Here we suggest that the origin of the genetic code, that is to say, the birth of first mRNAs has been triggered by means of a widespread modification of all RNAs (proto-mRNAs and proto-tRNAs), as today observed in the RNA editing and in post-transcriptional modifications of RNAs, which are considered as fossils of this evolutionary stage of the genetic code origin. We consider also that other mechanisms, such as the trans-translation and ribosome frameshifting, could have favoured the transition from an ennuplet code to a triplet code. Therefore, according to our hypothesis all these mechanisms would be reflexive of this period of the evolutionary history of the genetic code.
