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Evolution of indirect reciprocity by image scoring


Darwinian evolution has to provide an explanation for cooperative behaviour. Theories of cooperation are based on kin selection (dependent on genetic relatedness)1,2, group selection3,4,5 and reciprocal altruism6,7,8. The idea of reciprocal altruism usually involves direct reciprocity: repeated encounters between the same individuals allow for the return of an altruistic act by the recipient10,11,12,13,14,15,16. Here we present a new theoretical framework, which is based on indirect reciprocity17 and does not require the same two individuals ever to meet again. Individual selection can nevertheless favour cooperative strategies directed towards recipients that have helped others in the past. Cooperation pays because it confers the image of a valuable community member to the cooperating individual. We present computer simulations and analytic models that specify the conditions required for evolutionary stability18 of indirect reciprocity. We show that the probability of knowing the ‘image’ of the recipient must exceed the cost-to-benefit ratio of the altruistic act. We propose that the emergence of indirect reciprocity was a decisive step for the evolution of human societies.

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Figure 1: Cooperation wins in a computer simulation of indirect reciprocity.
Figure 2: Long-term evolution of indirect reciprocity under mutation and selection.
Figure 3: Indirect reciprocity with incomplete information about the image score of other players.
Figure 4: A further dimension is added to the game if donors base their decision to cooperate not only on the image score of the recipient but also on their own score.

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  1. Hamilton, W. D. The evolution of altruistic behaviour. Am. Nat. 97, 354–356 (1963).

    Article  Google Scholar 

  2. Hamilton, W. D. The genetical evolution of social behaviour. J. Theor. Biol. 7, 1–16 (1964).

    Article  CAS  Google Scholar 

  3. Williams, G. C. Group Selection (Aldine–Atherton, Chicago, (1971).

    Google Scholar 

  4. Eshel, I. On the neighbourhood effect and evolution of altruistic traits. Theor. Popul. Biol. 3, 258–277 (1972).

    Article  MathSciNet  CAS  Google Scholar 

  5. Wilson, D. S. & Sober, E. Reintroducing group selection to the human behavioural sciences. Behav. Brain Sci. 17, 585–654 (1994).

    Article  Google Scholar 

  6. Trivers, R. The evolution of reciprocal altruism. Q. Rev. Biol. 46, 35–57 (1971).

    Article  Google Scholar 

  7. Axelrod, R. & Hamilton, W. D. The evolution of cooperation. Science 211, 1390 (1981).

    Article  ADS  MathSciNet  CAS  Google Scholar 

  8. Axelrod, R. The Evolution of Cooperation (Basic Books, New York, (1984).

    MATH  Google Scholar 

  9. Nowak, M. A. & May, R. M. Evolutionary games and spatial chaos. Nature 359, 826–829 (1992).

    Article  ADS  Google Scholar 

  10. Michod, R. E. & Sanderson, M. J. in Evolution: Essays in Honor of John Maynard Smith (eds Greenwood, P. J., Harvey, P. & Slatkin, M.) 95–106 (Cambridge Univ. Press, Cambridge, (1985).

    Google Scholar 

  11. Peck, J. & Feldman, M. The evolution of helping in large, randomly mixed populations. Am. Nat. 127, 209–221 (1985).

    Article  Google Scholar 

  12. Milinski, M. Tit for tat in sticklebacks and the evolution of cooperation. Nature 325, 433–435 (1987).

    Article  ADS  CAS  Google Scholar 

  13. May, R. M. More evolution of cooperation. Nature 327, 15–17 (1987).

    Article  ADS  Google Scholar 

  14. Dugatkin, L. A. Mesterton-Gibbons, M. & Houston, A. I. Beyond the prisoner's dilemma: towards models to discriminate among mechanism of cooperation in nature. Trends Ecol. Evol. 7, 202–205 (1992).

    Article  CAS  Google Scholar 

  15. Nowak, M. A. & Sigmund, K. Tit for tat in heterogeneous populations. Nature 355, 250–253 (1992).

    Article  ADS  Google Scholar 

  16. Nowak, M. A. & Sigmund, K. Win–stay, lose–shift outperforms tit for tat. Nature 364, 56–58 (1993).

    Article  ADS  CAS  Google Scholar 

  17. Alexander, R. D. The Biology of Moral Systems (Aldine de Gruyter, New York, (1987).

    Google Scholar 

  18. Maynard Smith, J. Evolution and the Theory of Games (Cambridge Univ. Press, Cambridge, (1982).

    Book  Google Scholar 

  19. Wilson, E. O. Sociobiology (Harvard Univ. Press, Cambridge, MA, (1975).

    Google Scholar 

  20. Krebs, J. R. & Davies, N. B. An Introduction to Behavioural Ecology (Blackwell, Oxford, (1987).

    Google Scholar 

  21. Buss, L. The Evolution of Individuality (Princeton Univ. Press, NJ, (1987).

    Google Scholar 

  22. Frank, S. A. The origin of synergistic symbiosis. J. Theor. Biol. 176, 403–410 (1995).

    Article  CAS  Google Scholar 

  23. Binmore, K. G. Fun and Games: a Text on Game Theory (Heath, Lexington, MA, (1992).

    MATH  Google Scholar 

  24. Marler, P. & Evans, C. Bird calls: just emotional displays or something more? Ibis 138, 26–33 (1996).

    Article  Google Scholar 

  25. Zahavi, A. & Zahavi, A. The Handicap Principle: A Missing Piece of Darwin's Puzzle (Oxford Univ. Press, Oxford, (1997).

    MATH  Google Scholar 

  26. Boyd, R. & Richerson, P. J. The evolution of indirect reciprocity. Social Networks 11, 213–236 (1989).

    Article  MathSciNet  Google Scholar 

  27. Sudgen, R. The Economics of Rights, Cooperation and Welfare (Blackwell, Oxford, (1986).

    Google Scholar 

  28. Nowak, M. A. & Sigmund, K. The dynamics of indirect reciprocity. J. Theor. Biol.(submitted).

  29. Pollock, G. B. & Dugatkin, L. A. Reciprocity and the evolution of reputation. J. Theor. Biol. 159, 25–37 (1992).

    Article  Google Scholar 

  30. Hofbauer, J. & Sigmund, K. Evolutionary Games and Population Dynamics (Cambridge Univ. Press, Cambridge, (1998).

    Book  Google Scholar 

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We thank M. Dawkins, A. Kacelnik, J. Krebs and R. May for discussion. Support from the Wellcome Trust is gratefully acknowledged. Part of this work was done at IIASA (Laxenburg).

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Correspondence to Martin A. Nowak.

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Nowak, M., Sigmund, K. Evolution of indirect reciprocity by image scoring. Nature 393, 573–577 (1998).

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