are; however, we find no relation between activity in the forum and cooperation. These results suggest that the public … feeling of community supports the cooperation in that provision. …

formation of within-group cooperation is affected by different types and degrees of between-group interactions. We show that … when between-group interactions are of the same directions and weak (strong), within-group cooperation for providing public … the opposite directions or unidirectional, within-group cooperation will necessarily occur. In addition, endogenous …

Sometimes cooperation between two parties requires exactly one to cede to the other. If the decisions whether to cede … a two-player cooperation game enhances cooperation. Although subjects cede less overall with the waiting option, we show …

Gratuitous cooperation (in favour of non-relatives and without repeated interaction) eludes traditional evolutionary …, conformism and gratuitous cooperation co-evolve, and group selection is a necessary ingredient for the co-evolution to take place …-mutations (e.g., the rare emergence of a charismatic leader that brings order to the group) are necessary to sustain cooperation in …

conformists dramatically increases the group size for which cooperation can be sustained. The results of our model are robust …