Oxytocin, but not vasopressin, increases both parochial and universal altruism.

In today's increasingly interconnected world, deciding with whom and at what level to cooperate becomes a matter of increasing importance as societies become more globalized and large-scale cooperation becomes a viable means of addressing global issues. This tension can play out via competition between local (e.g. within a group) and global (e.g., between groups) interests. Despite research highlighting factors influencing cooperation in such multi-layered situations, their biological basis is not well understood. In a double-blind placebo controlled study, we investigated the influence of intranasally administered oxytocin and arginine vasopressin on cooperative behavior at local and global levels. We find that oxytocin causes an increase in both the willingness to cooperate and the expectation that others will cooperate at both levels. In contrast, participants receiving vasopressin did not differ from those receiving placebo in their cooperative behavior. Our results highlight the selective role of oxytocin in intergroup cooperative behavior.

AVPR1A variant associated with preschoolers' lower altruistic behavior.

The genetic origins of altruism, defined here as a costly act aimed to benefit non-kin individuals, have not been examined in young children. However, previous findings concerning adults pointed at the arginine vasopressin receptor 1A (AVPR1A) gene as a possible candidate. AVPR1A has been associated with a range of behaviors including aggressive, affiliative and altruistic phenotypes, and recently a specific allele (327 bp) of one of its promoter region polymorphisms (RS3) has been singled out in particular. We modeled altruistic behavior in preschoolers using a laboratory-based economic paradigm, a modified dictator game (DG), and tested for association between DG allocations and the RS3 "target allele." Using both population and family-based analyses we show a significant link between lower allocations and the RS3 "target allele," associating it, for the first time, with a lower proclivity toward altruistic behavior in children. This finding helps further the understanding of the intricate mechanisms underlying early altruistic behavior.

The oxytocin receptor (OXTR) contributes to prosocial fund allocations in the dictator game and the social value orientations task.

BACKGROUND: Economic games observe social decision making in the laboratory that involves real money payoffs. Previously we have shown that allocation of funds in the Dictator Game (DG), a paradigm that illustrates costly altruistic behavior, is partially determined by promoter-region repeat region variants in the arginine vasopressin 1a receptor gene (AVPR1a). In the current investigation, the gene encoding the related oxytocin receptor (OXTR) was tested for association with the DG and a related paradigm, the Social Values Orientation (SVO) task. METHODOLOGY/PRINCIPAL FINDINGS: Association (101 male and 102 female students) using a robust-family based test between 15 single tagging SNPs (htSNPs) across the OXTR was demonstrated with both the DG and SVO. Three htSNPs across the gene region showed significant association with both of the two games. The most significant association was observed with rs1042778 (p = 0.001). Haplotype analysis also showed significant associations for both DG and SVO. Following permutation test adjustment, significance was observed for 2-5 locus haplotypes (p<0.05). A second sample of 98 female subjects was subsequently and independently recruited to play the dictator game and was genotyped for the three significant SNPs found in the first sample. The rs1042778 SNP was shown to be significant for the second sample as well (p = 0.004, Fisher's exact test). CONCLUSIONS: The demonstration that genetic polymorphisms for the OXTR are associated with human prosocial decision making converges with a large body of animal research showing that oxytocin is an important social hormone across vertebrates including Homo sapiens. Individual differences in prosocial behavior have been shown by twin studies to have a substantial genetic basis and the current investigation demonstrates that common variants in the oxytocin receptor gene, an important element of mammalian social circuitry, underlie such individual differences.

Molecular genetic studies of the arginine vasopressin 1a receptor (AVPR1a) and the oxytocin receptor (OXTR) in human behaviour: from autism to altruism with some notes in between.

Converging evidence from both human and animal studies has highlighted the pervasive role of two neuropeptides, oxytocin (OXT) and arginine vasopressin (AVP), in mammalian social behaviours. Recent molecular genetic studies of the human arginine vasopressin 1a (AVPR1a) and oxytocin (OXTR) receptors have strengthened the evidence regarding the role of these two neuropeptides in a range of normal and pathological behaviours. Significant association between both AVPR1a repeat regions and OXTR single nucleotide polymorphisms (SNPs) with risk for autism has been provisionally shown which was mediated by socialization skills in our study. AVPR1a has also been linked to eating behaviour in both clinical and non-clinical groups, perhaps reflecting the social and ritualistic side of eating behaviour. Evidence also suggests that repeat variations in AVPR1a are associated with two other social domains in Homo sapiens: music and altruism. AVPR1a was associated with dance and musical cognition which we theorize as reflecting the ancient role of this hormone in social interactions executed by vocalization, ritual movement and dyadic (mother-offspring) and group communication. Finally, we have shown that individual differences in allocation of funds in the dictator game, a laboratory game of pure altruism, is predicted by length of the AVPR1a RS3 promoter-region repeat echoing the mechanism of this hormone's action in the vole model of affiliative behaviours and facilitation of positive group interactions. While still in its infancy, the current outlook for molecular genetic investigations of AVP-OXT continues to be fascinating. Future studies should profitably focus on pharmacogenomic and genomic imaging strategies facilitated by the ease and efficacy of manipulating AVP-OXT neurotransmission by intranasal administration. Importantly, physiological measures, behavioural paradigms and brain activation can be informed by considering between-group and also within-group individual differences defined by common polymorphisms. Ultimately, investigators should strive to develop a cohesive model explaining how genomic variations are translated into individual and group differences in higher-order social behaviours.

"In-group love" and "out-group hate" as motives for individual participation in intergroup conflict: a new game paradigm.

What motivates individual self-sacrificial behavior in intergroup conflicts? Is it the altruistic desire to help the in-group or the aggressive drive to hurt the out-group? This article introduces a new game paradigm, the intergroup prisoner's dilemma-maximizing difference (IPD-MD) game, designed specifically to distinguish between these two motives. The game involves two groups. Each group member is given a monetary endowment and can decide how much of it to contribute. Contribution can be made to either of two pools, one that benefits the in-group at a personal cost and another that, in addition, harms the out-group. An experiment demonstrated that contributions in the IPD-MD game are made almost exclusively to the cooperative, within-group pool. Moreover, preplay intragroup communication increases intragroup cooperation, but not intergroup competition. These results are compared with those observed in the intergroup prisoner's dilemma game, in which group members' contributions are restricted to the competitive, between-group pool.

Perceiving intergroup conflict: from game models to mental templates.

This article puts forward a parsimonious framework for studying subjective perceptions of real-life intergroup conflicts. Four studies were conducted to explore how individuals perceive the strategic properties of the Israeli-Palestinian conflict. Studies 1 and 2 found theory-driven associations between people's subjective perception of the conflict's structure as a Chicken, Assurance, or Prisoner's Dilemma game and their ingroup/outgroup perceptions, national identification, religiosity, political partisanship, voting behavior, and right-wing authoritarianism. Studies 3 and 4 manipulated the saliency of the needs for cognitive closure and security, respectively, demonstrating that these needs affect people's endorsement of the game models as descriptions of the conflict.

Intergroup conflict: individual, group, and collective interests.

Intergroup conflicts generally involve conflicts of interests within the competing groups as well. This article outlines a taxonomy of games, called team games, which incorporates the intragroup and intergroup levels of conflict. Its aims are to provide a coherent framework for analyzing the prototypical problems of cooperation and competition that arise within and between groups, and to review an extensive research program that has used this framework to study individual and group behavior in the laboratory. Depending on the game's payoff structure, contradictions or conflicts are created among the rational choices at the individual, group, and collective levels-a generalization of the contradiction between individual and collective rationality occurring in the traditional mixed-motive games. These contradictions are studied so as to identify the theoretical and behavioral conditions that determine which level of rationality prevails.