Re: OOL Interlude - The Relevance of Biochemistry
- From: Tim Tyler <tim@xxxxxxxxxxx>
- Date: Sun, 10 Apr 2005 16:53:51 -0400 (EDT)
Perplexed in Peoria <jimmenegay@xxxxxxxxxxxxx> wrote or quoted:
> Comparative biochemistry is crucial to an informed approach to OOL.
IMO, biochemistry is practically irrelevant to the origin of life.
You would not agree - since you have adopted a very strage position
that apparently insists that an explanation for the origin of life
must explain everything up to the MRCA. With *that* definition of the
origin of life, biochemistry is indeed very important.
However that is not how most people would define life's origin.
Adopt their position for a moment - and consider that a mineral
origin of life would makes biochemistry of /very/ low relevance -
due to the near-complete lack of carbon atoms.
The chemistry that *I* think has turned out to be the most relevant
is that of layer silicates and metal oxides - the world of crystal
formation - alas, a totally foreign land to most OOL researchers :-(
> This information takes us back only to the MRCA. But if we have
> an incorrect model of the MRCA, then we are likely to construct an
> incorrect model of the RNA world, and this will probably lead to
> an incorrect model of the original OOL.
The RNA world happened *long* after the OOL - and condideration
of the RNA world played practically no role in the discovery of
how life originated, except by way of its prebiotic implausibilty.
It is not clear to me why you think a model of the RNA world
necessarily has anything to do with the origin of life.
> There is just no way that we can construct a believable model of some
> "isolated" part of this evolutionary process without simultaneously
> looking at all other parts.
....unless it so happens that certain parts of that process could
only have realistically happened one way.
If life must pass through certain checkpoints or "bottlenecks"
in its passage to the stars, we may be able to use these to
identify some aspects of its path.
Perhaps we will be lucky - and one of the bottlenecks will
coincide with the origin of life. If so, we have a chance
of finding out how life formed. If we are *very* lucky there
may be multiple such "bottlenecks" - in which case we might get
more than one piece of the early story of life - and if we get
enough such pieces /maybe/ we can start threading them together.
Life's mineral origin and a genetic takeover are examples
of candidate bottlenecks. Other candidate bottlenecks
include the formation of the first cells, the invention
of sex, the invention of chlorophyll, the invention
of genetic engineering - and so on.
If there's a convincing bottleneck, we don't have to look
much further - we know something about what happened,
without further consideration of the evolutionary
history that led up to it or the consequences that
followed from it. If we can do that, we can confidently
predict that life elsewhere must have followed a similar path.
This is essentially the position taken in "Life's Solution" -
that convergent evolution has substantial power - and that
consequently, some things in the evolutionary process are
sure things.
IMO, without the existence of such bottlenecks, progress
in uncovering the *actual* path our most distant ancestors
most likely took will inevitably be very difficult for a
very long time.
--
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- OOL Interlude - The Relevance of Biochemistry
- From: Perplexed in Peoria
- OOL Interlude - The Relevance of Biochemistry
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