According to Charles Carter, a forty-year expert in ancient biology, the hypothesis that RNA preceded DNA in the origin of life is, by itself,
” … extremely unlikely,” said Carter. “It would take forever.”
Moreover, there’s no proof that such ribozymes even existed billions of years ago. To buttress the RNA World hypothesis, scientists use 21st century technology to create ribozymes that serve as catalysts. “But most of those synthetic ribozymes,” Carter said, “bear little resemblance to anything anyone has ever isolated from a living system.”
He proposes, instead, Urzymes or “molecular fossils,”and he reports that he has constructed something like them in the lab:
The finding also suggests that Urzymes evolved from even simpler ancestors—tiny proteins called peptides. And over time those peptides co-evolved with RNA to give rise to more complex life forms.
In this “Peptide-RNA World” scenario, RNA would have contained the instructions for life while peptides would have accelerated key chemical reactions to carry out those instructions.
…
The study leaves open the question of exactly how those primitive systems managed to replicate themselves—something neither the RNA World hypothesis nor the Peptide-RNA World theory can yet explain.
Well, that’s this year’s model.