Population Structure Induces a Symmetry Breaking Favoring the Emergence of Cooperation
Figure 1
Fraction of Cooperators as a function of the enhancement factor F.
Upper panel: Under CPD Cooperation is able to dominate on Scale-free networks (lines and circles), unlike what happens on regular structures (lines and filled squares). On exponential networks, intermediate levels of cooperation emerge, as a result of the heterogeneity of such topologies. Lower panel: Under DPD the advantage of Cs is dramatically enhanced when the same cost is evenly shared among each one's neighbors. The results were obtained for networks of 103 nodes and an average degree z = 4. As expected, abandoning the well-mixed regime leads to a break-up of neutrality for F = 2.