Area54,
Thanks again for your reply. Here's my two cents to your two cents.
You say >> I believe you are asking the wrong question <<
Interesting choice of words: I believe there are great questions, better questions and good questions - but I've never thought about what a "wrong" question is. Hmmm. (Are there "bad" questions as well???)
You say >>
However, if I understand you, you suggest there IS no answer to this question, because...
... inferring that the environment of the primeval earth, which would likely be vastly different than today's, is not available for research. (And maybe, not necessarily a more measured question?)
My personal hunch about this is, yes, the primeval world was so un-imaginably different than today's, and may have in fact been exuding / producing massive quantities of nucleotide precursors. In which case, there would be no need for extra-terrestrial assistance. In which case, the RNA world theory gets further support.
However, before I naively presume that the earth was somehow naturally (and pre-biotically) producing scads of RNA monomers, I thought I'd ask this forum if anybody was aware of any evidence on TODAY'S earth, where this was in fact actually happening. To date, I've found no information that contends that it is occurring. (Which doesn't necessarily prove that it isn't though).
Regarding your comment about extra-terrestrial sugars: What bothers me about the idea of pre-biotic "seeds" arriving on earth via asteroids and meteors, is that all of these vehicles had to pass through the atmosphere first, and be subjected to horrendous temperatures. Small meteorites would probably completely vaporize. Only very large ones would make to the earth's surface with their interiors not scorched and um, thermally readjusted. But if they made it this far, they'd next have to contend with contacting either liquid or solid surfaces, at hyper-sonic speeds - which also would not likely be hospitable to the organic chemicals that survived re-entry.
And I could be totally wrong about this. Maybe there were in fact zillions of Goldilocks-sized meteorites falling to earth, and maybe the pre-biotic atmosphere wasn't that inhospitable, yadda yadda. But ultimately, IMHO, it would make for a simpler story, if there was an identified mechanism in place on earth, or one that could be fairly easily imagined.
My hope is that, should we ever make it to Titan and Enceladus, we'll discover geo-thermal chemistry going on that will make our scientific eyes pop out of our simian heads. Chemistry that we'll be able to infer very-likely happened on earth as well. My hope.
Thanks again for your reply.
Jeff