The present analysis comes to the conclusion that the sets of canonical amino acids and bases as well as the genetic triplet code were largely complete at the level of LUCA. The Wong coevolution theory of the genetic code has been discussed in detail. The literature comprises numerous proposals concerning the origin of translation and other aspects of the genetic machinery. A review of all these proposals and many others is beyond the scope of the present paper. The present paper is a research paper and not a review paper. It aims at a comprehensive account of early evolution from the origin of life all the way to LUCA. This puts a systematic constraint on literature selection. An effort (unfortunately fallible) has been made to include all those references that integrate with the main lines of the present account into a coherent account. Contributions by others that have the character of theoretical modules that fit well into this account have been termed “theorems” with names of the main authors attached. A reference to a paper on nucleotide biosynthesis phylogeny is now cited in Section 7.
Therefore, my comments will be slanted by my own expertise and will only serve the author as a partial devil’s advocate effort General commentary