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Monkeys reject unequal pay

Abstract

During the evolution of cooperation it may have become critical for individuals to compare their own efforts and pay-offs with those of others. Negative reactions may occur when expectations are violated. One theory proposes that aversion to inequity can explain human cooperation within the bounds of the rational choice model1, and may in fact be more inclusive than previous explanations2,3,4,5,6,7,8. Although there exists substantial cultural variation in its particulars, this ‘sense of fairness’ is probably a human universal9,10 that has been shown to prevail in a wide variety of circumstances11,12,13. However, we are not the only cooperative animals14, hence inequity aversion may not be uniquely human. Many highly cooperative nonhuman species seem guided by a set of expectations about the outcome of cooperation and the division of resources15,16. Here we demonstrate that a nonhuman primate, the brown capuchin monkey (Cebus apella), responds negatively to unequal reward distribution in exchanges with a human experimenter. Monkeys refused to participate if they witnessed a conspecific obtain a more attractive reward for equal effort, an effect amplified if the partner received such a reward without any effort at all. These reactions support an early evolutionary origin of inequity aversion.

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Figure 1: Mean percentage ± s.e.m. of failures to exchange for females across the four test types.
Figure 2: Mean percentage ± s.e.m. of failures to exchange in the first 15 trials (black bars) versus the last 10 trials per test (white bars).
Figure 3: A juvenile capuchin monkey shows cheek-to-cheek begging to an eating adult male, cupping his hand next to the adult's food in solicitation.

References

  1. Fehr, E. & Schmidt, K. M. A theory of fairness, competition, and cooperation. Quart. J. Econ. 114, 817–868 (1999)

    Article  Google Scholar 

  2. Andreoni, J. Cooperation in public-goods experiments: kindness or confusion? Am. Econ. Rev. 85, 891–904 (1995)

    Google Scholar 

  3. Fehr, E. & Gachter, S. The puzzle of human cooperation: reply. Nature 421, 912 (2003)

    Article  ADS  CAS  Google Scholar 

  4. Fehr, E. & Gachter, S. Altruistic punishment in humans. Nature 415, 137–140 (2002)

    Article  ADS  CAS  Google Scholar 

  5. Johnson, D. D. P., Stopka, P. & Knights, S. The puzzle of human cooperation. Nature 421, 911–912 (2003)

    Article  ADS  CAS  Google Scholar 

  6. Milinski, M., Semmann, D. & Krambeck, H.-J. Reputation helps solve the ‘tragedy of the commons’. Nature 415, 424–426 (2002)

    Article  ADS  Google Scholar 

  7. Roberts, G. & Sherratt, T. N. Development of cooperative relationships through increasing investment. Nature 394, 175–179 (1998)

    Article  ADS  CAS  Google Scholar 

  8. Wenekind, C. & Milinski, M. Cooperation through image scoring in humans. Science 200, 850–852 (2000)

    Article  ADS  Google Scholar 

  9. Henrich, J. et al. In search of Homo economicus: behavioral experiments in 15 small-scale societies. Am. Econ. Rev. 91, 73–78 (2001)

    Article  Google Scholar 

  10. Henrich, J. Does culture matter in economic behavior? Ultimatum game bargaining among the Machiguenga of the Peruvian Amazon. Am. Econ. Rev. 90, 973–979 (2000)

    Article  Google Scholar 

  11. Fehr, E. & Rockenbach, B. Detrimental effects of sanctions on human altruism. Nature 422, 137–140 (2003)

    Article  ADS  CAS  Google Scholar 

  12. Kahneman, D., Knetsch, J. L. & Thaler, R. Fairness as a constraint on profit seeking: entitlements in the market. Am. Econ. Rev. 76, 728–741 (1986)

    Google Scholar 

  13. Zizzo, D. J. & Oswald, A. Are people willing to pay to reduce other's incomes? Annales d'Econ. Stat. 63–64, 39–62 (2001)

    Google Scholar 

  14. Dugatkin, L. A. Cooperation Among Animals: An Evolutionary Perspective (Oxford Univ. Press, New York, 1997)

    Google Scholar 

  15. de Waal, F. B. M. Good Natured: The Origins of Right and Wrong in Humans and Other Animals (Harvard Univ. Press, Cambridge, Massachusetts, 1996)

    Google Scholar 

  16. de Waal, F. B. M. & Davis, J. M. Capuchin cognitive ecology: cooperation based on projected returns. Neuropsychologia 1492, 1–8 (2002)

    Google Scholar 

  17. di Bitetti, M. S. Evidence for an important social role of allogrooming in a platyrrhine primate. Anim. Behav. 54, 199–211 (1997)

    Article  Google Scholar 

  18. de Waal, F. B. M. Food transfers through mesh in brown capuchins. J. Comp. Psychol. 111, 370–378 (1997)

    Article  CAS  Google Scholar 

  19. Tinklepaugh, O. L. An experimental study of representative factors in monkeys. J. Comp. Psychol. 8, 197–236 (1928)

    Article  Google Scholar 

  20. Andreoni, J., Brown, P. M. & Vesterlund, L. What makes an allocation fair? Some experimental evidence. Games Econ. Behav. 40, 1–24 (2002)

    Article  Google Scholar 

  21. Falk, A., Fehr, E. & Fischbacher, U. On the nature of fair behavior. Econ. Inq. 41, 20–26 (2003)

    Article  Google Scholar 

  22. Frank, R. H. in Evolution and the Capacity for Commitment (ed. Nesse, R. M.) 57–76 (Russell Sage Foundation, New York, 2001)

    Google Scholar 

  23. Sanfey, A. G., Rilling, J. K., Aronson, J. A., Nystrom, L. E. & Cohen, J. D. The neural basis of economic decision-making in the Ultimatum game. Science 300, 1755–1758 (2003)

    Article  ADS  CAS  Google Scholar 

  24. Frank, R. H. Passions Within Reason: The Strategic Role of the Emotions (W. W. Norton, New York, 1988)

    Google Scholar 

  25. Hirschleifer, J. in The Latest on the Best: Essays in Evolution and Optimality (ed. Dupre, J.) 307–326 (MIT Press, Cambridge, Massachusetts, 1987)

    Google Scholar 

  26. Nesse, R. M. in Evolution and the Capacity for Commitment (ed. Nesse, R. M.) 1–44 (Russell Sage Foundation, New York, 2001)

    Google Scholar 

  27. Dugatkin, L. A. in Evolution and the Capacity for Commitment (ed. Nesse, R. M.) 120–137 (Russell Sage Foundation, New York, 2001)

    Google Scholar 

  28. de Waal, F. B. M. & Berger, M. L. Payment for labour in monkeys. Nature 404, 563 (2000)

    Article  ADS  CAS  Google Scholar 

  29. Mendres, K. A. & de Waal, F. B. M. Capuchins do cooperate: the advantage of an intuitive task. Anim. Behav. 60, 523–529 (2000)

    Article  CAS  Google Scholar 

  30. Brosnan, S. F. & de Waal, F. B. M. A proximate perspective on reciprocal altruism. Hum. Nat. 13, 129–152 (2002)

    Article  Google Scholar 

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Acknowledgements

We thank L. Antonucci, K. Bouxsein, J. Davis, C. Freeman and A. Katz for help with data collection and coding, L. Ruttan for comments on the manuscript and R. Earley for statistical advice. Photo by F.d.W.

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Brosnan, S., de Waal, F. Monkeys reject unequal pay. Nature 425, 297–299 (2003). https://doi.org/10.1038/nature01963

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