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Evolutionary Establishment of Moral and Double Moral Standards through Spatial Interactions

Figure 3

Coexistence of moralists and immoralists for , , and , supporting the occurrence of individuals with ‘double moral standards’ (who punish defectors, while defecting themselves).

(a) Initially, at time , cooperators (blue), defectors (red), moralists (green) and immoralists (yellow) are uniformly distributed over the spatial lattice. (b) After 250 iterations, cooperators have been eliminated in the competition with defectors (as the synergy effect of cooperation is not large enough), and defectors are prevailing. (c–e) The snapshots at , , and show the interdependence of moralists and immoralists, which appears like a tacit collaboration. It is visible that the two punishing strategies win the struggle with defectors by staying together. On the one hand, due to the additional punishment cost, immoralists can survive the competition with defectors only by exploiting moralists. On the other hand, immoralists support moralists in fighting defectors. (f) After 12000 iterations, defectors have disappeared completely, leading to a coexistence of clusters of moralists with immoralists.

doi: https://doi.org/10.1371/journal.pcbi.1000758.g003