Parochial altruism in humans

Abstract

Social norms and the associated altruistic behaviours are decisive for the evolution of human cooperation and the maintenance of social order, and they affect family life, politics and economic interactions. However, as altruistic norm compliance and norm enforcement often emerge in the context of inter-group conflicts, they are likely to be shaped by parochialism--a preference for favouring the members of one's ethnic, racial or language group. We have conducted punishment experiments, which allow 'impartial' observers to punish norm violators, with indigenous groups in Papua New Guinea. Here we show that these experiments confirm the prediction of parochialism. We found that punishers protect ingroup victims--who suffer from a norm violation--much more than they do outgroup victims, regardless of the norm violator's group affiliation. Norm violators also expect that punishers will be lenient if the latter belong to their social group. As a consequence, norm violations occur more often if the punisher and the norm violator belong to the same group. Our results are puzzling for evolutionary multi-level selection theories based on selective group extinction as well as for theories of individual selection; they also indicate the need to explicitly examine the interactions between individuals stemming from different groups in evolutionary models.

The mentalizing network orchestrates the impact of parochial altruism on social norm enforcement

“…Experimental evidence from laboratory [Brewer, 1979;Chen and Li, 2009;Kinzler et al, 2007;Koopmans and Rebers, 2009;Tajfel and Turner, 1979;Tajfel et al, 1971] and field studies [Bernhard et al, 2006;Fehr et al, 2008;Goette et al, 2006] demonstrates that parochial altruism strongly shapes the compliance and enforcement of social norms. Parochial altruism constitutes a persuasive psychological phenomenon which is qualified by a preference for altruistic behavior towards the members of one's ethnic, racial, or any other social group, combined with a tendency for indifference, mistrust, or even hostility toward outgroup members [Brewer, 1999;Hewstone et al, 2002].…”

“…Parochial altruism constitutes a persuasive psychological phenomenon which is qualified by a preference for altruistic behavior towards the members of one's ethnic, racial, or any other social group, combined with a tendency for indifference, mistrust, or even hostility toward outgroup members [Brewer, 1999;Hewstone et al, 2002]. For example, a recent third-party punishment experiment in Papua New Guinea revealed strong favoritism toward a subject's own linguistic group in giving to others, and significantly greater punishment of individuals from another linguistic group (in comparison to those from the subject's own group) who committed a norm violation toward the subject's ingroup members [Bernhard et al, 2006]. The importance of parochial altruism for the understanding of human society is corroborated by recent theoretical and experimental research that has closely tied outgroup hostility to the evolution of human prosociality within groups [Boyd et al, 2003;Choi and Bowles, 2007] and prosociality within groups (ingroup favoritism) to the evolution of cultural groups [Efferson et al, 2008].…”

“…By using a third-party punishment paradigm [Fehr and Fischbacher, 2004b] with manipulation of group membership (in/outgroup) [Bernhard et al, 2006;Goette et al, 2006], the involvement of real monetary stakes, and the requirement to curb immediate self-interests in order to enforce a social norm, this study is the first to uncover the neural circuitry of parochial altruism and its impact on the enforcement of social norms. For that purpose, we exploited the fact that individuals are randomly assigned to real social groups (platoons) during a four-week phase of officer training in the Swiss Army.…”

“…Based on the discussed behavioral literature [Bernhard et al, 2006;Fehr and Fischbacher 2004b;Goette et al, 2006], we expect third-parties to show a parochial punishment pattern, qualified by a particular strong impact of group membership on punishment decisions in the DC condition, when Player A defects and Player B cooperates. In detail, we hypothesize that outgroup members who defect against cooperating ingroup members are punished much more severely than ingroup members who commit the same norm violation-a hypothesis the behavioral analyses strongly confirm (see results section for details).…”

Not on my team: Medial prefrontal cortex responses to ingroup fusion and unfair monetary divisions

“…Such reactions to unfairness develop early, with children as young as eighteen months old reacting negatively to unequal distributions of rewarding stimuli (Sloane, Baillargeon, & Premack, 2012). However, our reactions to fair and unfair behaviors are influenced by the social identities of parties to an interaction (Bernhard, Fischbacher, & Fehr, 2006), but whether the effects of social identity on second‐party punishment are magnified by salient group alignments is less well‐understood.…”