Re: Logic Gives But One Choice On OOL. Can any find another?

On Mar 3, 6:22 pm, Guy A Hoelzer <hoel...@xxxxxxx> wrote:
in article fqeu0n$156...@xxxxxxxxxxxxxxxxxxx, Tom Hendricks at
tom-hendri...@xxxxxxx wrote on 3/2/08 11:09 AM:

On Feb 28, 12:49 pm, verulam <johnhewit...@xxxxxxxxx> wrote:
Tom,
OK, you feel the nucleotide problem can be solved but I do not agree.
I think nucleotides can only arise as part of an established
metabolism, which is a "metabolism first" viewpoint.

"Metabolism first' is a fluke chemical event. Now when metabolism pops up is
it immediately adapted to the environment, or is it destroyed in that
environment? if not adapted immediately, we need another fluke. That's two, -
you'll need about 10 more before your'e done. And one is enough to rule out
life.

Tom,

I would count myself in the metabolism-first camp, and I think you are
missing the point of this view. The emergence of a metabolism de novo is no
more of a fluke event than the emergence of a convection cell in the
atmosphere. You could argue that a convection cell is initially spawned by
a fluke puff of wind that entrains the emergence of a full blown dissipative
structure, but that would also miss the point. Like a convection cell, a
metabolism does thermodynamic work. The structure of a dissipative
metabolism is fueled by local gradients (e.g., macromolecular structures,
thermal gradients, and so on) and could be sparked by chaotic chemical
dynamics (analogous to a puff of wind sparking a convection cell). I
wouldn't call chemical dynamics a metabolisms until positive feedback loops
are established, which effectively sustain the structure of the metabolic
chemistry (again, analogous to positive feedback within a convection cell).

In other words, the metabolisms-first view envisions the prior existence of
a physical potential (e.g., a thermal and/or macromolecular gradient) that
pulled dynamic metabolic (chemical) structures into existence. This is
different from a fluke.

Cheers,

Guy

Yes, I would agree with Guy's comments here - at least insofar as they
apply to the mechanism for the origin of a metabolism advanced by
myself.

The point is that one can describe *an* origin for metabolism that
begins, essentially, with just our present perception of the
prebiotic earth and some standard physical and organic chemistry. You
then that the resulting, thermally driven oscillations would be
subject to selective evolution. By considering how you might expect
that evolution to progress, you can get something resembling
metabolism to emerge. That is not a "Pop and adapt" view and I have no
idea how Tom comes by the notion.

By contrast Tom is, himself, assuming that nucleotides will simply pop
into existence and then defy chemistry by behaving in whatever way he
finds convenient. I don't think so but I cannot put the responsibility
entirely on Tom. Currently, the most popular theory for the origin of
life is the "RNA world" theory and that entire program does exactly
what Tom is doing.

Sincerely

John Hewitt

.

Relevant Pages

  • Re: Minimum Cell?
    ... 'reproduction' and metabolism. ... (activated nucleotides) ... to produce multimers in modern transmembrane proteins. ... But any model of abiogenesis would ...
    (talk.origins)
  • Re: Logic Gives But One Choice On OOL. Can any find another?
    ... metabolism, which is a "metabolism first" viewpoint. ... chemistry. ... By contrast Tom is, himself, assuming that nucleotides will simply pop ...
    (sci.bio.evolution)
  • Re: Logic Gives But One Choice On OOL. Can any find another?
    ... you feel the nucleotide problem can be solved but I do not agree. ... metabolism, which is a "metabolism first" viewpoint. ... "Metabolism first' is a fluke chemical event. ... You could argue that a convection cell is initially spawned by ...
    (sci.bio.evolution)
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