"It seems likely, then, that RNA guided the primordial synthesis of proteins, perhaps in a clumsy and primitive fashion. In this way, RNA was able to create tools-in the form of proteins-for more efficient biosynthesis, and some of these could have been put to use in the replicaiton of RNA and in the process of tool production itself."
Copyright 1989, that's 17 years ago.
Obligatory flame bait for both sides:
From what I have read of the book so far, that remark seems awfully vague and hand-waving-ish. What is the proposed rate constant for the formation of a typical strand of RNA (suitable for doing a primitive version of amino-acid-encoding) at 25 Co? Is stereoselection necessary at this point? *If* the RNA makes "a protein", what keeps that protein molecule around? What determines that the protein is "useful enough" to be immediately of benefit to the nascent "proto-cell" ?? And if it is not "useful enough", what is the feedback loop to change the RNA so it produces a useful protein...? (I.e. making useless protein not only wastes time and annoys the pig, as the saying goes, it also uses up the presumably limited supply of amino acids in the immediate vicinity.)
I suspect the *stock answer* would be--"but g_w, you don't understand. There isn't just *one* protocell--there are many millions, due to their small size and the available conditions in so many [tidal pools, clay substrates, whatever the current thinking is]. And by a wonderful, elegant, and convenient analogy to larger evolutionary model, by random chance all of the protocells that *did* waste their time in such a fashion just didn't survive; we happen to be the descendants of those that *did*TM yada yada."
Point taken--except that the above merely shows a (in one sense) "plausible mechanism", which might end up being "improbable" (when you consider the *actual odds* (whatever THAT means) of generating successful, 'eating', 'self-replicating' systems from scratch.
Can you flesh out actual rates, rate constants, concentrations of likely reactants? If not, please have the grace to admit that it is not "hard science" based on experiment, empirical results, or what not; but something a couple of steps above science fiction. A hazy model, a hypothesis, a proposed mechanism -- but not yet nailed down.
Obligatory OTHER flame-bait--I'm surprised nobody has yet issued the stern chestnut that "Evolution is NOT concerned with abiogenesis, so kindly STFU." ;-)
Cheers!
Cheers!
If not, please have the grace to admit that it is not "hard science" based on experiment, empirical results, or what not
Please, why the implied slur? I never said that we know down the last detail how things occurred, I said that current thought is that the first self-replicating molecule was RNA. I would strongly encourage all creationists not to become too invested in the absolute statement "It couldn't happen, therefore God did it by miraculous intervention!" If we make progress in the next ten years that shows the RNA world is not only plausible, but likely, the creationists who've jammed God into this gap may have some difficulties with their faith. When I believed in God I had to fight this God of the gaps tendency myself. God doesn't belong in the gaps, but should be an engineer of the processes that we may eventually discover in those gaps.
And abiogenesis doesn't really have too much to do with evolution, but it's an interesting topic. :-D The theory of evolution doesn't require abiogenesis to occur on earth, it just requires an imperfectly duplicating, self-propagating organism (from abiogenesis, extraterrestrial seeding, divine intervention, etc.)
The problem goes deeper than that. If the prebiotic chemistry was conducive to the synthesis of purines and pyrimidines then it is incompatible with the synthesis of ribose. Tough nut to crack there even with a nutcracker.