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Massaro AP, Gilby IC, Desai N, Weiss A, Feldblum JT, Pusey AE, Wilson ML. Correlates of individual participation in boundary patrols by male chimpanzees. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210151. [PMID: 35369753 DOI: 10.1098/rstb.2021.0151] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Group territory defence poses a collective action problem: individuals can free-ride, benefiting without paying the costs. Individual heterogeneity has been proposed to solve such problems, as individuals high in reproductive success, rank, fighting ability or motivation may benefit from defending territories even if others free-ride. To test this hypothesis, we analysed 30 years of data from chimpanzees (Pan troglodytes) in the Kasekela community, Gombe National Park, Tanzania (1978-2007). We examined the extent to which individual participation in patrols varied according to correlates of reproductive success (mating rate, rank, age), fighting ability (hunting), motivation (scores from personality ratings), costs of defecting (the number of adult males in the community) and gregariousness (sighting frequency). By contrast to expectations from collective action theory, males participated in patrols at consistently high rates (mean ± s.d. = 74.5 ± 11.1% of patrols, n = 23 males). The best predictors of patrol participation were sighting frequency, age and hunting participation. Current and former alpha males did not participate at a higher rate than males that never achieved alpha status. These findings suggest that the temptation to free-ride is low, and that a mutualistic mechanism such as group augmentation may better explain individual participation in group territorial behaviour. This article is part of the theme issue 'Intergroup conflict across taxa'.
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Affiliation(s)
- Anthony P Massaro
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55414, USA
| | - Ian C Gilby
- School of Human Evolution and Social Change, Arizona State University, Tempe, AZ 85281, USA.,Institute of Human Origins, Arizona State University, Tempe, AZ 85281, USA
| | - Nisarg Desai
- Department of Anthropology, University of Minnesota, Minneapolis, MN 55414, USA
| | - Alexander Weiss
- National Evolutionary Synthesis Center, Durham, NC 27705, USA.,Department of Psychology, School of Philosophy, Psychology and Language Sciences, University of Edinburgh, 7 George Square, Edinburgh EH8 9JZ, UK
| | - Joseph T Feldblum
- Department of Anthropology, University of Michigan, Ann Arbor, MI 48109, USA.,Society of Fellows, University of Michigan, Ann Arbor, MI 48109, USA
| | - Anne E Pusey
- Department of Evolutionary Anthropology, Duke University, Durham, NC 27708, USA
| | - Michael L Wilson
- Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, MN 55414, USA.,Department of Anthropology, University of Minnesota, Minneapolis, MN 55414, USA.,Institute on the Environment, University of Minnesota, St. Paul, MN 55414, USA
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Triki Z, Daughters K, De Dreu CKW. Oxytocin has 'tend-and-defend' functionality in group conflict across social vertebrates. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210137. [PMID: 35369742 PMCID: PMC8977669 DOI: 10.1098/rstb.2021.0137] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Across vertebrate species, intergroup conflict confronts individuals with a tension between group interests best served by participation in conflict and personal interest best served by not participating. Here, we identify the neurohormone oxytocin as pivotal to the neurobiological regulation of this tension in distinctly different group-living vertebrates, including fishes, birds, rodents, non-human primates and humans. In the context of intergroup conflict, a review of emerging work on pro-sociality suggests that oxytocin and its fish and birds homologues, isotocin and mesotocin, respectively, can elicit participation in group conflict and aggression. This is because it amplifies (i) concern for the interests of genetically related or culturally similar ‘in-group’ others and (ii) willingness to defend against outside intruders and enemy conspecifics. Across a range of social vertebrates, oxytocin can induce aggressive behaviour to ‘tend-and-defend’ the in-group during intergroup contests. This article is part of the theme issue ‘Intergroup conflict across taxa’.
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Affiliation(s)
- Zegni Triki
- Department of Zoology, Stockholm University, Stockholm, Sweden
| | | | - Carsten K W De Dreu
- Institute of Psychology, Leiden University, Leiden, The Netherlands.,Center for Research in Experimental Economics and Political Decision Making, University of Amsterdam, Amsterdam, The Netherlands
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De Dreu CKW, Triki Z. Intergroup conflict: origins, dynamics and consequences across taxa. Philos Trans R Soc Lond B Biol Sci 2022; 377:20210134. [PMID: 35369751 PMCID: PMC8977662 DOI: 10.1098/rstb.2021.0134] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Although uniquely destructive and wasteful, intergroup conflict and warfare are not confined to humans. They are seen across a range of group-living species, from social insects, fishes and birds to mammals, including nonhuman primates. With its unique collection of theory, research and review contributions from biology, anthropology and economics, this theme issue provides novel insights into intergroup conflict across taxa. Here, we introduce and organize this theme issue on the origins and consequences of intergroup conflict. We provide a coherent framework by modelling intergroup conflicts as multi-level games of strategy in which individuals within groups cooperate to compete with (individuals in) other groups for scarce resources, such as territory, food, mating opportunities, power and influence. Within this framework, we identify cross-species mechanisms and consequences of (participating in) intergroup conflict. We conclude by highlighting crosscutting innovations in the study of intergroup conflict set forth by individual contributions. These include, among others, insights on how within-group heterogeneities and leadership relate to group conflict, how intergroup conflict shapes social organization and how climate change and environmental degradation transition intergroup relations from peaceful coexistence to violent conflict. This article is part of the theme issue ‘Intergroup conflict across taxa’.
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Affiliation(s)
- Carsten K W De Dreu
- Institute of Psychology, Leiden University, Leiden, The Netherlands.,Center for Research in Experimental Economics and Political Decision Making, University of Amsterdam, Amsterdam, The Netherlands
| | - Zegni Triki
- Department of Zoology, Stockholm University, Stockholm, Sweden
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