Self-Description and the Origin of the Genetic Code

Abstract: The genetic code presents an important conceptual challenge within the broader context of the origin of life. Translation of genetic information captures a fundamental property of living systems, i.e. ability of decoding proteins (e.g. aminoacyl-tRNA synthetases) to reproduce themselves from self-contained RNA/DNA descriptors. Silvano Colombano and I, as graduate students with Howard Pattee in the 70's, focused on achieving this closure of self-description and self-reproduction in the genetic code. Simulation and analysis of competitive models that allowed alternate code assignments, exploring initial conditions, arbitrary descriptor-catalyst relationships, and degree of non-linearity, indicated that these dynamical systems undergo bifurcations, transforming initial ambiguous stable states to unstable ones. New, stable steady states, progressively closer to a code, became available as the descriptor parameters were varied. The efficiency of utilization of raw materials for the production of a coding family of catalysts is proposed as a selection criterion that drives such systems towards a coded state.

Keywords: origin of genetic code, coded system, self-describing system, aminoacyl-tRNA synthetase, protocell