Aminoacyl-tRNA synthetases (aaRSs) are responsible for creating the pool of correctly charged aminoacyl-tRNAs that are necessary for the translation of genetic information (mRNA) by the ribosome. Each aaRS belongs to either one of only two classes with two different mechanisms of aminoacylation, making use of either the 29OH (Class I) or the 39OH (Class II) of the terminal A76 of the tRNA and approaching the tRNA either from the minor groove (29OH) or the major groove (39OH). Here, an asymmetric pattern typical of differentiation is uncovered in the partition of the codon repertoire, as defined by the mechanism of aminoacylation of each corresponding tRNA. This pattern can be reproduced in a unique cascade of successive binary decisions that progressively reduces codon ambiguity. The deduced order of differentiation is manifestly driven by the reduction of translation errors. A simple rule can be defined, decoding each codon sequence in its binary class, thereby providing both the code and the key to decode it. Assuming that the partition into two mechanisms of tRNA aminoacylation is a relic that dates back to the invention of the genetic code in the RNA World, a model for the assignment of amino acids in the codon table can be derived. The model implies that the stop codon was always there, as the codon whose tRNA cannot be charged with any amino acid, and makes the prediction of an ultimate differentiation step, which is found to correspond to the codon assignment of the 22nd amino acid pyrrolysine in archaebacteria.
Granted, this is a few years old, but I often find myself having to admit that "I don't know" when at the root of discussions on evolution. That is, once abiogenesis has occurred, we can go on and explain the rich diversity of life, but sadly we really don't know much before that critical step. Generally, those satisfied with "magic" as an answer posit their myths and fables, whereas I'd rather try to actually find out what happened. Sadly, as the abstract shows, you actually need a level of education to understand papers such as this that is generally well beyond those who would deny the reality of evolution.
Does anyone have a collection of papers on abiogenesis that are more accessible and understandable to laypeople?