Egas M, Riedl A.

   Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, 1090 GB Amsterdam, The Netherlands. egas@science.uva.nl

   Explaining the evolution and maintenance of cooperation among unrelated individuals is one of the fundamental problems in biology and the social sciences. Recent findings suggest that altruistic punishment is an important mechanism maintaining cooperation among humans. We experimentally explore the boundaries of altruistic punishment to maintain cooperation by varying both the cost and the impact of punishment, using an exceptionally extensive subject pool. Our results show that cooperation is only maintained if conditions for altruistic punishment are relatively favourable: low cost for the punisher and high impact on the punished. Our results indicate that punishment is strongly governed by its cost-to-impact ratio and that its effect on cooperation can be pinned down to one single variable: the threshold level of free-riding that goes unpunished. Additionally, actual pay-offs are the lowest when altruistic punishment maintains cooperation, because the pay-off destroyed through punishment exceeds the gains from increased cooperation. Our results are consistent with the interpretation that punishment decisions come from an amalgam of emotional response and cognitive cost-impact analysis and suggest that altruistic punishment alone can hardly maintain cooperation under multi-level natural selection. Uncovering the workings of altruistic punishment as has been done here is important because it helps predicting under which conditions altruistic punishment is expected to maintain cooperation.

   PMID: 18198144 [PubMed - in process]

2: J Theor Biol. 2007 Nov 21;249(2):198-205. Epub 2007 Aug 8.
Related Articles, Links
    Click here to read
    Selfish punishment: altruism can be maintained by competition among cheaters.

   Eldakar OT, Farrell DL, Wilson DS.

   Department of Biological Sciences, Binghamton University, Binghamton, NY 13902-6000, USA. oeldakar@gmail.com

   Altruistic punishment refers to a class of behaviors that deters cheating at a cost to the punisher, making it a form of second-order altruism. Usually, it is assumed that the punishers are themselves "solid citizens" who refrain from cheating. We show in a simulation model that altruism and punishment paradoxically become negatively correlated, leading to a form of selfish punishment. Examples of selfish punishment can be found in organisms as diverse as wasps, birds, and humans.

   PMID: 17854839 [PubMed - in process]

3: Am Nat. 2007 Jul;170(1):21-36. Epub 2007 May 11.
Related Articles, Links
    Click here to read
    Erratum in:

       * Am Nat. 2007 Oct;170(4):661.

   Strong reciprocity or strong ferocity? A population genetic view of the evolution of altruistic punishment.

   Lehmann L, Rousset F, Roze D, Keller L.

   Morrison Institute for Population and Resource Studies, Stanford University, Stanford, California 94305, USA. lehmann@stanford.edu

   Strong reciprocity, defined as a predisposition to help others and to punish those that are not helping, has been proposed as a potent force leading to the evolution of cooperation and altruism. However, the conditions under which strong reciprocity might be favored are not clear. Here we investigate the selective pressure on strong reciprocity by letting both limited dispersal (i.e., spatial structure) and recombination between helping and punishment jointly determine the evolutionary dynamics of strong reciprocity. Our analytical model suggests that when helping and punishment are perfectly linked traits (no recombination occurring between them), strong reciprocity can spread even when the initial frequency of strong reciprocators is close to 0 in the population (i.e., a rare mutant can invade). By contrast, our results indicate that when recombination can occur between helping and punishment (i.e., both traits coevolve) and is stronger than selection, punishment is likely to invade a population of defectors only when it gives a direct fitness benefit to the actor. Overall, our results delineate the conditions under which strong reciprocity is selected for in a spatially structured population and highlight that the forces behind its evolution involves kinship (be it genetic or cultural).

   Publication Types:

       * Research Support, Non-U.S. Gov't

   PMID: 17853989 [PubMed - indexed for MEDLINE]

4: J Evol Biol. 2007 Mar;20(2):415-32.
Related Articles, Links
    Click here to read
    Comment in:

       * J Evol Biol. 2008 Jan;21(1):368-73.

   Social semantics: altruism, cooperation, mutualism, strong reciprocity and group selection.

   West SA, Griffin AS, Gardner A.

   Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, King's Buildings, Edinburgh, UK. stu.west@ed.ac.uk

   From an evolutionary perspective, social behaviours are those which have fitness consequences for both the individual that performs the behaviour, and another individual. Over the last 43 years, a huge theoretical and empirical literature has developed on this topic. However, progress is often hindered by poor communication between scientists, with different people using the same term to mean different things, or different terms to mean the same thing. This can obscure what is biologically important, and what is not. The potential for such semantic confusion is greatest with interdisciplinary research. Our aim here is to address issues of semantic confusion that have arisen with research on the problem of cooperation. In particular, we: (i) discuss confusion over the terms kin selection, mutualism, mutual benefit, cooperation, altruism, reciprocal altruism, weak altruism, altruistic punishment, strong reciprocity, group selection and direct fitness; (ii) emphasize the need to distinguish between proximate (mechanism) and ultimate (survival value) explanations of behaviours. We draw examples from all areas, but especially recent work on humans and microbes.

   Publication Types:

       * Research Support, Non-U.S. Gov't
        * Review

   PMID: 17305808 [PubMed - indexed for MEDLINE]

5: Science. 2006 Apr 7;312(5770):108-11.
Related Articles, Links
    Click here to read
    Comment in:

       * Science. 2006 Apr 7;312(5770):60-1.

   The competitive advantage of sanctioning institutions.

   Gürerk O, Irlenbusch B, Rockenbach B.

   University of Erfurt, Nordhäuser Strasse 63, 99089 Erfurt, Germany.

   Understanding the fundamental patterns and determinants of human cooperation and the maintenance of social order in human societies is a challenge across disciplines. The existing empirical evidence for the higher levels of cooperation when altruistic punishment is present versus when it is absent systematically ignores the institutional competition inherent in human societies. Whether punishment would be deliberately adopted and would similarly enhance cooperation when directly competing with nonpunishment institutions is highly controversial in light of recent findings on the detrimental effects of punishment. We show experimentally that a sanctioning institution is the undisputed winner in a competition with a sanction-free institution. Despite initial aversion, the entire population migrates successively to the sanctioning institution and strongly cooperates, whereas the sanction-free society becomes fully depopulated. The findings demonstrate the competitive advantage of sanctioning institutions and exemplify the emergence and manifestation of social order driven by institutional selection.

   PMID: 16601192 [PubMed - indexed for MEDLINE]

6: Nature. 2006 Jan 26;439(7075):466-9. Epub 2006 Jan 18.
Related Articles, Links
    Click here to read
    Empathic neural responses are modulated by the perceived fairness of others.

   Singer T, Seymour B, O'Doherty JP, Stephan KE, Dolan RJ, Frith CD.

   Wellcome Department of Imaging Neuroscience, University College of London, London WC1N 3AR, UK. t.singer@fil.ion.ucl.ac.uk

   The neural processes underlying empathy are a subject of intense interest within the social neurosciences. However, very little is known about how brain empathic responses are modulated by the affective link between individuals. We show here that empathic responses are modulated by learned preferences, a result consistent with economic models of social preferences. We engaged male and female volunteers in an economic game, in which two confederates played fairly or unfairly, and then measured brain activity with functional magnetic resonance imaging while these same volunteers observed the confederates receiving pain. Both sexes exhibited empathy-related activation in pain-related brain areas (fronto-insular and anterior cingulate cortices) towards fair players. However, these empathy-related responses were significantly reduced in males when observing an unfair person receiving pain. This effect was accompanied by increased activation in reward-related areas, correlated with an expressed desire for revenge. We conclude that in men (at least) empathic responses are shaped by valuation of other people's social behaviour, such that they empathize with fair opponents while favouring the physical punishment of unfair opponents, a finding that echoes recent evidence for altruistic punishment.

   Publication Types:

       * Research Support, Non-U.S. Gov't

   PMID: 16421576 [PubMed - indexed for MEDLINE]

7: Proc Natl Acad Sci U S A. 2006 Jan 10;103(2):495-7. Epub 2005 Dec 30.
Related Articles, Links
    Click here to read
    Punishing and abstaining for public goods.

   Brandt H, Hauert C, Sigmund K.

   Vienna University of Economics and Business Administration, A-1090 Vienna, Austria.

   The evolution of cooperation within sizable groups of nonrelated humans offers many challenges for our understanding. Current research has highlighted two factors boosting cooperation in public goods interactions, namely, costly punishment of defectors and the option to abstain from the joint enterprise. A recent modeling approach has suggested that the autarkic option acts as a catalyzer for the ultimate fixation of altruistic punishment. We present an alternative, more microeconomically based model that yields a bistable outcome instead. Evolutionary dynamics can lead either to a Nash equilibrium of punishing and nonpunishing cooperators or to an oscillating state without punishers.

   PMID: 16387857 [PubMed - indexed for MEDLINE]

8: Proc Natl Acad Sci U S A. 2005 May 10;102(19):7047-9. Epub 2005 Apr 27.
Related Articles, Links
    Click here to read Click here to read
    Altruistic punishment and the origin of cooperation.

   Fowler JH.

   Department of Political Science, University of California, 1 Shields Avenue, Davis, CA 95616, USA. jhfowler@ucdavis.edu

   How did human cooperation evolve? Recent evidence shows that many people are willing to engage in altruistic punishment, voluntarily paying a cost to punish noncooperators. Although this behavior helps to explain how cooperation can persist, it creates an important puzzle. If altruistic punishment provides benefits to nonpunishers and is costly to punishers, then how could it evolve? Drawing on recent insights from voluntary public goods games, I present a simple evolutionary model in which altruistic punishers can enter and will always come to dominate a population of contributors, defectors, and nonparticipants. The model suggests that the cycle of strategies in voluntary public goods games does not persist in the presence of punishment strategies. It also suggests that punishment can only enforce payoff-improving strategies, contrary to a widely cited "folk theorem" result that suggests that punishment can allow the evolution of any strategy.

   PMID: 15857950 [PubMed - indexed for MEDLINE]

   PMCID: PMC1100778

9: Nature. 2005 Jan 6;433(7021):1 p following 32; discussion following 32.
Related Articles, Links
    Click here to read
    Comment on:

       * Nature. 2002 Jan 10;415(6868):137-40.

   Human behaviour: Egalitarian motive and altruistic punishment.

   Fowler JH, Johnson T, Smirnov O.

   Department of Political Science, University of California, Davis, One Shields Avenue, Davis, California 95616, USA. jhfowler@ucdavis.edu

   Altruistic punishment is a behaviour in which individuals punish others at a cost to themselves in order to provide a public good. Fehr and Gächter present experimental evidence in humans indicating that negative emotions towards non-cooperators motivate punishment, which, in turn, provokes a high degree of cooperation. Using Fehr and Gächter's original data, we provide an alternative analysis of their experiment that suggests that egalitarian motives are more important than motives for punishing non-cooperative behaviour. This finding is consistent with evidence that humans may have an evolutionary incentive to punish the highest earners in order to promote equality, rather than cooperation.

   Publication Types:

       * Comment

   PMID: 15637787 [PubMed - indexed for MEDLINE]

10: Curr Opin Neurobiol. 2004 Dec;14(6):784-90.
Related Articles, Links
    Click here to read
    Human altruism: economic, neural, and evolutionary perspectives.

   Fehr E, Rockenbach B.

   Institute for Empirical Research in Economics, University of Zurich, Bluemlisalpstrasse 10, 8006 Zuerich, Switzerland. efehr@iew.unizh.ch

   Human cooperation represents a spectacular outlier in the animal world. Unlike other creatures, humans frequently cooperate with genetically unrelated strangers, often in large groups, with people they will never meet again, and when reputation gains are small or absent. Experimental evidence and evolutionary models suggest that strong reciprocity, the behavioral propensity for altruistic punishment and altruistic rewarding, is of key importance for human cooperation. Here, we review both evidence documenting altruistic punishment and altruistic cooperation and recent brain imaging studies that combine the powerful tools of behavioral game theory with neuroimaging techniques. These studies show that mutual cooperation and the punishment of defectors activate reward related neural circuits, suggesting that evolution has endowed humans with proximate mechanisms that render altruistic behavior psychologically rewarding.

   Publication Types:

       * Review

   PMID: 15582384 [PubMed - indexed for MEDLINE]

11: Acta Biotheor. 2004;52(3):155-72.
Related Articles, Links
    Click here to read
    Altruism, altruistic punishment and social investment.

   Jaffe K.

   Universidad Simón Bolívar, Caracas, Venezuela. kjaffe@usb.ve

   The concept of altruism is used in very different forms by computer scientists,economists, philosophers, social scientists, psychologists and biologists. Yet, in order to be useful in social simulations, the concept "altruism" requires a more precise meaning. A quantitative formulation is proposed here, based on the cost/benefit analysis of the altruist and of society at large. This formulation is applied in the analysis of the social dynamic working of behaviors that have been called "altruistic punishments", using the agent based computer model Sociodynamica. The simulations suggest that "altruistic punishment" on its own cannot maintain altruistic behaviors. "Altruistic behavior" is sustainable in the long term only if these behaviors trigger synergetic forces in society that eventually make them produce benefits to most individuals. The simulations suggest however that "altruistic punishment" may work as a "social investment", and is thus better called "decentralized social punishment". This behavior is very efficient in enforcing social norms. The efficiency of decentralized social punishment in enforcing norms was dependent on the type of labor structured of the virtual society. I conclude that what is called "altruistic punishment" emerges as a type of social investment that can evolve either through individual and/or group selection, as a successful device for changing or enforcing norms in a society. Social simulations will help us in better understanding the underlying dynamic working of such devices.

   PMID: 15456982 [PubMed - indexed for MEDLINE]

12: Science. 2004 Aug 27;305(5688):1254-8.
Related Articles, Links
    Click here to read
    Comment in:

       * Science. 2004 Aug 27;305(5688):1246-7.

   The neural basis of altruistic punishment.

   de Quervain DJ, Fischbacher U, Treyer V, Schellhammer M, Schnyder U, Buck A, Fehr E.

   Division of Psychiatry Research, University of Zurich, Lenggstrasse 31, 8029 Zurich, Switzerland. quervain@bli.unizh.ch

   Many people voluntarily incur costs to punish violations of social norms. Evolutionary models and empirical evidence indicate that such altruistic punishment has been a decisive force in the evolution of human cooperation. We used H2 15O positron emission tomography to examine the neural basis for altruistic punishment of defectors in an economic exchange. Subjects could punish defection either symbolically or effectively. Symbolic punishment did not reduce the defector's economic payoff, whereas effective punishment did reduce the payoff. We scanned the subjects' brains while they learned about the defector's abuse of trust and determined the punishment. Effective punishment, as compared with symbolic punishment, activated the dorsal striatum, which has been implicated in the processing of rewards that accrue as a result of goal-directed actions. Moreover, subjects with stronger activations in the dorsal striatum were willing to incur greater costs in order to punish. Our findings support the hypothesis that people derive satisfaction from punishing norm violations and that the activation in the dorsal striatum reflects the anticipated satisfaction from punishing defectors.

   Publication Types:

       * Research Support, Non-U.S. Gov't

   PMID: 15333831 [PubMed - indexed for MEDLINE]

13: Theor Popul Biol. 2004 Feb;65(1):17-28.
Related Articles, Links
    Click here to read
    The evolution of strong reciprocity: cooperation in heterogeneous populations.

   Bowles S, Gintis H.

   Santa Fe Institute, 1399 Hyde Park Road, Santa Fe, NM 87501, USA. bowles@santafe.edu

   How do human groups maintain a high level of cooperation despite a low level of genetic relatedness among group members? We suggest that many humans have a predisposition to punish those who violate group-beneficial norms, even when this imposes a fitness cost on the punisher. Such altruistic punishment is widely observed to sustain high levels of cooperation in behavioral experiments and in natural settings.We offer a model of cooperation and punishment that we call STRONG RECIPROCITY: where members of a group benefit from mutual adherence to a social norm, strong reciprocators obey the norm and punish its violators, even though as a result they receive lower payoffs than other group members, such as selfish agents who violate the norm and do not punish, and pure cooperators who adhere to the norm but free-ride by never punishing. Our agent-based simulations show that, under assumptions approximating likely human environments over the 100000 years prior to the domestication of animals and plants, the proliferation of strong reciprocators when initially rare is highly likely, and that substantial frequencies of all three behavioral types can be sustained in a population. As a result, high levels of cooperation are sustained. Our results do not require that group members be related or that group extinctions occur.

   Publication Types:

       * Research Support, Non-U.S. Gov't

   PMID: 14642341 [PubMed - indexed for MEDLINE]

14: Proc Natl Acad Sci U S A. 2003 Mar 18;100(6):3531-5. Epub 2003 Mar 11.
Related Articles, Links
    Click here to read Click here to read

   The evolution of altruistic punishment.

   Boyd R, Gintis H, Bowles S, Richerson PJ.

   Department of Anthropology, University of California, Los Angeles, CA 90095, USA. boyd@anthro.sscnet.ucla.edu

   Both laboratory and field data suggest that people punish noncooperators even in one-shot interactions. Although such "altruistic punishment" may explain the high levels of cooperation in human societies, it creates an evolutionary puzzle: existing models suggest that altruistic cooperation among nonrelatives is evolutionarily stable only in small groups. Thus, applying such models to the evolution of altruistic punishment leads to the prediction that people will not incur costs to punish others to provide benefits to large groups of nonrelatives. However, here we show that an important asymmetry between altruistic cooperation and altruistic punishment allows altruistic punishment to evolve in populations engaged in one-time, anonymous interactions. This process allows both altruistic punishment and altruistic cooperation to be maintained even when groups are large and other parameter values approximate conditions that characterize cultural evolution in the small-scale societies in which humans lived for most of our prehistory.

   PMID: 12631700 [PubMed]

   PMCID: PMC152327

15: Nature. 2002 Jan 10;415(6868):137-40.
Related Articles, Links
    Click here to read
    Comment in:

       * Nature. 2002 Jan 10;415(6868):125-8.
        * Nature. 2003 Feb 27;421(6926):911-2; discussion 912.
        * Nature. 2005 Jan 6;433(7021):1 p following 32; discussion following 32.

   Altruistic punishment in humans.

   Fehr E, Gächter S.

   University of Zürich, Institute for Empirical Research in Economics, Blümlisalpstrasse 10, CH-8006 Zürich, Switzerland. efehr@iew.unizh.ch

   Human cooperation is an evolutionary puzzle. Unlike other creatures, people frequently cooperate with genetically unrelated strangers, often in large groups, with people they will never meet again, and when reputation gains are small or absent. These patterns of cooperation cannot be explained by the nepotistic motives associated with the evolutionary theory of kin selection and the selfish motives associated with signalling theory or the theory of reciprocal altruism. Here we show experimentally that the altruistic punishment of defectors is a key motive for the explanation of cooperation. Altruistic punishment means that individuals punish, although the punishment is costly for them and yields no material gain. We show that cooperation flourishes if altruistic punishment is possible, and breaks down if it is ruled out. The evidence indicates that negative emotions towards defectors are the proximate mechanism behind altruistic punishment. These results suggest that future study of the evolution of human cooperation should include a strong focus on explaining altruistic punishment.

   Publication Types:

       * Research Support, Non-U.S. Gov't