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Social diversity promotes the emergence of cooperation in public goods games


Humans often cooperate in public goods games1,2,3 and situations ranging from family issues to global warming4,5. However, evolutionary game theory predicts4,6 that the temptation to forgo the public good mostly wins over collective cooperative action, and this is often also seen in economic experiments7. Here we show how social diversity provides an escape from this apparent paradox. Up to now, individuals have been treated as equivalent in all respects4,8, in sharp contrast with real-life situations, where diversity is ubiquitous. We introduce social diversity by means of heterogeneous graphs and show that cooperation is promoted by the diversity associated with the number and size of the public goods game in which each individual participates and with the individual contribution to each such game. When social ties follow a scale-free distribution9, cooperation is enhanced whenever all individuals are expected to contribute a fixed amount irrespective of the plethora of public goods games in which they engage. Our results may help to explain the emergence of cooperation in the absence of mechanisms based on individual reputation and punishment10,11,12. Combining social diversity with reputation and punishment will provide instrumental clues on the self-organization of social communities and their economical implications.

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Figure 1: Population structure and local neighbourhoods.
Figure 2: Evolution of cooperation in networked PGGs.
Figure 3: Dynamics on the double star.
Figure 4: Wealth distribution.


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F.C.S. acknowledges support from Fonds de la Recherche Scientifique, Belgium. M.D.S. and J.M.P. acknowledge financial support from Fundação para a Ciência e Tecnologia, Portugal.

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Correspondence to Jorge M. Pacheco.

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Santos, F., Santos, M. & Pacheco, J. Social diversity promotes the emergence of cooperation in public goods games. Nature 454, 213–216 (2008).

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