Outcomes of selection on the fermentation yield of proto-codes randomly initiated with equal probabilities of glycine, alanine, valine and aspartic acid. For each of these amino acids (first column) the mean of the final number of anticodons that coding (second column) and the average of the G+U content of the assigned anticodons (third column). The fourth column is the p-value from a sign test centred at 1.5 (the expected mean number go G+U in a randomly constructed codon). The distribution of assignments are significantly different from 1.5. Pearson's χ2 test on a binomial distribution was also applied, and in all cases resulted in p-values between 10-15 and 10295. These test reject the null hypothesis, i.e. the structure of the proto-codes cannot be explained by random assignments. The data consists of the end points of 104 independent runs, each evolved for 60,000 generations (MC steps).