Fig. 4

Selected examples of competition between evolving populations with different D values, showing the average frequency of each population during the first 50 generations of 1000 simulated runs, with ‘hand-crafted’ environments depicted in the figure to illustrate specific situations of interest. Each plot depicts the average relative size of the 3 components within the artificial brain, with D values colour coded (D = 0 in gold, D = 0.5 in blue, D = 1.0 in green). a When the benefits of each components are very strongly skewed, both D = 0 and D = 1 values can persist as each rapidly adjusts to approximate the optimal condition. b With moderate levels of variation in B across components, a D = 1 value spreads in the population (i); with increased skew in B across components, the probability of spreading switches to D = 0 (ii) unless skew is extreme in which case D = 1 again becomes successful (a). Shifts in the probability of success for D = 1 are also associated with components having opposite signs in the B̅/C difference across components (ii)