Figure 6: The Development of Codons and Translation. The primitive, ancient nucleic acids were composed only of A and T bases (a), which encode and interact with only two amino acids (R1 and R2, b). The primitive, ancient oligopeptides were physicochemically compatible with each other and may have interacted specifically with each other (c). The peptide and/or nucleic acid complexes would have become located preferentially on hydrophilic/hydrophobic surfaces, forming molecular layers.