NetNews Usenet Archive 1992 #16/NN_1992_16.iso/spool/sci/space/10920

Internet Message Format | 1992-07-29 | 11.7 KB

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Date: 29 Jul 92 12:01:12 GMT
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The following has been posted on the SKEPTIC list, and gives
interesting arguments against the improbability of the apparition
of life.
J. Pharabod
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Date:         Wed, 13 May 1992 22:38:36 CDT
From:         Thomas Faller <[e-mail]>
Subject:      Re:  Evolution and abiogenesis, part 1
X-To:         [e-mail]
To:           Multiple recipients of <[e-mail]>


I mentioned that I was going to look for arguments against the "mathematically
impossible" probabilistic models, and rather than try and argue that my set of
initial circumstances is better than anyone else's set of circumstances, I'm
going to describe positive work which, to me, shows that work on abiogenic
origins has gone farther than most suspect, and that some of the statistical
arguments are now moot in the face of the results obtained already.

I don't mean to imply that we've already created life in a test tube, but the
background work is already at an advanced state. There are still arguments
over the meaning and significance of these results, but some of these
arguments have been answered in the references already, and I'm sure that
more work has been done since.

I'm going to break this up into two parts, because I'm reading from two very
different sources, and things could get long. I'd like to hear any feedback
on this from more current scientific literature; unfortunately, I'm stuck
out here in the hinterlands and rely on magazines and books for most of my
references these days.

The first part deals with an article in the May 1992 Scientific American, by
John Horgan on page 30. The article discusses the work of Julius Rebek, Jr.,
a chemist at MIT. Rebek has been developing molecules which self-replicate,
much the same way that DNA does. He uses a simple system which duplicates
some of the features of living systems. The system is so simple, that after
a few steps, it ceases to demonstrate new qualities, but it points the way
for developing evolutionary models based on non-living molecules, which
could point the way to a better understanding of living systems.

Here's how it works, in it's present version: three amines and an ester, all
synthetic, are mixed in a chloroform solution. Each amine combines with an
ester to produce an amide, each of the three different, which will self-
replicate. That is, the amide will serve as a template for other amines and
esters to cling to, and make another amide. Thermal jostling separates
the two, and each goes on to produce more amides.

The three slightly different amides replicate at roughly the same rate, but
when irradiated with UV light, one amide mutates into a variant which
reproduces much faster than the others.
In another recent experiment, two esters and two amines were mixed to create
four different amides. Two are duplicates of the earlier experiment, one is
an even better replicant than the mutant, and one is sterile, that is, it
cannot support replication at all.
Unusually, each amide replicator can also serve as a template for the other
amides, somewhat like the "hopeful monster" idea where new species would
occasionally spring full-blown into being. However, due to the simplicity of
the system, analogies to biological theory are still pretty weak.

What I want to point out here, is that even with the simplicity of the system,
we have some of the major features of biological evolution present in a
non-biological context. It illustrates self-replication, mutation and selection
in populations, hybridization, sterile products (mules), and the passing along,
or fixing of new traits in populations. This implies that evolution is a
possible byproduct of chemical systems in general and not just biological ones.

The next article discusses successes in finding molecules which display
other processes found in living systems.

Tom Faller
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Date:         Thu, 14 May 1992 10:02:08 CDT
From:         Thomas Faller <[e-mail]>
Subject:      Re:  Evolution and abiogenesis, part 2
X-To:         [e-mail]
To:           Multiple recipients of <[e-mail]>


Okay, most of my information for this part comes from a chapter in Science
and Creationism, edited by Ashley Montagu, the article is _Creationism and
Evolutionary Protobiogenesis_, by Sidney W. Fox, at the U. of Miami. The
copyright date on the book is 1984, the article has nine pages of references
dating through 1982, but I'm sure there is more recent work out there.
I've seen some controversy about proteinoid microspheres, I've also seen
replies to that controversy on the net, but I don't have the text handy.
Please try to obtain objections from the most recent and most credible sources,
and I'll look around in the bookstores in The Big City next time I get there,
and see if I can scare up some more recent information.

It has been mentioned already that a strict definition of life is still
somewhat forthcoming, and that there is still a fuzzy border between the
living and the nonliving. Demonstrating that life-like structures can arise
under primitive-earth conditions and that they can exhibit behavior similar
to modern cells, to me, takes most of the wind out of the sails of those
who contend that abiogenesis is improbable to the point of being impossible.
We can demonstrate that structures can form which resemble fossil structures,
we can demonstrate that these structures can perform many of the duties
which modern cells need to perform, and we can demonstrate that many of the
natural processes which produce these structures will produce similar
structures under many conditions, meaning that although many types of processes
may initiate life, those which go the farthest may all produce roughly the
same product, leading towards a "molecular determinism" which standardized
the form of the first life on earth, however many times it arose, and in
however many places.

Although the author states that the experiment to produce proteinoid micro-
spheres is simple enough for high-school and college students to reproduce,
I've never done it myself, and, lacking references, don't know what conditions
are implied, although the author answers a creationist argument about the
amount of heat necessary (as low as 65 degrees C) with examples of several
likely geologic scenarios. It may be important to note that a reference to
the proceedures involved is dated 1958, implying that the experiment has had
plenty of time to gather objections, and the amount of work being done with
proteinoids implies that those objections were answered satisfactorally.

The term proteinoid was defined in 1967, and appears in Chemical Abstracts
as an indexing term then. It was coined to suggest a protein, made of amino
acids, which are not produced in the usual sense by organisms. Later usage
seems to justify the similarities between proteinoids and proteins by
classifying proteinoids under thermal proteins. Proteinoids are not the
exact equivalent of modern proteins, however. My chemistry isn't that sharp,
but some of the differences include linkages not found in modern proteins.
It is suggested that progressive replacement through intermediate stages could
have led to modern proteins, I don't have a reference for any work done on
this recently. One section of the article says that proteinoids are large
peptides made from amino acids by heat; proteins are large peptides made by
organisms from amino acids by energy from ATP. Sorry I can't get more specific
than that.

Proteinoid microspheres are near-proteins produced by polymerizing amino
acids. A main contribution is from something called trifunctional amino acids
which are found in such biologic-free samples as lunar rock, meteorites and
bacteria-free terrestrial lava. The amino acids have informational and
functional value. They order the formation of proteinoids and direct the
structure and functions of the proteinoids themselves. The ordering, or non-
randomness of the proteinoids is a function of the chemical structure of
the amino acids, and does not require external ordering, direction through
divine agencies, or extraterrestrial visitors. This has been demonstrated
in the laboratory, and is the best argument against the "probabilistic"
claims that life is a decendant of random processes.

Proteinoids form microspheres, about 10 or 20 micrometers in size. The spheres
are very uniform in size and properties. Several types of microspheres are
very resistant to conditions which would tend to dissolve them, that is, they
are not fragile, although some types are. The tougher types also exhibit
the behavior which is of biological interest. They have also been artificially
fossilized, resulting in structures very similar to naturally occurring micro-
fossils, discovered in abundance in PreCambrian rocks.

The interesting part is that proteinoid microspheres exhibit activity which is
the precursor to the activities of living cells. That is, they do many of
the actions necessary for life, but on a more limited scale than modern
living cells. This is a function of the microspheres' simplicity, but
should not detract from the fact that self-ordered proteinoids do have
biological utility.

I'm going to just mention some of the activity reported for proteinoids in
this article. I'm not going to bother referencing each experiment; that's done
rather exhaustively in the text, and I don't have the resources to check
each article. The biological activities included here have been cataloged
from different experiments; I don't know what type of proteinoids were used
for each experiment, but the overall framework seems to hang together in the
literature, by virtue of reviews of progress published every couple of years,
and subject to peer review. The article has had time to gather objections and
answer them, so I assume that there have been no irrevocable objections.

Reaction, Function or Substrate in Proteinoids

Hydrolosis
Decarboxylation
Amination    (Amine activity, not animation-motion)
Deamination
Oxidoreductions
Synthesis with ATP
   Internucleotide bonds formed
   Peptide bonds formed
Photo-activated decarboxylation
Hormonal activity

Also mentioned in the article were the following activities, I don't know to
what extent they overlap the above list.

Enzyme-like activity
Photocatalytic activity
Production of pigments
Strong indications that braided informational molecules (forerunners of DNA)
can be produced
Bioelectrical behavior, membrane potentials, spiking, oscillatory discharge
Growth by accretion
Selective permeability
Protometabolism - anabolism, catabolism
Motility - movement

and others.

This implies that we are much closer to understanding the steps to cellular
life than is commonly implied in popular accounts of abiogenic research, and
demonstrates that the probabilistic models are missing a few assumptions. The
main key here is that proteinoids should assemble themselves, and then
conduct "molecular evolution" of structure and function, until at some point,
they can be considered to be living cells. This has not been demonstrated yet,
to my knowledge, but the progress made so far shows an outline of where we
are going.
I'd be very interested to see any followups of this research in the 90's.

Tom Faller