The role of mutations, addition of amino acids and exchange of genetic information in co-evolution of primitive coding systems

The standard genetic code (SGC) is a crucial system for encoding biological information but its evolution remains still unresolved and is a topic of debate. Thus, we used a methodology based on the evolutionary algorithm to investigate the emergence of stable coding systems. The simulation started with a population of various primitive genetic codes, which encoded ambiguously only a small number of amino acids (labels). These codes were subjected to a selection process for the accuracy of reading genetic information and increasing coding potential as well as mutation modelled by the changing assignment of the labels to codons, the stepwise introduction of new amino acids into the codes and the exchange of information between the co-evolving coding systems. The evolution converged towards stable and unambiguous coding systems with the higher coding capacity necessary for the production of more diversified proteins. An important factor was the exchange of the encoded information between the evolving codes, which substantially shortened the simulation time to produce the genetic codes encoding 21 labels. The findings highlight key factors that may have shaped the structure of the current genetic code.