Frozen Evolution. Or, that’s not the way it is, Mr. Darwin. A Farewell to Selfish Gene.

The existence of a correlation between similarity or relatedness of aminoacids and similarities of the corresponding codons can be interpreted in two ways.To begin with, this can be considered to demonstrate that the genetic code underwent a phase of evolutionand that this evolution was governed by the principles described in the coevolutionary or stereochemical hypothesis of the formation of the genetic code.

            However, there is also another interpretation.The fact that mutually similar aminoacids are encoded by mutually similar triplets could be an advantageous adaptation to the existence of mutations and errors occurring during transcription and translation(Woese 1965; Di Giulio 2000).If a substitution mutation occurs in the gene or if an error occurs in its transcription or translation, the substituted protein will most probably contain an aminoacid similar to the original one in the substituted locus (a conservative substitution will occur).Consequently, there will most probably not be a substantial change in the structure and the biological properties and thus in the functioning of the relevant protein.