Letter | Published:

Conjoining uncooperative societies facilitates evolution of cooperation

Nature Human Behaviourvolume 2pages492499 (2018) | Download Citation


Social structure affects the emergence and maintenance of cooperation. Here, we study the evolutionary dynamics of cooperation in fragmented societies, and show that conjoining segregated cooperation-inhibiting groups, if done properly, rescues the fate of collective cooperation. We highlight the essential role of intergroup ties, which sew the patches of the social network together and facilitate cooperation. We point out several examples of this phenomenon in actual settings. We explore random and non-random graphs, as well as empirical networks. In many cases, we find a marked reduction of the critical benefit-to-cost ratio needed for sustaining cooperation. Our finding gives hope that the increasing worldwide connectivity, if managed properly, can promote global cooperation.

Access optionsAccess options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Additional information

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


  1. 1.

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

  2. 2.

    Simpson, B. & Willer, R. Beyond altruism: sociological foundations of cooperation and prosocial behavior. Annu. Rev. Sociol. 41, 43–63 (2015).

  3. 3.

    Hauert, C. & Doebeli, M. Spatial structure often inhibits the evolution of cooperation in the snowdrift game. Nature 428, 643–646 (2004).

  4. 4.

    Lieberman, E., Hauert, C. & Nowak, M. A. Evolutionary dynamics on graphs. Nature 433, 312–316 (2005).

  5. 5.

    Ohtsuki, H., Hauert, C., Lieberman, E. & Nowak, M. A. A simple rule for the evolution of cooperation on graphs and social networks. Nature 441, 502–505 (2006).

  6. 6.

    Szabó, G. & Fath, G. Evolutionary games on graphs. Phys. Rep. 446, 97–216 (2007).

  7. 7.

    Débarre, F., Hauert, C. & Doebeli, M. Social evolution in structured populations. Nat. Commun. 5, 3409 (2014).

  8. 8.

    Allen, B. et al. Evolutionary dynamics on any population structure. Nature 544, 227–230 (2017).

  9. 9.

    Centola, D. The spread of behavior in an online social network experiment. Science 329, 1194–1197 (2010).

  10. 10.

    Centola, D. & Macy, M. Complex contagions and the weakness of long ties. Am. J. Sociol. 113, 702–734 (2007).

  11. 11.

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

  12. 12.

    Jordan, J. J., Rand, D. G., Arbesman, S., Fowler, J. H. & Christakis, N. A. Contagion of cooperation in static and fluid social networks. PLoS ONE 8, e66199 (2013).

  13. 13.

    Rand, D. G., Nowak, M. A., Fowler, J. H. & Christakis, N. A. Static network structure can stabilize human cooperation. Proc. Natl Acad. Sci. USA 111, 17093–17098 (2014).

  14. 14.

    Long, J. C., Cunningham, F. C. & Braithwaite, J. Bridges, brokers and boundary spanners in collaborative networks: a systematic review. BMC Health Serv. Res. 13, 158 (2013).

  15. 15.

    Fischer, C. S. Toward a subcultural theory of urbanism. Am. J. Sociol. 80, 1319–1341 (1975).

  16. 16.

    Wellman, B. The Persistence and Transformation of Community: from Neighbourhood Groups to Social Networks. Report to the Law Commission of Canada (Wellman Associates, 2001).

  17. 17.

    Burt, R. S. Structural Holes: The Social Structure of Competition (Harvard Univ. Press, Cambridge, MA, 2009).

  18. 18.

    Rosenthal, E. Social networks and team performance. Team Perform. Manag. 3, 288–294 (1997).

  19. 19.

    Watts, D. J. Networks, dynamics, and the small-world phenomenon. Am. J. Sociol. 105, 493–527 (1999).

  20. 20.

    Benkler, Y. The Penguin and the Leviathan: How Cooperation Triumphs over Self-interest (Crown Business, New York, NY, 2011).

  21. 21.

    Ansell, C., Bichir, R. & Zhou, S. Who says networks, says oligarchy? Oligarchies as "rich club" networks. Connections 35, 20–32 (2016).

  22. 22.

    Burt, R. S. Neighbor Networks: Competitive Advantage Local and Personal (Oxford Univ. Press, Oxford, 2010).

  23. 23.

    Fracassi, C. Corporate finance policies and social networks. Manag. Sci. 63, 2420–2438 (2016).

  24. 24.

    Heemskerk, E. M. & Takes, F. W. The corporate elite community structure of global capitalism. New Political Econ. 21, 90–118 (2016).

  25. 25.

    Crane, D. Social structure in a group of scientists: a test of the "invisible college" hypothesis. Am. Sociol. Rev. 34, 335–352 (1969).

  26. 26.

    Zhou, S. & Mondragón, R. J. The rich-club phenomenon in the internet topology. IEEE Commun. Lett. 8, 180–182 (2004).

  27. 27.

    Davis, G. F. The significance of board interlocks for corporate governance. Corp. Gov. Int. Rev. 4, 154–159 (1996).

  28. 28.

    Kranton, R. E. & Minehart, D. F. A theory of buyer-seller networks. Am. Econ. Rev. 91, 485–508 (2001).

  29. 29.

    Rocha, L. E., Liljeros, F. & Holme, P. Information dynamics shape the sexual networks of internet-mediated prostitution. Proc. Natl Acad. Sci. USA 107, 5706–5711 (2010).

  30. 30.

    Erdös, P. & Rényi, A. On random graphs. Publ. Math. 6, 290–297 (1959).

  31. 31.

    Klemm, K. & Eguiluz, V. M. Growing scale-free networks with small-world behavior. Phys. Rev. E Stat. Nonlin. Soft Matter Phys. 65, 057102 (2002).

  32. 32.

    Lancichinetti, A., Fortunato, S. & Radicchi, F. Benchmark graphs for testing community detection algorithms. Phys. Rev. E Stat. Nolin. Soft Matter Phys. 78, 046110 (2008).

  33. 33.

    Parker, J. G. & Asher, S. R. Friendship and friendship quality in middle childhood: links with peer group acceptance and feelings of loneliness and social dissatisfaction. Dev. Psychol. 29, 611–621 (1993).

  34. 34.

    Anderson, C. J., Wasserman, S. & Crouch, B. A p* primer: logit models for social networks. Soc. Netw. 21, 37–66 (1999).

  35. 35.

    Zachary, W. W. An information flow model for conflict and fission in small groups. J. Anthropol. Res. 33, 452–473 (1977).

  36. 36.

    Coleman, J. S. et al. Introduction to Mathematical Sociology (London Free Press, Glencoe, IL, 1964).

  37. 37.

    Girvan, M. & Newman, M. E. Community structure in social and biological networks. Proc. Natl Acad. Sci. USA 99, 7821–7826 (2002).

  38. 38.

    Ohtsuki, H. & Nowak, M. A. Direct reciprocity on graphs. J. Theor. Biol. 247, 462–470 (2007).

  39. 39.

    Reiter, J. G., Hilbe, C., Rand, D. G., Chatterjee, K. & Nowak, M. A. Crosstalk in concurrent repeated games impedes direct reciprocity and requires stronger levels of forgiveness. Nat. Commun. 9, 555 (2018).

  40. 40.

    Olejarz, J., Ghang, W. & Nowak, M. A. Indirect reciprocity with optional interactions and private information. Games 6, 438–457 (2015).

  41. 41.

    Willer, D. Network Exchange Theory (Praeger Publishers, Westport, CT, 1999).

  42. 42.

    Wang, Z., Szolnoki, A. & Perc, M. Optimal interdependence between networks for the evolution of cooperation. Sci. Rep. 3, 2470 (2013).

  43. 43.

    Wang, Z., Szolnoki, A. & Perc, M. Interdependent network reciprocity in evolutionary games. Sci. Rep. 3, 1183 (2013).

  44. 44.

    Jiang, L.-L. & Perc, M. Spreading of cooperative behaviour across interdependent groups. Sci. Rep. 3, 2483 (2013).

  45. 45.

    Wang, Z., Szolnoki, A. & Perc, M. Rewarding evolutionary fitness with links between populations promotes cooperation. J. Theor. Biol. 349, 50–56 (2014).

  46. 46.

    Battiston, F., Perc, M. & Latora, V. Determinants of public cooperation in multiplex networks. New J. Phys. 19, 073017 (2017).

  47. 47.

    Tarnita, C. E., Ohtsuki, H., Antal, T., Fu, F. & Nowak, M. A. Strategy selection in structured populations. J. Theor. Biol. 259, 570–581 (2009).

Download references


This work was supported by the James S. McDonnell Foundation (B.F.), NSF grant 1715315 (B.A.) and the John Templeton Foundation (M.A.N.). The funders had no role in study design, data collection and analysis, decision to publish or preparation of the manuscript. B.F. thanks S. Rytina for insightful and stimulating conversations.

Author information


  1. Program for Evolutionary Dynamics, Harvard University, Cambridge, MA, USA

    • Babak Fotouhi
    • , Naghmeh Momeni
    • , Benjamin Allen
    •  & Martin A. Nowak
  2. Institute for Quantitative Social Sciences, Harvard University, Cambridge, MA, USA

    • Babak Fotouhi
  3. Massachusetts Institute of Technology (MIT) Sloan School of Management, Cambridge, MA, USA

    • Naghmeh Momeni
  4. Department of Mathematics, Emmanuel College, Boston, MA, USA

    • Benjamin Allen
  5. Center for Mathematical Sciences and Applications, Harvard University, Cambridge, MA, USA

    • Benjamin Allen
  6. Department of Mathematics, Harvard University, Cambridge, MA, USA

    • Martin A. Nowak
  7. Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA, USA

    • Martin A. Nowak


  1. Search for Babak Fotouhi in:

  2. Search for Naghmeh Momeni in:

  3. Search for Benjamin Allen in:

  4. Search for Martin A. Nowak in:


All authors contributed to all aspects of the paper.

Competing interests

The authors declare no competing interests.

Corresponding author

Correspondence to Babak Fotouhi.

Supplementary information

  1. Supplementary Information

    Supplementary Methods, Supplementary References

  2. Reporting Summary

About this article

Publication history