Has thew genetic code evolved on the stereochemical complementarity between aminoacids and correspondent anti-codon? Or is it a frozen accident? Or is it the result of the coevolution of aminoacid anabolism and codon usage?
Check out the altest paper by Yarus and co-workers.
Turk-Macleod RM, Puthenvedu D, Majerfeld I, Yarus M.
The plausibility of RNA-templated peptides: simultaneous RNA affinity for adjacent peptide side chains.
J Mol Evol. 2012 Apr;74(3-4):217-25.