PMC

The nested tug-of-war. Individuals engage in a selfish tug-of-war over resource shares within groups, and, simultaneously, groups engage in a tug-of-war with each other. The within-group tug-of-war reduces a group's ability to win the between-group tug-of-war.

Fractional investment in group competitiveness. (Upper) Individual's evolutionarily stable investment in group competitiveness (equals the degree of superorganismness) as a function of between group relatedness (r′) and within-group relatedness (r) (n = 100; n = 4; z = w). (Lower) Individual's evolutionarily stable investment in group competitiveness as a function of group size (n) and number of competing groups (N) (r′ = 0; r = 1/2; z = w).