In article <1992Aug17.132342.29191 at s1.gov>, lip at s1 (Loren I. Petrich) writes:
> it is much more difficult to make nucleotides, though it can
>be done by rather contrived experiments. I have seen serious
>speculation that RNA was a "takeover" from another self-replicating
>molecule that was probably simpler.
Cairns-Smith's GENETIC TAKEOVER, involving clays as the precursor, is
well-known. I've also come across Joyce, Schwartz, Miller, Orgel "The
case for an ancestral genetic system involving simple analogues of the
nucleotides" PNAS 84, p4398 (Jul 1987). They argue the case that
acyclic analogues to the usual nucleosides were the original genetic
material (or at least pre-RNA). Any others?
-Matthew P Wiener (weemba at sagi.wistar.upenn.edu)