Human Nature-An Interdisciplinary Biosocial Perspective最新文献

It has been theorized that the contagion of behaviors may be related to social cognitive abilities, but empirical findings are inconsistent. We recorded young adults' behavioral expression of contagious yawning and contagious smiling to video stimuli and employed a multi-method assessment of sociocognitive abilities including self-reported internal experience of emotional contagion, self-reported trait empathy, accuracy on a theory of mind task, and observed helping behavior. Results revealed that contagious yawners reported increases in tiredness from pre- to post-video stimuli exposure, providing support for the internal experience of emotional contagion, and were more likely to provide help to the experimenter relative to non-contagious yawners. Contagious smilers showed stably high levels of self-reported happiness from pre- to post-video exposure, were more likely to provide help to the experimenter, and had increased accuracy on a theory of mind task relative to non-contagious smilers. There were no differences in self-reported trait empathy for contagious versus non-contagious yawners or smilers. Contagious yawning may be related to some basic (i.e., emotional contagion) and advanced (i.e., helping behavior) sociocognitive processes, whereas contagious smiling is related to some advanced sociocognitive processes (i.e., theory of mind and helping behavior).

Raymond Kelly's widely cited Warless Societies and the Origin of War (University of Michigan Press, 2000) seeks to explain the origins of two central signatures of human society: war and segmented-i.e., multilevel-societies. Both, he argues, arose with the emergence of a social-substitutability principle, a rule that establishes a collective identity among a set of individuals such that any one member becomes equivalent to, and responsible for the actions of, the others. This principle emerged during the Holocene, when population increase gave rise to the first lethal ambushes. By its nature, ambush obscures attackers' identities. Those attempting to retaliate for the ambush were therefore obliged to target members of the ambushers' group indiscriminately-i.e., based on a social-substitutability principle. Kelly's proposals draw welcome attention to a widespread, deeply influential, and unsettling human behavior, the disposition to hold everyone in a group culpable for the actions of a few, a proclivity that all too often results in mass slaughter. His general argument, however, is logically and empirically deficient, and cross-cultural evidence on ambush in contact-era New Guinea undermines his anonymity-of-ambush hypothesis. What then accounts for war and multilevel society? The New Guinea evidence strongly supports a contention that social-substitutability behavior arose not from offensive military action (i.e., ambush) but from the defensive military response to ambush. These findings render the social-substitutability argument's unconventional definition of war superfluous, undermine its chronology for the emergence of war, and underwrite an alternative scenario for the origins of multilevel, segmented society.

"Culture of honor" means that individuals deter others by signaling their commitment to violent retaliation. We develop a multilevel explanation of cross-level interdependence of honor and violence. According to our concept of system-level honor, a social system is loaded with deterrence signaling if culture of honor is highly prevalent in the system. In line with the Smith and Price (1973, in Nature, https://www.nature.com/articles/246015a0 ) model, we argue that high system-level honor discourages Prober-Retaliator behavior: some individuals might tend to challenge others they assume to be inferior to increase their own reputation. Both individual culture of honor and system-level honor contribute to an increase in violence (H1; H2). However, as system-level honor and deterrence become more prevalent, the impact of individual honor diminishes because engaging in violent behavior becomes increasingly expensive within such a system (H3). As a second contextual effect, inequality in culture of honor should therefore increase violent behavior because it encourages Prober-Retaliator behavior (H4). We analyze the effect of culture of honor on school violence among 15-year-old adolescents. Disentangling the micro- and context-level effects of culture of honor on violent behavior in a multilevel analysis framework allows the estimation of a cross-level interaction using a large data set from more than 25,000 adolescents in more than 1,300 schoolroom contexts. Results are in line with our H3, but not with H4. Model-based predictions show that the deterrent effect must be unrealistically high to generate an equilibrium of average violence.

Focusing on clothing and adornment (dress), this worldwide cross-cultural comparison asks why people in some societies appear to dress in uniform or standardized ways, whereas in other societies individuals display considerable variability in dress. The broader research question is why some societies have more within-group variation than others. Hypotheses are tested on 80 societies drawn from the Standard Cross-Cultural Sample (SCCS). The central hypotheses consider the impact of general societal tightness or looseness, degree of egalitarianism as well as other aspects of societal complexity, and the role of resource stress on dress standardization. Exploratory methods identify four latent constructs of dress from newly coded variables, one latent construct for tightness/looseness, and one latent construct for resource stress. As expected, (1) increased societal tightness was positively related to increased standardization and rules regarding dress and (2) increased resource stress is generally related to more standardization of dress and rules regarding adornment. However, contrary to theoretical expectations, the predictors of tightness-looseness differ from the predictors of dress. Most importantly, resource stress negatively predicts tightness but positively predicts three of the latent dress constructs. The relationship between dress standardization and societal complexity may be curvilinear, with mid-range societies having more standardization. Although some of the theorized relationships are supported (including that standardization of dress is predicted by societal tightness and more resource stress), at the end of paper we discuss some puzzling findings, speculate about possible explanations, and suggest further lines of research.

The evolutionary origins of deception and its functional role in our species is a major focus of research in the science of human origins. Several hypotheses have been proposed for its evolution, often packaged under either the Social Brain Hypothesis, which emphasizes the role that the evolution of our social systems may have played in scaffolding our cognitive traits, and the Foraging Brain Hypothesis, which emphasizes how changes in the human dietary niche were met with subsequent changes in cognition to facilitate foraging of difficult-to-acquire foods. Despite substantive overlap, these hypotheses are often presented as competing schools of thought, and there have been few explicitly proposed theoretical links unifying the two. Utilizing cross-cultural data gathered from the Human Relations Area Files (HRAF), we identify numerous (n = 357) examples of the application of deception toward prey across 145 cultures. By comparing similar behaviors in nonhuman animals that utilize a hunting strategy known as aggressive mimicry, we suggest a potential pathway through which the evolution of deception may have taken place. Rather than deception evolving as a tactic for deceiving conspecifics, we suggest social applications of deception in humans could have evolved from an original context of directing these behaviors toward prey. We discuss this framework with regard to the evolution of other mental traits, including language, Theory of Mind, and empathy.

The amygdala is a hub in brain networks that supports social life and fear processing. Compared with other apes, humans have a relatively larger lateral nucleus of the amygdala, which is consistent with both the self-domestication and the cooperative breeding hypotheses of human evolution. Here, we take a comparative approach to the evolutionary origin of the relatively larger lateral amygdala nucleus in humans. We carry out phylogenetic analysis on a sample of 17 mammalian species for which we acquired single amygdala nuclei volumetric data. Our results indicate that there has been convergent evolution toward larger lateral amygdala nuclei in both domesticated and cooperatively breeding mammals. These results suggest that changes in processing fearful stimuli to reduce fear-induced aggression, which are necessary for domesticated and cooperatively breeding species alike, tap into the same neurobiological proximate mechanism. However, humans show changes not only in processing fearful stimuli but also in proactive prosociality. Since cooperative breeding, but not domestication, is also associated with increased proactive prosociality, a prominent role of the former during human evolution is more parsimonious, whereas self-domestication may have been involved as an additional stepping stone.

Population dynamics form a crucial component of human narratives in the past. Population responses and adaptations not only tell us about the human past but also offer insights into the present and future. Though an area of substantial interest, it is also one of often limited evidence. As such, traditional techniques from demography and anthropology must be adapted considerably to accommodate the available archaeological and ethnohistoric data and an appropriate inferential framework must be applied. In this article, I propose a ground-up, multidisciplinary approach to the study of past population dynamics. Specifically, I develop an empirically informed path diagram based on modern fertility interactions and sources of past environmental, sociocultural, and biological evidence to guide high-resolution case studies. The proposed approach is dynamic and can evolve in response to data inputs as case studies are undertaken. In application, this approach will create new knowledge of past population processes which can greatly enhance our presently limited knowledge of high-frequency, small-scale demographic fluctuations, as well as contribute to our broader understanding of significant population disturbances and change throughout human history.

Alloparenting, wherein people provide care to children who are not their biological offspring, is a key aspect of human child-rearing. In the Pacific, many children are adopted or fostered by custodial alloparents even when both biological parents are still alive. From a behavioral ecology perspective, such behaviors are puzzling: why parent someone else's child at your expense? Furthermore, little is known about how these arrangements are made in Pacific Islander societies today, who provides care, and what kinds of outcomes fostered children experience. A better understanding of these proximate factors may help reveal the ultimate drivers behind custodial alloparenting. Here, we report findings from a survey carried out with the caregivers of 282 children in rural areas of Vanuatu, an island nation in Melanesia. Most fostered and adopted children lived with relatives such as aunts, uncles, and grandparents (87.5%) rather than unrelated caregivers, with a strong preference for maternal kin. The most common reasons for these arrangements were that the parents had separated (16.7%), were engaging in labor migration (27.1%), or a combination of both (27.1%). Results for investment in children's education and their educational outcomes were mixed, although children removed from crisis situations did more poorly than children removed for aspirational reasons. Our findings suggest that custodial alloparenting helps families adapt to socioeconomic transitions and changing marriage practices. Outcomes may depend on a range of factors, such as the reason children were transferred out of the natal home to begin with.

This research provides evidence regarding the causal effect of group conformity on task performance in stable and variable environments. Drawing on studies in cultural evolution, social learning, and social psychology, we experimentally tested the hypotheses that conformity improves group performance in a stable environment (H1) and decreases performance (by hindering adaptability) in a temporally variable environment (H2). We compare the performance of individuals, low conformity groups, and high conformity groups in a four-arm randomized lab experiment (N = 240). High conformity was manipulated by rewarding agreement with the group's majority and imposing a cost on disagreement. The monetary implications of conformity impaired performance in a variable environment but did not have a significant effect on performance in the stable environment. Intragroup individual-level analyses provide insights into the mechanisms that account for the group-level results by showing that lower conformity in groups facilitates efficient adaptability in the use of social information.

Whereas many evolutionary models emphasize within-group cooperation or between-group competition in explaining human large-scale cooperation, recent work highlights a critical role for intergroup cooperation in human adaptation. Here we investigate intergroup cooperation in the domain of shotgun hunting in northern Republic of the Congo. In the Congo Basin broadly, forest foragers maintain relationships with neighboring farmers based on systems of exchange regulated by norms and institutions such as fictive kinship. In this study, we examine how relationships between Yambe farmers and BaYaka foragers support stable intergroup cooperation in the domain of shotgun hunting. In the study village, shotgun hunting is based on a specialization-based exchange wherein Yambe farmers contribute shotguns and access to markets to buy cartridges and sell meat while BaYaka foragers contribute their specialized forest knowledge and skill. To understand how costs and benefits are distributed, we conducted structured interviews with 77 BaYaka hunters and 15 Yambe gun owners and accompanied hunters on nine hunting trips. We found that hunts are organized in a conventional manner within a fictive kinship structure, consistent with the presence of intercultural mechanisms to stabilize cooperation. However, because bushmeat demand is high, gun owners can gain significant cash profit, while compensating hunters only with cigarettes, alcohol, and a traditional hunter's portion of meat. To level payoffs, hunters strategically hide kills or cartridges from gun owners to feed their own families. Our results illustrate how each group prioritizes different currencies (e.g., cash, meat, family, intergroup relations) and provide insights into how intergroup cooperation is stabilized in this setting. The example of this long-standing intergroup cooperative system is discussed in terms of its contemporary entwinement with logging, the bushmeat trade, and growing market intersection.