  The poly-tRNA model was recently presented for the origin and evolution of
genetic coding. This model has led to a rather precise description of what
might have occurred at the beginning of protein synthesis in the first life
form. Here, we further discuss some interesting implications of this model.
First, the system of encoded peptide/protein synthesis appears to have started
and developed on the breeding ground of a rich RNA world, responsible for the
infancy of life existence and complexity. Furthermore, once protein synthesis
was fully established and apparently superseding the RNA world, and at a very
early stage of life beginnings, we already see what has been a recurrent theme
in the likely interpretation of modern comparative molecular studies on
species: the full ability of this nascent life entity to develop itself by
tinkering, using all kinds of available pieces to improve itself. Lastly, and
very instructively, it is deduced from this model that the first peptides to be
produced probably had unique properties, not shared by the arsenal of molecules
present hitherto, which allowed a functional connection between the then
omnipotent RNA world and the lipid membrane vesicles containing it. These
specific functions might have initially been at the origin of the Darwinian
selection of the full-blown protein-synthesis machinery.
