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.

Conjoining uncooperative societies facilitates evolution of cooperation


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.

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

Relevant articles

Open Access articles citing this article.

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: From spite to cooperation by conjoining cliques.
Fig. 2: Super-promoters of cooperation.
Fig. 3: Rich clubs and bipartite graphs.
Fig. 4: Conjoining random graphs and empirical networks.


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

    Article  PubMed  PubMed Central  Google Scholar 

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

    Article  Google Scholar 

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

    Article  PubMed  CAS  Google Scholar 

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

    Article  PubMed  CAS  Google Scholar 

  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).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

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

    Article  Google Scholar 

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

    Article  PubMed  CAS  Google Scholar 

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

    Article  PubMed  CAS  Google Scholar 

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

    Article  PubMed  CAS  Google Scholar 

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

    Article  Google Scholar 

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

    Article  Google Scholar 

  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).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

  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).

    Article  PubMed  CAS  Google Scholar 

  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).

    Article  PubMed  PubMed Central  Google Scholar 

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

    Article  Google Scholar 

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

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

    Article  Google Scholar 

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

    Article  Google Scholar 

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

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

    Article  Google Scholar 

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

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

    Article  Google Scholar 

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

    Article  Google Scholar 

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

    Article  Google Scholar 

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

    Article  Google Scholar 

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

    Article  Google Scholar 

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

    Article  Google Scholar 

  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).

    Article  PubMed  Google Scholar 

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

    Google Scholar 

  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).

    Article  PubMed  CAS  Google Scholar 

  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).

    Article  CAS  Google Scholar 

  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).

    Article  Google Scholar 

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

    Article  Google Scholar 

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

    Article  Google Scholar 

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

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

    Article  PubMed  CAS  Google Scholar 

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

    Article  PubMed  PubMed Central  Google Scholar 

  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).

    Article  PubMed  PubMed Central  CAS  Google Scholar 

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

    Article  Google Scholar 

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

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

    Article  PubMed  PubMed Central  Google Scholar 

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

    Article  PubMed  PubMed Central  CAS  Google Scholar 

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

    Article  PubMed  PubMed Central  Google Scholar 

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

    Article  PubMed  Google Scholar 

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

    Article  Google Scholar 

  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).

    Article  PubMed  Google Scholar 

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

Authors and Affiliations



All authors contributed to all aspects of the paper.

Corresponding author

Correspondence to Babak Fotouhi.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

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

Supplementary information

Supplementary Information

Supplementary Methods, Supplementary References

Reporting Summary

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Fotouhi, B., Momeni, N., Allen, B. et al. Conjoining uncooperative societies facilitates evolution of cooperation. Nat Hum Behav 2, 492–499 (2018).

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