Life uses 20 coded amino acids (CAAs) to construct proteins. This set was likely evolutionarily ‘standardized’ from smaller sets as organisms discovered how to make and encode them. Scientists modeled how the adaptive properties of the CAAs evolved over time. They found that sets containing even only a few CAAs were better than an enormous choice of alternatives, suggesting each time a modern CAA was discovered, it bootstrapped the set to include still more CAAs.
Source: Scientists find biology’s optimal ‘molecular alphabet’ may be preordained: The amino acids, a fundamental set of life’s building blocks, may have been adaptive throughout their evolution, suggesting a possible universal biological language. — ScienceDaily