Group size n=8 and cost c=0.5. (a,b) Summary results of the last 20,000 generations for a particular set of 10 runs with within-group inequality δ=1, as a function of individual valuation vi. For each set of runs, the values are averages over individuals of rank i in all groups in the population. Values for individual runs are given by circles, the average over the 10 runs is given by a solid line. (a) Individual efforts xi for rank i. (b) Relative fertilities for individuals of rank i. (c,d) Summary results over all runs for one set of parameters. For each run, the values are averages over individuals of rank i in all groups in the population. Colours show the relevant amounts for individuals of different ranks, from the rank-1 individual at the bottom (red) to the rank-8 individual at the top (dark green). Each set of bars corresponds to a specific value of benefit b. Each bar within a set corresponds to a specific value of within-group inequality δ, from the smallest on the left (δ=0.25; low inequality) to the largest on the right (δ=4; high inequality). (c) Individual efforts xi for rank i; the height of the bar is the total group effort X*. (d) Share of reproduction for individuals of rank i.