Mesoscopic Structure Conditions the Emergence of Cooperation on Social Networks

• DOI: 10.1371/journal.pone.0001892
• Publication Date: 2008-04-01T20:42:40Z
• Authors: Sergi Lozano; Alex Arenas; Angel Sánchez
• Keywords: Physics - Physics and Society; Design; Matemáticas; Science; FOS: Physical sciences; Physics and Society (physics.soc-ph); Social Environment; Models, Biological; 01 natural sciences; Origin; Game Theory; Residence Characteristics; General Mathematics (math.GM); 0103 physical sciences; FOS: Mathematics; Humans; Computer Simulation; Interpersonal Relations; Cooperative Behavior; Quantitative Biology - Populations and Evolution; Mathematics - General Mathematics; Condensed Matter - Statistical Mechanics; Mathematical Physics; 97; Substrates; Statistical Mechanics (cond-mat.stat-mech); Communities; Q; R; Populations and Evolution (q-bio.PE); Social Support; Mathematical Physics (math-ph); Computational Physics (physics.comp-ph); Biological Evolution; Nonlinear Sciences - Adaptation and Self-Organizing Systems; FOS: Biological sciences; Medicine; Physics - Computational Physics; Adaptation and Self-Organizing Systems (nlin.AO); Research Article

Background We study the evolutionary Prisoner's Dilemma on two social networks substrates obtained from actual relational data. Methodology/Principal Findings We find very different cooperation levels on each of them that cannot be easily understood in terms of global statistical properties of both networks. We claim that the result can be understood at the mesoscopic scale, by studying the community structure of the networks. We explain the dependence of the cooperation level on the temptation parameter in terms of the internal structure of the communities and their interconnections. We then test our results on community-structured, specifically designed artificial networks, finding a good agreement with the observations in both real substrates. Conclusion Our results support the conclusion that studies of evolutionary games on model networks and their interpretation in terms of global properties may not be sufficient to study specific, real social systems. Further, the study allows us to define new quantitative parameters that summarize the mesoscopic structure of any network. In addition, the community perspective may be helpful to interpret the origin and behavior of existing networks as well as to design structures that show resilient cooperative behavior.<br/>ISSN:1932-6203<br/>PLoS ONE, 3 (4)<br/>