Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Gains to cooperation drive the evolution of egalitarianism


What conditions favour egalitarianism, that is, muted hierarchies with relatively equal distributions of resources? Here, we combine the hawk–dove and prisoner’s dilemma games to model the effects of economic defensibility, costs of competition and gains from cooperation on egalitarianism, operationalized as the absence of hawks. We show that a ‘leveller’ strategy, which punishes hawkishness in the hawk–dove game with defection in the prisoner’s dilemma, can be evolutionarily stable provided that the gains from cooperation are high relative to the benefits of hawkishness. Under these conditions, rare mutant levellers select for hawks that acquiesce to punishment by playing dove. If these ‘acquiescent hawks’ become common, levellers outperform hawks and establish a new egalitarian equilibrium. An analysis of human foraging groups corroborates these results, as groups with a greater reliance on cooperation are more egalitarian. Cooperation fosters greater equality when individuals can withhold its benefits from would-be dominant individuals.

This is a preview of subscription content, access via your institution

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Fig. 1: What conditions favour the evolution of levelling?.
Fig. 2: Increased gains to cooperation allow the evolution of egalitarianism through levelling.
Fig. 3: Long-run outcomes as a function of gains to cooperation (b) after 100,000 generations.
Fig. 4: Egalitarianism increases with dependence on hunting across 337 foraging societies.
Fig. 5: The effect of the initial frequency of acquiescent hawks (left) and mutation rate m (right) on the evolution of levellers in the simulation.

Similar content being viewed by others

Data availability

The Binford hunter-gatherer data are available at GitHub ( or

Code availability

Code for the simulations and empirical analysis is available at GitHub (


  1. Standen, V. & Foley, R. A. Comparative Socioecology: The Behavioural Ecology of Humans and Other Mammals (Blackwell Scientific Publications, 1989).

  2. Sterck, E. H. M., Watts, D. P. & van Schaik, C. P. The evolution of female social relationships in nonhuman primates. Behav. Ecol. Sociobiol. 41, 291–309 (1997).

    Article  Google Scholar 

  3. Jaeggi, A. V., Boose, K. F., White, F. J. & Gurven, M. Obstacles and catalysts of cooperation in humans, bonobos, and chimpanzees: behavioural reaction norms can help explain variation in sex roles, inequality, war and peace. Behaviour 153, 1015–1051 (2016).

    Article  Google Scholar 

  4. Kelly, R. L. The Lifeways of Hunter-Gatherers: The Foraging Spectrum (Cambridge Univ. Press, 2013).

  5. Kaplan, H. S., Hooper, P. L. & Gurven, M. The evolutionary and ecological roots of human social organization. Philos. Trans. R. Soc. B 364, 3289–3299 (2009).

    Article  Google Scholar 

  6. Wilkinson, R. G. Unhealthy Societies: The Afflictions of Inequality (Routledge, 2002).

  7. Daly, M. & Wilson, M. Homicide (Transaction Publishers, 1988).

  8. Sapolsky, R. M. The influence of social hierarchy on primate health. Science 308, 648–652 (2005).

    Article  CAS  PubMed  Google Scholar 

  9. Brown, J. L. The evolution of diversity in avian territorial systems. Wilson Bull. 76, 160–169 (1964).

    Google Scholar 

  10. Dyson-Hudson, R. & Smith, E. A. Human territoriality: an ecological reassessment. Am. Anthropol. 80, 21–41 (1978).

    Article  Google Scholar 

  11. Packer, C., Pusey, A. E. & Eberly, L. E. Egalitarianism in female African lions. Science 293, 690–693 (2001).

    Article  CAS  PubMed  Google Scholar 

  12. Gintis, H., van Schaik, C. & Boehm, C. Zoon politikon: the evolutionary origins of human socio-political systems. Behav. Processes 161, 17–30 (2019).

    Article  PubMed  Google Scholar 

  13. Okada, D. & Bingham, P. M. Human uniqueness-self-interest and social cooperation. J. Theor. Biol. 253, 261–270 (2008).

    Article  PubMed  Google Scholar 

  14. Pandit, S. A. & van Schaik, C. P. A model for leveling coalitions among primate males: toward a theory of egalitarianism. Behav. Ecol. Sociobiol. 55, 161–168 (2003).

    Article  Google Scholar 

  15. Gavrilets, S., Duenez-Guzman, E. A. & Vose, M. D. Dynamics of alliance formation and the egalitarian revolution. PLoS ONE 3, e3293 (2008).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  16. Gavrilets, S. On the evolutionary origins of the egalitarian syndrome. Proc. Natl Acad. Sci. USA 109, 14069–14074 (2012).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  17. Boehm, C. Hierarchy in the Forest: The Evolution of Egalitarian Behavior (Harvard Univ. Press, 1999).

  18. Majolo, B., de Bortoli Vizioli, A. & Lehmann, J. The effect of intergroup competition on intragroup affiliation in primates. Anim. Behav. 114, 13–19 (2016).

    Article  Google Scholar 

  19. Wiessner, P. Levelling the hunter: constraints on the status quest in foraging societies. in Food and the Status Quest (eds Wiessner, P. & Schiefenhovel, W.) 171–192 (Berghahn Books, 1996).

  20. Maynard Smith, J. The theory of games and the evolution of animal conflicts. J. Theor. Biol. 47, 209–221 (1974).

    Article  Google Scholar 

  21. Axelrod, R. & Hamilton, W. D. The evolution of cooperation. Science 212, 1390–1396 (1981).

    Article  Google Scholar 

  22. Kaplan, H. & Gurven, M. The natural history of human food sharing and cooperation. in Moral Sentiments and Material Interests: The Foundations of Cooperation in Economic Life (eds Gintis, H. et al.) 75–113 (MIT Press, 2005).

  23. Kaplan, H. & Hill, K. Food sharing among Ache foragers: tests of explanatory hypotheses. Curr. Anthropol. 26, 223–246 (1985).

    Article  Google Scholar 

  24. Winterhalder, B. Diet choice, risk, and food sharing in a stochastic environment. J. Anthropol. Archaeol. 392, 369–392 (1986).

    Article  Google Scholar 

  25. Gurven, M. & Hill, K. Why do men hunt? A reevaluation of ‘man the hunter’ and the sexual division of labor. Curr. Anthropol. 50, 51–74 (2009).

    Article  PubMed  Google Scholar 

  26. Hooper, P. L., Demps, K., Gurven, M., Gerkey, D. & Kaplan, H. S. Skills, division of labour and economies of scale among Amazonian hunters and South Indian honey collectors. Philos. Trans. R. Soc. B 370, 20150008 (2015).

    Article  Google Scholar 

  27. Hill, K. Altruistic cooperation during foraging by the Ache, and the evolved human predisposition to cooperate. Hum. Nat. 13, 105–128 (2002).

    Article  PubMed  Google Scholar 

  28. Woodburn, J. Egalitarian societies. Man 17, 431–451 (1982).

    Article  Google Scholar 

  29. Cashdan, E. A. Egalitarianism among hunters and gatherers. Am. Anthropol. 82, 116–120 (1980).

    Article  Google Scholar 

  30. Boehm, C. Egalitarian behavior and reverse dominance hierarchy. Curr. Anthropol. 34, 227–254 (1993).

    Article  Google Scholar 

  31. Marlowe, F. W. et al. The ‘spiteful’ origins of human cooperation. Proc. R. Soc. B 278, 2159–2164 (2010).

    Article  PubMed  PubMed Central  Google Scholar 

  32. Hill, K. R. et al. Co-residence patterns in hunter-gatherer societies show unique human social structure. Science 331, 1286–1289 (2011).

    Article  CAS  PubMed  Google Scholar 

  33. Marlowe, F. W. et al. More ‘altruistic’ punishment in larger societies. Proc. R. Soc. B 275, 587–592 (2008).

    Article  PubMed  Google Scholar 

  34. McElreath, R. & Boyd, R. Mathematical Models of Social Evolution: A Guide for the Perplexed (Univ. Chicago, 2007).

  35. van Damme, E. & Weibull, J. W. Evolution in games with endogenous mistake probabilities. J. Econ. Theory 106, 296–315 (2002).

    Article  Google Scholar 

  36. Naidu, S., Hwang, S. H. & Bowles, S. Evolutionary bargaining with intentional idiosyncratic play. Econ. Lett. 109, 31–33 (2010).

    Article  Google Scholar 

  37. Maynard Smith, J. & Price, G. R. The logic of animal conflict. Nature 246, 15–18 (1973).

    Article  Google Scholar 

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

    Article  CAS  PubMed  Google Scholar 

  39. Hamilton, W. D. The genetical evolution of social behaviour. II. J. Theor. Biol. 7, 17–52 (1964).

  40. Nowak, M. A. Five rules for the evolution of cooperation. Science 314, 1560–1563 (2006).

    Article  CAS  PubMed  PubMed Central  Google Scholar 

  41. Binford, L. F. Constructing Frames of Reference (Univ. California Press, 2001).

  42. Jaeggi, A. V. & Gurven, M. Natural cooperators: food sharing in humans and other primates. Evol. Anthropol. 22, 186–195 (2013).

    Article  PubMed  Google Scholar 

  43. Duffy, K. G., Richard, W. & Silk, J. B. Male chimpanzees exchange political support for mating opportunities. Curr. Biol. 17, R586–R587 (2007).

    Article  CAS  PubMed  Google Scholar 

  44. Radford, A. N. Duration and outcome of intergroup conflict influences intragroup affiliative behaviour. Proc. R. Soc. B 275, 2787–2791 (2008).

    Article  PubMed  PubMed Central  Google Scholar 

  45. Clutton-Brock, T. H. Mammal Societies. (Wiley-Blackwell, 2016).

  46. Hooper, P. L., Kaplan, H. S. & Boone, J. L. A theory of leadership in human cooperative groups. J. Theor. Biol. 265, 633–646 (2010).

    Article  PubMed  Google Scholar 

  47. Vehrencamp, S. L. A model for the evolution of despotic versus egalitarian societies. Anim. Behav. 31, 667–682 (1983).

    Article  Google Scholar 

  48. Carneiro, R. L. A theory of the origin of the state. Science 169, 733–738 (1970).

    Article  CAS  PubMed  Google Scholar 

  49. Panchanathan, K. & Boyd, R. Indirect reciprocity can stabilize cooperation without the second-order free rider problem. Nature 432, 499–502 (2004).

    Article  CAS  PubMed  Google Scholar 

  50. Maynard Smith, J. & Parker, G. A. The logic of asymmetric contests. Anim. Behav. 24, 159–175 (1976).

    Article  Google Scholar 

  51. Maynard Smith, J. Evolution and the theory of games. Am. Sci. 64, 41–45 (1976).

    Google Scholar 

  52. Boyd, R. & Lorberbaum, J. P. No pure strategy is evolutionarily stable in the repeated prisoner’s dilemma game. Nature 327, 58–59 (1987).

    Article  Google Scholar 

  53. Nowak, M. A. & Sigmund, K. A strategy of win-stay, lose-shift that outperforms tit-for-tat in the prisoner’s dilemma game. Nature 364, 56–58 (1993).

    Article  CAS  PubMed  Google Scholar 

  54. Nowak, M. A. & Sigmund, K. Evolution of indirect reciprocity. Nature 437, 1291–1298 (2005).

    Article  CAS  PubMed  Google Scholar 

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

    Article  CAS  PubMed  Google Scholar 

  56. Pandit, S. A., Pradhan, G. R. & van Schaik, C. P. Why class formation occurs in humans but not among other primates: a primate coalitions model. Hum. Nat. 31, 155–173 (2020).

    Article  PubMed  Google Scholar 

  57. Hooper, P. L., Smith, E. A., Kohler, T. A., Wright, H. T. & Kaplan, H. S. Ecological and social dynamics of territoriality and hierarchy formation. in The Emergence of Premodern States: New Perspectives on the Development of Complex Societies (eds Sabloff, J. & Sabloff, P.) 105–130 (SFI Press, 2018).

  58. McNamara, J. M. & Leimar, O. Variation and the response to variation as a basis for successful cooperation. Philos. Trans. R. Soc. B 365, 2627–2633 (2010).

    Article  Google Scholar 

  59. R Core Team R: A Language and Environment for Statistical Computing (R Foundation for Statistical Computing, 2020);

  60. Marwick, B., Johnson, A., White, D. & Eff, E. A. Binford’s Hunter-Gatherer Data. R Package v. 0.1. (2016).

  61. Bürkner, P. C. brms: an R package for Bayesian multilevel models using Stan. J. Stat. Softw. 80, 29094 (2017).

    Article  Google Scholar 

  62. Ringen, E. J., Duda, P. & Jaeggi, A. V. The evolution of daily food sharing: a Bayesian phylogenetic analysis. Evol. Hum. Behav. 40, 375–384 (2019).

    Article  Google Scholar 

  63. Minocher, R., Duda, P. & Jaeggi, A. V. Explaining marriage patterns in a globally representative sample through socio-ecology and population history: a Bayesian phylogenetic analysis using a new supertree. Evol. Hum. Behav. 40, 176–187 (2018).

    Article  Google Scholar 

Download references


We thank M. Hamilton, C. Hauert, G. Wild, D. Bhat, S. Bowles, E. A. Smith, C. van Schaik and S. Gavrilets for input and feedback. P.L.H. was supported by an Omidyar Fellowship at the Santa Fe Institute.

Author information

Authors and Affiliations



P.L.H. and H.S.K. conceived the research. P.L.H. developed and analysed the model. A.V.J. analysed the empirical data. P.L.H. and A.V.J. wrote the paper.

Corresponding author

Correspondence to Paul L. Hooper.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Peer review information: Primary Handling Editor: Stavroula Kousta.

Publisher’s note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Hooper, P.L., Kaplan, H.S. & Jaeggi, A.V. Gains to cooperation drive the evolution of egalitarianism. Nat Hum Behav 5, 847–856 (2021).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing