Genotype-phenotype maps for the ancestral organisms used in this study. Each row represents one instruction, starting from the first instruction in the organism’s genome (top row) to the final instruction (bottom row). Each column represents one of the logic functions performed by the ancestor. The color of each cell indicates what happens to the performance of a function when the instruction in that row is knocked out (replaced with a null instruction). White: knocking out the instruction does not affect performance of the function. Gray: knocking out the instruction causes the function to be lost. (A) Map for Ancestor1. Note that every instruction that knocks out OR also knocks out EQU, but the reciprocal is not true. (B) Map for Ancestor2. Note that every instruction that knocks out either AND or OR also knocks out EQU.