Figure 4.

Identical beard colour altruism levels over evolutionary time. The data from the experiment plotted in figure 1e are shown here across evolutionary time. Plotted is the average number of donation instructions per type executed per organism for each update. The plot shows averages over 50 evolutionary trials (±1 s.e.). The altruism level of identical beard colour targeting rises early and remains at a high level for most of the experiment, which lasted thousands of generations. Purple, kin; light blue, random; grey, neutral; black, similarity (85%); red, identical beard colour.