> While I'm certainly no expert on the subject, I have read extensively
> from the literature. As partial evidence of this, I'll provide
> below what would arguably qualify for one of the
> five examples I asked for. BTW, one reason I asked
> for five and not just one is that I already had one :-).
I welcome this constructive way forward in this exchange. I have to
say that I have nothing to add to Brian's list. However, I have
started reading Thomas Gold's "The deep hot biosphere" (Some may
remember that I posted a copy of a review of this book a while ago).
This book has far more on abiogenesis than I had thought and my notes
on the first chapter are below. Gold's views are, in my opinion, of
considerable interest.
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For abiogenesis to occur, there must be an environment that favours
the formation of different combinations of precursor organic
molecules.
"For life forms to arise and persist, molecules must be
awash in a liquid or a gas, so that gentle contacts among molecules
can build up other molecules and generate a brew of the kind of
complexity we find in biological materials. In all of the expressions
of life known to us, this mobility is provided by liquid water. Given
the ferocious and unfriendly conditions of the universe - with points
of intense heat and vast expanses of severe cold - one would think it
rare indeed for any place to hold surface temperatures in the range
that would render water a liquid." (page 3).
So rare would it be that Gold calls it a "far-fetched fantasy in this
forbidding universe. And yet we know of one such place: our little
earth." (page 4).
Gold points out that the earliest self-replicating structures must
have been able to draw energy from their environment and convert it to
chemical energy. The process of photosynthesis is crucial to the
survival of surface life forms.
"When we consider life's beginning, however, we realize that a puzzle
lurks in this account of energy transformation. Photosynthesis is an
extremely complex process. The microorganisms that developed it must
have already possessed intricate chemical processing systems before
they acquired this more advanced ability. The energy source that
these initial microorganisms drew on must have been chemical to begin
with. The chemical energy available before the advent of
photosynthesis could not have been created by solar energy or by
life. It must have been a free gift of the cosmos." (page 5).
Gold recognises that photosynthesis is so complex, that it cannot have
arisen spontaneously. It must have evolved. (Some might wish to
challenge this, and argue that photosynthesis is an example of
irreducible complexity - but Gold does not consider that possibility).
Gold's proposal is that the energy for the earliest life was derived
from the oxidation of hydrocarbons deep in the earth's crust.
He develops the concept of a "metred supply of energy" as crucial for
any theory of life's origin. This, in his view, rules out the surface
of our planet (and so relegates the work of Miller, Fox and other
researchers of surface processes to the box labelled 'unviable'.)
"The often-discussed warm little pond that contained nutrients forged
with great difficulty by surface processes is not a candidate
environment, in my opinion, for the transition from non-life to life.
Such an environment would yield a limited amount of chemical
supplies and energy, not a long-term and continuous metred supply.
What is needed, rather, is an environment that can supply chemical
energy in a metred flow over tens or hundreds of millions of years,
during which time incomprehensibly large numbers of molecular
experiments might take place" (page 7).
Gold is clearly of the view that the 'origin of life' problem has not
been solved. He says that "the two most profound mysteries of the
biological sciences" are "the origin of earth life and the prospects
for extraterrestrial life". (page 9).
Interestingly, he comments:
"In retrospect, it is not hard to understand why the scientific
community has typically sought only surface life in the heavens.
Scientists have been hindered by a sort of "surface chauvinism.""
(page 8). Gold recognises that scientists are operating within
conceptual frameworks (paradigms) which have the effect of restricting
their horizons of interest. He is clearly of the view that the bulk of
the abiogenesis research has been unfruitful as a direct consequence
of this tunnel vision.
---------------------------
Can I conclude by saying something similar to Brian - if it is true
that the abiogenesis research community is of the opinion that life
has been produced in the lab, then I would like to see evidence of
this. I do want to know. All the research that I read about is
still seeking to solve fundamental problems, and it seems to me that
this is exactly how people like Thomas Gold and Paul Davies (whose
new book I have recently commented on) read the literature. If these
fundamental problems have been solved, why are the researchers
keeping it so quiet!
Best regards,
David J. Tyler.