From: LARRY KLAES (ljk4@msn.com)
Date: Thu Apr 25 2002 - 08:47:11 PDT
HOW LIFE ORIGINATED IN SPACE
Remarks from Jon Richfield on report by Natalia Reznik via Andrew Yee
<ayee@nova.astro.utoronto.ca>
Hi Benny
A quick note concerning: HOW LIFE ORIGINATED IN SPACE (CCNet, 23 April 2002)
Some readers may be familiar with some of my fulminations on related
subjects during the past few years, and decided that I was unregenerately
resistant to the idea of extraterrestrial life. This is incorrect. For what
it is worth, I expect that there is life of sorts elsewhere in the universe
and that it will have certain correspondences and resemblances to life on
Earth. Whether its frequency is likely to be once per planet in the
biosphere, once per solar system, once per million stars, once per galaxy,
or what, I don't know. There are too many gross uncertainties and I wish we
could devote just point zero one percent of our global budget to related
studies! What gets my goat is a number of incorrect assumptions and
untenable deductions that tend to be associated with such discussions.
I am sceptical about life on Mars and even more sceptical about any of it
getting to Earth and practically dismissive about its having established
itself here if ever it did arrive, either as the origin of Earthly life, or
as a component of Earthly life.
But I am listening...
Meanwhile, E.A. Kuzicheva and N.B.Gontareva from St Petersburg have
apparently produced 5'-AMP under conditions of hard vacuum and UV in the
presence of lunar soil. This is of course interesting, but why they think it
is relevant to the problem, is unclear. If there were no
source of such an important molecule on earth, then maybe it would be more
exciting, but many purine and pyrimidine derivatives have been produced in
circumstances believed to resemble prebiotic terrestrial conditions. The
terrestrial product would have exceeded the input from
space by vast factors.
Terrestrial chemosynthetic products of a far greater variety than those from
space could arise readily and plentifully in our seas and ground water. But
that is not by any means the most important point.
Remember the fact (frequently, though irrelevantly, harped on by
creationists) that to expect combinatorial generation of the substances
needed for functional life is totally unrealistic, and to expect the
generation of living structures is beyond fantasy, even if we filled the
known universe solid with candidate molecules. If one thing is pretty near
certainty, it is that life on Earth originally developed by natural
selection, through complementary interaction of candidate substances. This
would raise the process from stochastic to a cumulatively heuristic
status. (Assuming of course, that neither the chariots of the gods nor
meteorites simply delivered life ready packaged.)
Now, such candidate substances may have been present in space as well as on
Earth, but in space the desiccated, irradiated, isolated molecules were
largely stuck where they originated. On Earth they could move, meet and
interact dynamically, either in solution or adsorbed onto the controlling
and organising surfaces of minerals. The huge rate and range of such
interactions over periods of millions or hundreds of millions of years was
almost certainly vital to the emergence of life. It involved forms of
natural selection practically from the development of the first candidate
biomolecules. Even if we were to accept the concept of the Wickramasinghe
muddy comet, which is a reasonable reaction to this form of argument, that
would not make much difference; suppose the comet were far from the sun --
it would be frozen, so that molecular migration and interaction would for
practical purposes be prevented. On the other hand, if it is frequently
near enough to the sun to melt, it will be desiccated within a few hundred
thousand years. Not a very promising cradle of life, compared to the bulk,
activity and duration of the young planet!
I have a few other niggles with the reports from Russia, though they are
lukewarm in comparison to the foregoing.
>On the Earth the reaction goes in the solution, but there are no
solvents whatsoever in space, therefore the researchers dried them in the
air and got a pellicle. <
"Dried them in the air"??? That already leaves us with serious questions as
to the relevance to the conditions in space. I wonder whether such a
"pellicle" would have developed in a vacuum. Usually vacuum drying gives a
very fine, almost molecular powder, rather than coherent pellets with
well-defined surfaces (if that is what the translator meant by this use of
the word "pellicle".) Also, reaction with various atmospheric gases could
have changed the initial conditions in all sorts of relevant ways. I don't
wish to niggle unreasonably, but I would need more detailed reassurance
than I have time to listen to, before the validity of this procedure would
satisfy me.
"...and the researchers used the lunar soil, delivered to the Earth
by the 'Moon-16' station from the Sea of Abundance, as a model of the
comet, meteorite, interplanetary or cosmic dust. The soil represented
basaltic dust..."
This is not a logical objection, but I don't see why lunar dust should have
been any more interesting in this experiment than ground ancient basalt from
Earth. In fact I should be interested to see a control experiment. My
money says that the two should show very little difference in outcome.
"...It has appeared that a small pinch of the lunar soil protects
organic substances from the destructive ultraviolet impact -- the lunar
soil helps to increase the 5'-AMP yield by 2.7 times."
Again, what is so special about the lunar soil? I do not suggest that the
investigators stated that it was in fact special, but putting it like that
makes it sound as though it was the lunar nature of the soil that did the
trick. If that was in fact what they intended, then control runs with
terrestrial basalt would be in order.
>The researchers have made a conclusion that the organic compounds
synthesis could have happened in the outer space environment. The
synthesis could have taken place on the surface of space bodies at
the initial phases of the solar system formation, along with that the
chemical evolution (formation and selection of complex molecules) could have
started in space.<
This is not at issue. All the way back to Oparin, Miller and Urey, this
would have been unexciting.
>By the time the Earth was formed the chemical evolution might have
approached the phase to be followed by the biological evolution.
That implies that life on the Earth most probably did not start from
the elementary organic molecules synthesis, but commenced from the
polymers formation phase or from a further stage. <
Here the wheels come off with a grinding thump. First of all, the amazing
thing about the first emergence of life on Earth is not how fast the first
candidate biochemicals emerged; a few hours, weeks or even millions of years
would be neither here nor there. The breathtaking (and exciting) thing is
how quickly the complex, functional structures emerged, and as I have said,
it is grossly implausible that they could have emerged in space, either in
muddy comets or in desiccated "pellicles". More or less random polymers
form prolifically on Earth and any traces arriving from space are extremely
unlikely to have contributed anything of importance.
Also, how many such pellicles or functionally equivalent structures have
been found on meteorites in or form space? Are our pellicles relevant to
what goes on out there?
Interesting work of course, and I doubt that such an informal report covers
it adequately, but even so, it does not sound like a fundamental new
insight into probable mechanisms of abiogenesis.
Cheers,
Jon
"Marriage has many pains, but celibacy
has no pleasures." -- Samuel Johnson
Additional information about the conference,
http://www.ssq.net/Coming_Events/Paris/paris.html
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