Theory of Early Molecular Evolution

Abstract

Anew theory of early molecular evolution is described, proceeding from original speculations to specific predictions and their confirmations. This classical cycle is then repeated generating the earliest picture of evolving Life. First, a consensus temporal order (“chronology”) of appearance of amino acids and their respective codons on evolutionary scene is reconstructed on the basis of 60 different criteria, resulting in the order: G, A, D, V, P, S, E, L, T, R, I, Q, N, K, H, C, F, Y, M, W. It reveals two fundamental features: the amino acids synthesized in experiments imitating primordial conditions appeared first, while the amino acids associated with codon capture events came last. The reconstruction of codon chronology then follows based on the above consensus temporal order, supplemented by the stability and complementarity rules first suggested by M. Eigen and P. Schuster, and on earlier established processivity rule. The derived genealogy of all 64 codons suggests several important predictions that are confirmed: Gradual decay of glycine content in protein evolution; traces of the most ancient 6-residue long gly-rich and ala-rich minigenes in extant sequences; and manifestations of a fundamental binary code of protein sequences.