2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/96959Information theoretic analysis of genetic languages indicates that the naturally occurring 20 amino acids and the triplet genetic code arose by duplication of 10 amino acids of class-II and a doublet genetic code having codons NNY and anticodons $\overleftarrow{\rm GNN}$. Evidence for this scenario is presented based on the properties of aminoacyl-tRNA synthetases, amino acids and nucleotide bases.10 pages (v2) Expanded to include additional features, including likely relation to the operational code of the tRNA-acceptor stem. Version to be published in Journal of Theoretical BiologyGenomicsComputational Engineering, Finance, and ScienceBiomoleculesQuantum Physicstext