Re: No Grace Period for Metabolism Either

From: Catherine Woodgold (an588_at_freenet.carleton.ca)
Date: 11/12/04 

Date: Fri, 12 Nov 2004 22:27:40 +0000 (UTC)

tinyurl.com/uh3t (rem642b@Yahoo.Com) writes:
> I think it's more likely that some random replicator came first, then
> it polymerized, which yielded a very primitive genome, and later it
> evolved to produce enzymes, and later one of those enzymes aided
> replication by pattern, and later the original polymer was replaced by
> RNA or DNA or polypeptides, and if not DNA then later it was replaced
> by DNA. At each replacement event, the parasitic replacement out-bred
> its parent species, driving it to extinction, removing all evidence of
> the parent that we could see today, so the only evidence we see today
> (including the fossil record for the past 3500 million years) is the
> final generation in this sequence, the DNA generation.

Oh, OK. That's starting to sound more plausible.
However, I would point out that we still see RNA as well
as DNA. It might be possible to make an argument that
the original polymer would not have died out, because
it would probably have had some advantages/uses.

Perhaps until a specific plausible example of an alternative
polymer is suggested, I'll continue to imagine that it
may well have been RNA.

One difference between your description and mine is that
I'm assuming the RNA, at first, didn't actually create
nucleotides, but just influenced the joining of them
together into certain patterns.

Hmm -- perhaps that suggests an alternative hypothesis:
something other than RNA joined into polymers and
catalysed some more stuff to join into similar polymers,
without actually catalysing the creation of that
other stuff.

It seems to me to be simpler and easier for Life to
have begun by using building blocks that were already
there, rather than doing the work of creating them.

If huge quantities of some substance were created, it
seems to me more plausible that it was created by
ordinary chemical processes, not replication. 

--
Cathy

Relevant Pages

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