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Watson R, Morgan TJH, Kendal RL, Van de Vyver J, Kendal J. Investigating the effects of social information on spite in an online game. EVOLUTIONARY HUMAN SCIENCES 2024; 6:e26. [PMID: 38689896 PMCID: PMC11058593 DOI: 10.1017/ehs.2024.18] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2023] [Revised: 12/15/2023] [Accepted: 03/27/2024] [Indexed: 05/02/2024] Open
Abstract
While humans are highly cooperative, they can also behave spitefully. Yet spite remains understudied. Spite can be normatively driven and while previous experiments have found some evidence that cooperation and punishment may spread via social learning, no experiments have considered the social transmission of spiteful behaviour. Here we present an online experiment where, following an opportunity to earn wealth, we asked participants to choose an action towards an anonymous partner across a full spectrum of social behaviour, from spite to altruism. In accordance with cultural evolutionary theory, participants were presented with social information that varied in source and content. Across six conditions, we informed participants that either the majority or the highest earner had chosen to behave spitefully, neutrally or altruistically. We found an overall tendency towards altruism, but at lower levels among those exposed to spite compared with altruism. We found no difference between social information that came from the majority or the highest earner. Exploratory analysis revealed that participants' earnings negatively correlated with altruistic behaviour. Our results contrast with previous literature that report high rates of spite in experimental samples and a greater propensity for individuals to copy successful individuals over the majority.
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Affiliation(s)
- Robin Watson
- Durham Cultural Evolution Research Centre, Anthropology Department, Durham DH1 3LE, UK
- Department of Anthropology, Durham University, Dawson Building, South Road, Durham DH1 3LE, UK
| | - Thomas J. H. Morgan
- School of Human Evolution and Social Change, Arizona State University, 900 South Cady Mall, Tempe, AZ 85287, USA
- Institute of Human Origins, Arizona State University, 777 E University Drive, Tempe, AZ 85287, USA
| | - Rachel L. Kendal
- Durham Cultural Evolution Research Centre, Anthropology Department, Durham DH1 3LE, UK
- Department of Anthropology, Durham University, Dawson Building, South Road, Durham DH1 3LE, UK
| | - Julie Van de Vyver
- Psychology Department, Durham University, Upper Mountjoy, South Road, Durham DH1 3LE, UK
| | - Jeremy Kendal
- Durham Cultural Evolution Research Centre, Anthropology Department, Durham DH1 3LE, UK
- Department of Anthropology, Durham University, Dawson Building, South Road, Durham DH1 3LE, UK
- Durham Research Methods Centre, Faculty of Social Sciences & Health Arthur Holmes Building, Durham University, Durham DH1 3LE, UK
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Scott TW, Wild G. How to make an inclusive-fitness model. Proc Biol Sci 2023; 290:20231310. [PMID: 37788701 PMCID: PMC10547548 DOI: 10.1098/rspb.2023.1310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 09/05/2023] [Indexed: 10/05/2023] Open
Abstract
Social behaviours are typically modelled using neighbour-modulated fitness, which focuses on individuals having their fitness altered by neighbours. However, these models are either interpreted using inclusive fitness, which focuses on individuals altering the fitness of neighbours, or not interpreted at all. This disconnect leads to interpretational mistakes and obscures the adaptive significance of behaviour. We bridge this gap by presenting a systematic methodology for constructing inclusive-fitness models. We find a behaviour's 'inclusive-fitness effect' by summing primary and secondary deviations in reproductive value. Primary deviations are the immediate result of a social interaction; for example, the cost and benefit of an altruistic act. Secondary deviations are compensatory effects that arise because the total reproductive value of the population is fixed; for example, the increased competition that follows an altruistic act. Compared to neighbour-modulated fitness methodologies, our approach is often simpler and reveals the model's inclusive-fitness narrative clearly. We implement our methodology first in a homogeneous population, with supplementary examples of help under synergy, help in a viscous population and Creel's paradox. We then implement our methodology in a class-structured population, where the advantages of our approach are most evident, with supplementary examples of altruism between age classes, and sex-ratio evolution.
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Affiliation(s)
- Thomas W. Scott
- Department of Biology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Geoff Wild
- Department of Mathematics, Western University, 1151 Richmond Street, London, Ontario, Canada N6A 5B7
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A meiotic driver alters sperm form and function in house mice: a possible example of spite. Chromosome Res 2022; 30:151-164. [PMID: 35648282 PMCID: PMC9508062 DOI: 10.1007/s10577-022-09695-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 03/30/2022] [Accepted: 04/19/2022] [Indexed: 11/03/2022]
Abstract
The ability to subvert independent assortment of chromosomes is found in many meiotic drivers, such as the t haplotype in house mice Mus musculus, in which the t-bearing chromosomal homolog is preferentially transmitted to offspring. This is explained by a poison-antidote system, in which developing + and t sperm in testes of + /t males are exposed to 'poison' coded by t loci, from which t sperm are protected, allowing t sperm an overwhelming fertilisation advantage in monogamous matings. This system is thought to result in poorly and normally motile sperm subpopulations within + /t sperm, leaving t sperm unharmed. Conversely, we found that the fastest quartile of sperm from + /t males swam more slowly, both forwards and along their travel path, and had reduced straightness and linearity, compared to the fastest quartile of + / + sperm. Moreover, sperm from + /t males had shorter tails and narrower heads than + / + sperm, and these morphological differences covaried with motility differences. Finally, + /t traits did not show evidence of bimodal distributions. We conclude that the t haplotype drive results in lasting damage to the motility of both + and t developing sperm, although previous studies indicate that + must be more harmed than t sperm. This damage to all sperm may explain the low success of + /t males in sperm competition with + / + males, seen in earlier studies. We propose that the harm the t causes to itself could be termed 'spiteful', which may also be common to other gamete-harming meiotic drive systems.
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Bruner JP, Smead R. Tag-based Spite with Correlated Interactions. J Theor Biol 2022; 540:111052. [PMID: 35247376 DOI: 10.1016/j.jtbi.2022.111052] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 01/16/2022] [Accepted: 02/02/2022] [Indexed: 11/27/2022]
Abstract
We use evolutionary game theory to study the evolution of harming behavior (spite) in settings involving both tags and (anti-)correlated interaction. Our results show an interesting interaction between these mechanisms. The presence of tags shows that pure spite is less likely to evolve when theoretically expected, but that conditional spite is more likely than expected. Moreover, we identify a novel tag-based equilibrium where spite occurs within but not between groups. We discuss implications for the evolution of spite, punishment, and the methodological approach of using exogenous parameters to represent (anti-)correlated interactions.
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Affiliation(s)
- Justin P Bruner
- Department of Political Economy and Moral Science, University of Arizona.
| | - Rory Smead
- Department of Philosophy and Religion, Northeastern University.
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Krupp DB, Maciejewski W. The evolution of extraordinary self-sacrifice. Sci Rep 2022; 12:90. [PMID: 34997081 PMCID: PMC8741978 DOI: 10.1038/s41598-021-04192-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2021] [Accepted: 12/10/2021] [Indexed: 11/30/2022] Open
Abstract
From a theoretical perspective, individuals are expected to sacrifice their welfare only when the benefits outweigh the costs. In nature, however, the costs of altruism and spite can be extreme, as in cases of irreversible sterility and self-destructive weaponry. Here we show that “extraordinary” self-sacrifice—in which actors pay costs that exceed the benefits they give or the costs they impose on recipients—can evolve in structured populations, where social actions bring secondary benefits to neighboring kin. When given information about dispersal, sedentary actors evolve extraordinary altruism towards dispersing kin. Likewise, when given information about dispersal and kinship, sedentary actors evolve extraordinary spite towards sedentary nonkin. Our results can thus be summed up by a simple rule: extraordinary self-sacrifice evolves when the actor’s neighbors are close kin and the recipient’s neighbors are not.
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Affiliation(s)
- D B Krupp
- Department of Interdisciplinary Studies, Lakehead University, Orillia, ON, Canada.
| | - Wes Maciejewski
- Department of Mathematics, San José State University, San José, CA, USA
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