TomHendricks474  wrote or quoted me writing:

>> RNA could /only/ hold the key to the origin of life /if/ it was the 
>> first replicator.
>> 
>> However, RNA is high technology - extremely unlikely to be pre-biotically 
>> plausible - and thus can't realistically have had anything to do with
>> the origin of life - since it was a later invention, and represents a 
>> product of natural selection.
>
> Could you back that up with some studies or
> references, or specific arguments?

The best explanation I'm aware of regarding why RNA is not a sensible
candidate for the first replicator is in the first part of:

Genetic takeover - and the mineral origins of life, A. G. Cairns-Smith, 
Cambridge University Press, 1982;

However much the same sentiment has been expressed by others - e.g.:

``But where did RNA come from? To date, no one has been able to form RNA
  under in the laboratory under conditions that mimic those believed to
  have existed on primitive Earth. Some scientists also question whether
  nucleic acids with a backbone of ribose, or any other sugar molecule,
  would be stable enough to survive the harsh conditions of early Earth.

  So it is generally agreed that RNA must have evolved from an earlier
  form. While TNA is a good candidate, other polymers that exhibit
  self-replication and base pairing could have evolved into RNA.
  Pyranosyl RNA (p-RNA) and peptide nucleic acid (PNA) are two of
  these alternatives. [...]''

 - http://nai.arc.nasa.gov/news_stories/news_detail.cfm?ID=189

RNA seems /particularly/ unlikely as the first replicator - since
its replication is blocked by isomeric impurities in its bases -
as described by J. Maynard Smith on p. 73 of "The Major Transitions
in Evolution".
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