upon those in whom one has a fitness stake, such as kin and allies, is a key adaptive problem for many organisms. Our ancestors regularly faced such adaptive problems (including homicide, bodily harm, theft, mate poaching, cuckoldry, reputational damage, sexual aggression, and the infliction of these costs on one's offspring, mates, coalition partners, or friends). One solution to this problem is to impose retaliatory costs on an aggressor so that the aggressor (...) and other observers will lower their estimates of the net benefits to be gained from exploiting the retaliator in the future. We posit that humans have an evolved cognitive system that implements this strategy – deterrence – which we conceptualize as a revenge system. The revenge system produces a second adaptive problem: losing downstream gains from the individual on whom retaliatory costs have been imposed. We posit, consequently, a subsidiary computational system designed to restore particular relationships after cost-imposing interactions by inhibiting revenge and motivating behaviors that signal benevolence for the harmdoer. The operation of these systems depends on estimating the risk of future exploitation by the harmdoer and the expected future value of the relationship with the harmdoer. We review empirical evidence regarding the operation of these systems, discuss the causes of cultural and individual differences in their outputs, and sketch their computational architecture. (shrink)

Building on and partially refining previous theoretical work, this paper presents an extended simulation model of ancestral warfare. This model (1) disentangles attack and defense, (2) tries to differentiate more strictly between selfish and altruistic efforts during war, (3) incorporates risk aversion and deterrence, and (4) pays special attention to the role of brutality. Modeling refinements and simulation results yield a differentiated picture of possible evolutionary dynamics. The main observations are: (i) Altruism in this model is more likely to evolve (...) for defenses than for attacks. (ii) Risk aversion, deterrence and the interplay of migration levels and brutality can change evolutionary dynamics substantially. (iii) Unexpectedly, one occasional simulation outcome is a dynamically stable state of ‘tolerated intergroup theft’, raising the question if corresponding patterns also exist in real intergroup conflicts. Finally, possible implications for theories of the co-evolution of bellicosity and altruism in humans are discussed. (shrink)

Contrary to chimpanzees and bonobos, humans display long-term exclusive relationships between males and females. Probably all human cultures have some kind of marriage system, apparently designed to protect these exclusive relationships and the resulting offspring in a potentially sexual competitive environment. Different hypotheses about the origin of human pair-bonds are compared and it is shown how they may refer to different phases of human evolution.

Jonathan Lear in Radical Hope tackles the idea of cultural devastation, in the specific case of the Crow Indians. What do we mean by “annihilation” of a culture? The moral point of view that he imagines as he reconstructs the eve and aftermath of this annihilation is not second personal, of obligation, but first personal, in the collective and singular, as told by the Crows, with Lear as “analyst.” Radical Hope is a study of representative character of a people—of virtue, (...) courage, resilience, and hope in the face of cultural collapse. The leading questions are shaped by ancient Greek ethics, but with a twist: On the brink of cultural death , what counts for us as good living and what is the nature of the virtues or excellences that constitute it? How might a leader, a phronimos , exemplify it? This puts it too narrowly. The questions, also, are Wittgensteinian: How does a nation go on, when the concepts and way of life it has lived by for centuries are no more? What does it mean to go on? What does it mean to stop when the marks of going on are no longer? (shrink)

The evolution of altruism in human societies has been intensively investigated in social and natural sciences. A widely acknowledged recent idea is the “parochial altruism model,” which suggests that inter- group hostility and intragroup altruism can coevolve through lethal intergroup conflicts. The current article critically examines this idea by reviewing research relevant to intergroup conflicts in human evolutionary history from evolutionary biology, psychology, cultural anthropology, and archaeology. After a brief intro- duction, section 2 illustrates the mathematical model of parochial altruism (...) and some critiques of the model and its interpretation, primarily from an evolutionary biology point of view. Section 3 delves into the archaeological evidence of prehistoric intergroup conflicts in the Japanese archipelago’s Jomon and Yayoi periods, Europe’s Mesolithic period, and North America’s Pacific period as counter examples of the paro- chial altruism model. In section 4, the ethnographies of intergroup relationships and conflicts reveal that intergroup relationships in many ethnic groups are not as simple as the assumption in the mathematical model of parochial altruism. In section 5, we outline psychological research on intergroup conflicts which suggest that intergroup hostility and ingroup altruism are not necessarily correlated. In conclusion, we argue that the assumption and parameter settings of the parochial altruism model are inconsistent with empirical data. (shrink)

Chapter 1 (To know in order to survive) & Chapter 2 (A critique of evolved reason) explain human knowledge and its limits from an evolutionary point of view. Chapter 3 (Captured in our Cockpits) explains the evolution of consciousness, using value driven decision theory. Chapter 4-6 (Chapter 4 Sociobiology, Chapter 5 Culture: the Human Arena), Chapter 6, Genes, Memes, and the Environment) show that to understand culture you have at least to deal with 4 levels: genes, brains, the environment, culture. (...) Chapter 7-8 (Why some apes became humans) give a model of human evolution in which Alexander's concept of 'ecological dominace' plays a crucial role. (shrink)

The ten original studies included in this Research Topic investigate selected assumptions and predictions of parochial altruism theory in detail. We, the editors, are convinced that their highly instructive findings will help researchers interested in parochial altruism, but also in intergroup psychology more generally, to gain a much more fine-grained understanding of the interplay of altruistic and spiteful motives in human decision making in the context of intergroup relations. The broad range of disciplines represented by the authors contributing to this (...) Research Topic and the variety of methods used in their studies are representative for the current interdisciplinary interest in parochial altruism. The most important insight that, in our view, can be derived from the works collected here is that human decision making in intergroup contexts is more complex than suggested by current theory. Thus, we hope that future theorizing on parochial altruism will be stimulated by the evidence gathered in this Research Topic. In this editorial, we briefly highlight central findings reported here, which, to us, appear most informative for prospective enhancements of parochial altruism theory. (shrink)

A common exhortation by conservationists suggests that we can solve ecological problems by returning to the attitudes of traditional societies: reverence for resources, and willingness to assume short-term individual costs for long-term, group-beneficial sustainable management. This paper uses the 186-society Standard Cross-Cultural Sample to examine resource attitudes and practices. Two main findings emerge: (1) resource practices are ecologically driven and do not appear to correlate with attitude (including sacred prohibition) and (2) the low ecological impact of many traditional societies results (...) not from conscious conservation efforts, but from various combinations of low population density, inefficient extraction technology, and lack of profitable markets for extracted resources. (shrink)

Several authors have claimed that mechanisms play a vital role in distinguishing between causation and mere correlation in the social sciences. Such claims are sometimes interpreted to mean that without mechanisms, causal inference in social science is impossible. The author agrees with critics of this proposition but explains how the account of how mechanisms aid causal inference can be interpreted in a way that does not depend on it. Nevertheless, he shows that this more charitable version of the account is (...) still unsuccessful as it stands. Consequently, he advances a proposal for shoring up the account, which is founded on the possibility of acquiring knowledge of social mechanisms by linking together norms or practices found in a society. Key Words: causality • social mechanisms • interpretation • anthropology. (shrink)

The wantok system in the Solomon Islands and the Melanesian countries more broadly, strongly links to the practices of group identity and belonging, reciprocity, and caring for one’s relatives. It is a term used to express patterns of relationships that link people in families, tribes, islands, provinces, nationality and even more superficially at greater Melanesian sub-regional aggregates. Various aspects of the wantok system are called different names by distinct language groups in Papua New Guinea, Solomon Islands and Vanuatu. Nevertheless, the (...) word wantok originates from the English words ‘one talk’, which literally means in Melanesian pidgin, speakers of the same language. (shrink)

Conspecific violence has been pervasive throughout evolutionary history. The current research tested the hypotheses that individuals implicitly categorize combative contexts (i.e., play fighting, status contests, warfare, and anti-exploitative violence) and use the associated contextual information to guide expectations of combative tactics. Using U.S. and non-U.S. samples, Study 1 demonstrated consistent classification of combative contexts from scenarios for which little information was given and predictable shifts in the acceptability of combative tactics across contexts. Whereas severe tactics (e.g., eye-gouging) were acceptable in (...) warfare and anti-exploitative violence, they were unacceptable in status contests and play fights. These results suggest the existence of implicit rules governing the contexts of combat. In Study 2, we explored the reputational consequences of violating these implicit rules. Results suggest that rule violators (e.g., those who use severe tactics in a status contest) are given less respect. These are the first studies to implicate specialized mechanisms for aggression that use contextual cues of violence to guide expectations and behavior. (shrink)

Applications of sexual selection theory to humans lead us to expect that because of mammalian sex differences in obligate parental investment there will be gender differences in fitness variances, and males will benefit more than females from multiple mates. Recent theoretical work in behavioral ecology suggests reality is more complex. In this paper, focused on humans, predictions are derived from conventional parental investment theory regarding expected outcomes associated with serial monogamy and are tested with new data from a postreproductive cohort (...) of men and women in a primarily horticultural population in western Tanzania (Pimbwe). Several predictions derived from the view that serial monogamy is a reproductive strategy from which males benefit are not supported. Furthermore, Pimbwe women are the primary beneficiaries of multiple marriages. The implications for applications of sexual selection theory to humans are discussed, in particular the fact that in some populations women lead sexual and reproductive lives that are very different from those derived from a simple Bateman-Trivers model. (shrink)

Sex- and age-specific rates of killing unrelated persons of one’s own sex were computed for Canada (1974–1983), England/Wales (1977–1986), Chicago (1965–1981), and Detroit (1972) from census information and data archives of all homicides known to police. Patterns in relation to sex and age were virtually identical among the four samples, although the rates varied enormously (from 3.7 per million citizens per annum in England/Wales to 216.3 in Detroit). Men’s marital status was related to the probability of committing a same-sex, nonrelative (...) homicide, but age effects remained conspicuous when married and unmarried men were distinguished.These findings and the treatment of age and sex effects by criminologists are discussed in the light of contemporary evolutionary psychological models of sex differences and life-span development. Same-sex homicides in which killer and victim are unrelated can be interpreted as an assay of competitive conflict. In every human society for which relevant information exists, men kill one another vastly more often than do women. Lethal interpersonal competition is especially prevalent among young men, which accords with many other aspects of life-span development in suggesting that sexual selection has maximized male competitive prowess and inclination in young adulthood. (shrink)

It has been suggested by some that the acquisition of symbolic capital in terms of honor, prestige, and power translates into an accumulation of material capital in terms of tangible belongings, and that on the basis of these goods high reproductive success may be achieved. However, data on completed fertility rates over more than one generation in so-called traditional societies have been rare. Ethnographic and demographic data presented here on the pastoral Bakkarwal of northern India largely corroborate the hypothesis concerning (...) the interdependence between the attainment of various cultural goals and differential reproduction rates and indicate that the numbers of (especially male) surviving offspring and siblings are crucial to a man’s position in society. (shrink)

The standard theories of cooperation in humans, which depend on repeated interaction and reputation effects among self-regarding agents, are inadequate. Strong reciprocity, a predisposition to participate in costly cooperation and the punishment, fosters cooperation where self-regarding behaviors fail. The effectiveness of socially coordinated punishment depends on individual motivations to participate, which are based on strong reciprocity motives. The relative infrequency of high-cost punishment is a result of the ubiquity of strong reciprocity, not its absence.

Economists and biologists have proposed a distinction between two mechanisms – “strong” and “weak” reciprocity – that may explain the evolution of human sociality. Weak reciprocity theorists emphasize the benefits of long-term cooperation and the use of low-cost strategies to deter free-riders. Strong reciprocity theorists, in contrast, claim that cooperation in social dilemma games can be sustained by costly punishment mechanisms, even in one-shot and finitely repeated games. To support this claim, they have generated a large body of evidence concerning (...) the willingness of experimental subjects to punish uncooperative free-riders at a cost to themselves. In this article, I distinguish between a “narrow” and a “wide” reading of the experimental evidence. Under the narrow reading, punishment experiments are just useful devices to measure psychological propensities in controlled laboratory conditions. Under the wide reading, they replicate a mechanism that supports cooperation also in “real-world” situations outside the laboratory. I argue that the wide interpretation must be tested using a combination of laboratory data and evidence about cooperation “in the wild.” In spite of some often-repeated claims, there is no evidence that cooperation in the small egalitarian societies studied by anthropologists is enforced by means of costly punishment. Moreover, studies by economic and social historians show that social dilemmas in the wild are typically solved by institutions that coordinate punishment, reduce its cost, and extend the horizon of cooperation. The lack of field evidence for costly punishment suggests important constraints about what forms of cooperation can or cannot be sustained by means of decentralised policing. (shrink)

Cruelty is the deliberate infliction of physical or psychological pain on other living creatures, sometimes indifferently, but often with delight. Though cruelty is an overwhelming presence in the world, there is no neurobiological or psychological explanation for its ubiquity and reward value. This target article attempts to provide such explanations by describing three stages in the development of cruelty. Stage 1 is the development of the predatory adaptation from the Palaeozoic to the ethology of predation in canids, felids, and primates. (...) Stage 2, through palaeontological and anthropological evidence, traces the emergence of the hunting adaptation in the Pliocene, its development in early hominids, and its emotional loading in surviving forager societies. This adaptation provides an explanation for the powerful emotions – high arousal and strong affect – evoked by the pain-blood-death complex. Stage 3 is the emergence of cruelty about 1.5 million years ago as a hominid behavioural repertoire that promoted fitness through the maintenance of personal and social power. The resulting cultural elaborations of cruelty in war, in sacrificial rites, and as entertainment are examined to show the historical and cross-cultural stability of the uses of cruelty for punishment, amusement, and social control. Effective violence prevention must begin with perpetrators, not victims. If the upstream approaches to violence prevention advocated by the public-health model are to be effective, psychologists must be able to provide violence prevention workers with a fine-grained understanding of perpetrator gratifications. This is a distasteful task that will compel researchers to interact with torturers and abusers, and to acknowledge that their gratifications are rooted in a common human past. It is nonetheless an essential step in developing effective strategies for the primary prevention of violence. Key Words: compassion; cruelty; entertainment industry; evolutionary psychology; intraspecific killing; pain; predation; punishment; torture; violence prevention. Correspondence:c1 Correspondence to: West Hill House, 6 Swains Lane, Highgate, London N6 6QS, United Kingdom. (shrink)

MOST MODERN PEOPLE think it is obvious why people become modern. For them, a more interesting and important puzzle is why some people fail to embrace modern ideas. Why do people in traditional societies often seem unable or unwilling to aspire to a better life for themselves and their children? Why do they fail to see the benefi ts of education, equal rights, democracy, and a rational approach to decisionmaking? What is the glue that makes them adhere to superstition, religion, (...) and obligations to family and tribe even if it means accepting a life of insecurity and poverty? The “kin infl uence hypothesis” (Newson et al. 2005) suggests an explanation both for why people become modern and for why modern ideas are often slow to be accepted by a population. The hypothesis is based on the understanding gained by social-psychological research of how cultural norms change. It takes a Darwinian approach to explaining human behavior and recognizes that much of the cultural change associated with modernization is a progressive abandonment of values and norms that encourage people to pursue what evolutionary theorists refer to as “reproductive success.”1 The kin infl uence hypothesis proposes that the cascade of cultural changes associated with modernization is the result of the momentous change in the human social environment that occurs early in economic development. For most of human evolutionary history, the norms of all cultures must have prescribed behavior that, on balance, enhanced the genetic fi tness of their members. If this were not the case, then, as Lumsden and Wilson (1981) and Alexander (1979) rightly pointed out, evolutionary biologists would be unable to explain how humans evolved the uniquely human capacity for learning and imitation that makes culture possible. Nor could we explain how an African ape came to be the world’s dominant organism. With economic development, however, people begin to abandon the beliefs and values that encourage fi tness-enhancing behavior.. (shrink)

L’objectif de cet article est double. Premièrement, nous proposons une définition économique du mal. Un agent accomplit une action économique malfaisante s’il blesse (ou incite à blesser) intentionnellement, matériellement, un autre agent, s’il subit une perte matérielle à la suite de cette action et si la possibilité d’un choix plus gratifiant pour lui existait. Deuxièmement, nous discutons de la manière dont nous pouvons catégoriser différentes théories du mal économique et différentes actions économiquement malfaisantes sur la base d’une analyse de la (...) relation entre l’agent malfaisant et l’autre blessé. Notre article met en lumière qu’un type particulier de mal économique n’a pas encore reçu l’attention requise. Ce type de mal économique se caractérise par une relation spécifique entre l’agent et l’autre : l’agent ne se soucie de l’autre que dans la mesure où le gain matériel de l’autre est concerné – et seulement dans la mesure où il s’assure que ce dernier sera négativement impacté par son action. L’article cite également des preuves de tels comportements. JEL Codes : D74, P16, P48, Z13. (shrink)

Evolutionary models of human cooperation are increasingly emphasizing the role of reputation and the requisite truthful “gossiping” about reputation-relevant behavior. If resources were allocated among individuals according to their reputations, competition for resources via competition for “good” reputations would have created incentives for exaggerated or deceptive gossip about oneself and one’s competitors in ancestral societies. Correspondingly, humans should have psychological adaptations to assess gossip veracity. Using social psychological methods, we explored cues of gossip veracity in four experiments. We found that (...) simple reiteration increased gossip veracity, but only for those who found the gossip relatively uninteresting. Multiple sources of gossip increased its veracity, as did the independence of those sources. Information that suggested alternative, benign interpretations of gossip decreased its veracity. Competition between a gossiper and her target decreased gossip veracity. These results provide preliminary evidence for psychological adaptations for assessing gossip veracity, mechanisms that might be used to assess veracity in other domains involving social exchange of information. (shrink)

The pioneering ideas of Glenn D. Paige for a paradigm shift from killing to nonkilling are highlighted. The relevance of anthropology for this paradigm is advanced. The accumulating scientific evidence proves that nonviolent and peaceful societies not only exist, but are actually the norm throughout human prehistory and history. This scientific fact is elucidated through a historical inventory of the most important documentation. Ethnographic cases are summarized of the Semai as a nonviolent society, the transition from killing to nonkilling of (...) the Waorani, and the critiques of the representation of the Yanomami as a killing society. Several of the most important cross-cultural studies are discussed. The assertions of some of the most vocal opponents to this paradigm are refuted. The systemic cultural and ideological bias privileging violence and war over nonviolence and peace is documented. (shrink)

In this paper we present two compatible hypotheses to explain interest in celebrity gossip. The Learning Hypothesis explains interest in celebrity gossip as a by-product of an evolved mechanism useful for acquiring fitness-relevant survival information. The Parasocial Hypothesis sees celebrity gossip as a diversion of this mechanism, which leads individuals to misperceive celebrities as people who are part of their social network. Using two preliminary studies, we tested our predictions. In a survey with 838 respondents and in-depth interviews with 103 (...) individuals, we investigated how interest in celebrity gossip was related to several dimensions of the participants’ social lives. In support of the Learning Hypothesis, age proved to be a strong predictor of interest in celebrities. In partial support of the Parasocial Hypothesis, media exposure, but not social isolation, was a strong predictor of interest in celebrities. The preliminary results support both theories, indicate that across our life span celebrities move from being teachers to being friends, and open up a list of future research opportunities. (shrink)

This paper proposes a model of human uniqueness based on an unusual distinction between two contrasted kinds of political competition and political status: (1) antagonistic competition, in quest of dominance (antagonistic status), a zero-sum, self-limiting game whose stake—who takes what, when, how—summarizes a classical definition of politics (Lasswell 1936), and (2) synergistic competition, in quest of merit (synergistic status), a positive-sum, self-reinforcing game whose stake becomes “who brings what to a team’s common good.” In this view, Rawls’s (1971) famous virtual (...) “veil of ignorance” mainly conceals politics’ antagonistic stakes so as to devise the principles of a just, egalitarian society, yet without providing any means to enforce these ideals (Sen 2009). Instead, this paper proposes that human uniqueness flourished under a real “adapted veil of ignorance” concealing the steady inflation of synergistic politics which resulted from early humans’ sturdy egalitarianism. This proposition divides into four parts: (1) early humans first stumbled on a purely cultural means to enforce a unique kind of within-team antagonistic equality—dyadic balanced deterrence thanks to handheld weapons (Chapais 2008); (2) this cultural innovation is thus closely tied to humans’ darkest side, but it also launched the cumulative evolution of humans’ brightest qualities—egalitarian team synergy and solidarity, together with the associated synergistic intelligence, culture, and communications; (3) runaway synergistic competition for differential merit among antagonistically equal obligate teammates is the single politically selective mechanism behind the cumulative evolution of all these brighter qualities, but numerous factors to be clarified here conceal this mighty evolutionary driver; (4) this veil of ignorance persists today, which explains why humans’ unique prosocial capacities are still not clearly understood by science. The purpose of this paper is to start lifting this now-ill-adapted veil of ignorance, thus uncovering the tight functional relations between egalitarian team solidarity and the evolution of human uniqueness. (shrink)

When the social sciences parted company from evolutionary biology almost exactly a century ago, they did so at a time when evolutionary biology was still very much in its infancy and many key issues were unresolved. As a result, the social sciences took away with them an understanding of evolution that was in fact based on 18th- rather than 19th-century biology. I argue that contemporary evolutionary thinking has much more to offer the social sciences than most people have assumed. Contemporary (...) evolutionary research on human behaviour focuses on two main issues at the micro-social scale: understanding the trade-offs in individual decision-making and understanding the cognitive constraints that limit flexibility of decisions. I offer examples of both of these approaches. Finally, I consider the broader question of the macro-social scale. (shrink)

In this commentary, I review diverse lines of research conducted at both the macrosocial and microbehavioral level that dispute the view that cruelty is inherently gratifying. Expressions of pain and suffering typically inhibit rather than reinforce cruel conduct in humans. With regard to functional value, cruelty has diverse personal and social effects, not just the alluring benefits attributed to it.

Examining the costs and motivations of warfare is key to conundrums concerning the relevance of this troubling phenomenon to the evolution of social attachment and cooperation, particularly during adolescence and young adulthood—the developmental time period during which many participants are first recruited for warfare. The study focuses on Samburu, a pastoralist society of approximately 200,000 people occupying northern Kenya’s semi-arid and arid lands, asking what role the emotionally sensitized, peer-driven adolescent life stage may have played in the cultural and genetic (...) coevolution of coalitional lethal aggression. Research in small-scale societies provides unparalleled opportunities for sharply defined variables, particularly in age generation societies in which all young men are initiated into “warriorhood.” Proposing an epigenetic and component behavior approach, we examine whether raiding activities such as number of raids, killing, and sparing enemy lives associate with DNA methylation in two candidate genes: MAOA, linked to mood and arousal, and NR3C1, linked to stress and immune response. We report statistically significant associations between the epigenetic variables and the combat variables of overall raiding activity and reportedly showing mercy to enemies. In contrast, epigenetic variables did not associate with post-traumatic stress disorder symptom scores, and the only combat variable associated with PTSD was losing one’s own livestock in a raid. These findings raise important questions concerning the mechanisms driving warfare’s paradoxical mix of violent and altruistic behaviors. (shrink)

The present research examined how a preference for influencing the mate choice of one’s offspring is associated with opposition to out-group mating among parents from three ethnic groups in the Mexican state of Oaxaca: mestizos (people of mixed descent, n = 103), indigenous Mixtecs (n = 65), and blacks (n = 35). Nearly all of the men in this study were farmworkers or fishermen. Overall, the level of preferred parental influence on mate choice was higher than in Western populations, but (...) lower than in Asian populations. Only among the Mixtecs were fathers more in favor of parental influence on the mate choice of children than mothers were. As predicted, opposition to out-group mating was an important predictor of preferred parental influence on mate choice, more so among fathers than among mothers, especially in the mestizo group—the group with the highest status. In addition, women, and especially mestizo women, expressed more opposition to out-group mating than men did. (shrink)

Sports are an excellent venue for demonstrating evolutionary principles to audiences not familiar with academic research. Team sports and sports fandom feature dynamics of in-group loyalty and intergroup competition, influenced by our evolved coalitional psychology. We predicted that reactions to expressions signaling mutual team/group allegiance would vary as a function of the territorial context. Reactions should become more prevalent, positive, and enthusiastic as one moves from the home territory to a contested area, and from a contested area to a rival’s (...) territory during active rival engagement. We also predicted that men would be more responsive than women based on sex differences in evolved coalitional psychology. The research team visited public places immediately prior to 2016–2017 collegiate football and basketball games. A male research confederate wore a sweatshirt displaying the logo of one of the competing university teams and vocalized the team’s most popular slogan when he saw a fan displaying similar logos. Observers followed 5 m behind, recording reactions and response positivity/enthusiasm. Reaction tone was most positive in the rival territory, least positive in the home territory, and intermediate in the periphery and contested territory. Rates of “no reaction” were lowest in the rival territory but were highest in the periphery. Men had higher reaction rates and more positive and enthusiastic reaction tones than women. Reactions generally followed predictions based on expected signal value. This project provides evidence that coalitional psychology influences dynamics related to university sports team rivalries and that context matters for expressions of alliance. (shrink)

The cultural norms of traditional societies encourage behavior that is consistent with maximizing reproductive success but those of modern post-demographic transition societies do not. Newson et al (2005) proposed that this might be because interaction between kin is relatively less frequent in modern social networks. Assuming that people’s evaluations of reproductive decisions are influenced by a desire to increase their inclusive fitness, they will be inclined to prefer their kin to make fitness-enhancing choices. Such a preference will encourage the emergence (...) of pronatal cultural norms if social networks are dense with kin. Less pronatal norms will emerge if contact between kin makes up a small proportion of social interactions. This article reports evidence based on role-play studies that supports the assumption of the kin influence hypothesis that evaluations of reproductive decisions are influenced by a desire to increase inclusive fitness. It also presents a cultural evolutionary model demonstrating the long-term effect of declining kin interaction if people are more likely to encourage fitness-enhancing choices when interacting with their kin than with nonrelatives. D 2007 Elsevier Inc. All rights reserved. (shrink)

This study tested four theoretical models of leadership with data from the ethnographic record. The first was a game-theoretical model of leadership in collective actions, in which followers prefer and reward a leader who monitors and sanctions free-riders as group size increases. The second was the dominance model, in which dominant leaders threaten followers with physical or social harm. The third, the prestige model, suggests leaders with valued skills and expertise are chosen by followers who strive to emulate them. The (...) fourth proposes that in small-scale, kin-based societies, men with high neural capital are best able to achieve and maintain positions of social influence (e.g., as headmen) and thereby often become polygynous and have more offspring than other men, which positively selects for greater neural capital. Using multiple search strategies we identified more than 1000 texts relevant to leadership in the Probability Sample of 60 cultures from the Human Relations Area Files (HRAF). We operationalized the model with variables and then coded all retrieved text records on the presence or absence of evidence for each of these 24 variables. We found mixed support for the collective action model, broad support for components of the prestige leadership style and the importance of neural capital and polygyny among leaders, but more limited support for the dominance leadership style. We found little evidence, however, of emulation of, or prestige-biased learning toward, leaders. We found that improving collective actions, having expertise, providing counsel, and being respected, having high neural capital, and being polygynous are common properties of leaders, which warrants a synthesis of the collective action, prestige, and neural capital and reproductive skew models. We sketch one such synthesis involving high-quality decision-making and other computational services. (shrink)

Reciprocity theory (RT) and costly signaling theory (CST) provide different explanations for the high status of pro-community altruists: RT proposes that altruists are positively and negatively sanctioned by others, whereas CST proposes that altruists are attractive to others. Only RT, however, is beset by first- and higher-order free rider problems, which must be solved in order for RT to explain status allocations. In this paper, several solutions to RT’s free rider problems are proposed, and data about status allocations to Ecuadorian (...) Shuar pro-community altruists are analyzed in light of RT and CST. These data confirm that perceived pro-community altruists are indeed high status and suggest that (1) community residents skillfully monitor the altruism of coresidents, (2) residents who engage in opportunities to broadcast desirable qualities are high status only to the extent that they are considered altruistic, and (3) individuals who sanction coresidents based on coresidents’ contributions to the community are themselves relatively high status. To a greater extent than CST, RT straightforwardly predicts all of these results. (shrink)

Human coalitions frequently persist through multiple, overlapping membership generations, requiring new members to cooperate and coordinate with veteran members. Does the mind contain psychological adaptations for interacting within these intergenerational coalitions? In this paper, we examine whether the mind spontaneously treats newcomers as a motivationally privileged category. Newcomers—though capable of benefiting coalitions—may also impose considerable costs (e.g., they may free ride on other members, they may be poor at completing group tasks). In three experiments we show (1) that the mind (...) categorizes coalition members by tenure, including newcomers; (2) that tenure categorization persists in the presence of orthogonal and salient social dimensions; and (3) that newcomers elicit a pattern of impressions consistent with their probable ancestral costs. These results provide preliminary evidence for a specialized component of human coalitional psychology: an evolved concept of newcomer. (shrink)

This monograph-length contribution to the Common Knowledge symposium “Peace by Other Means” reviews and assesses the state of ethnographic and political scholarship concerning how nonstate, tribal societies deal with peacemaking and peacekeeping. A central argument is that the condition among nonstate societies was and is neither one of permanent war nor one of permanent peace but one of permanent peacelessness. Nonstate societies recognize the danger of warfare and take measures to reduce its likelihood, or at least try to mitigate its (...) destructiveness. This article treats the politics, strategies, and practices of peacemaking in tribal societies throughout the world, as well as the full spectrum of attempts at war mitigation. (shrink)

Coalitions and alliances are core aspects of human behavior. All societies recognize alliances among communities, usually based in part on kinship and marriage. Aggression between groups is ubiquitous, often deadly, fueled by revenge, and can have devastating effects on general human welfare. Given its significance, it is surprising how little we know about the neurobiological and hormonal mechanisms that underpin human coalitionary behavior. Here we first briefly review a model of human coalitionary behavior based on a process of runaway social (...) selection. We then present several exploratory analyses of neuroendocrine responses to coalitionary social events in a rural Dominican community, with the objective of understanding differences between in-group and out-group competition in adult and adolescent males. Our analyses indicate: (1) adult and adolescent males do not elevate testosterone when they defeat their friends, but they do elevate testosterone when they defeat outsiders; (2) pre-competition testosterone and cortisol levels are negatively associated with strength of coalitionary ties; and (3) adult males usually elevate testosterone when interacting with adult women who are potential mates, but in a striking reversal, they have lower testosterone if the woman is a conjugal partner of a close friend. These naturalistic studies hint that reciprocity, dampening of aggression, and competition among friends and allies may be biologically embedded in unique ways among humans. (shrink)

This article is divided into two main sections. The first discusses “Female Inheritance and the Male Retention Hypothesis.” Permanent groups (groups with no inherent limit on group longevity) exist in several species because over generations members share important interests. Considering the association between cooperation and degree of relatedness, it seems to follow that a collective interest is more likely to be achieved when members show a higher degree of relatedness. I argue that if membership is inherited by only one sex, (...) and this is the female sex, this results in a higher degree of relatedness between group members than when membership is inherited by both sexes, or by males only. Indeed, this is found in the overwhelming majority of species of insects, fish, birds, and mammals living in permanent groups. The (few) exceptions to the rule are briefly discussed. Humans are of special interest because human preindustrial societies tend to show either male or female inheritance. The second section asks, “Do Moralizing Gods Raise Paternity Confidence?” Since males inherit valuable membership in patrilocal/lineal societies, they are expected to be more concerned about the probability of paternity than males in matrilocal/lineal societies. Moral rules, and specifically belief in moralizing gods, are expected to reflect this difference. An analysis of cross-cultural data of preindustrial societies does not refute the hypothesis that moralizing gods are more often found in patrilocal/lineal societies, nor is this hypothesis unambiguously supported. (shrink)