At 09:12 PM 1/7/00 +0800, Steve wrote:
[...]
>
>SB>are you guys really sure there has actually been a "shift to space"?
>>Stephen has recently posted abstracts of articles on research being done on
>>oceanic heat vents and on bacteria found in deep-earth core samples. In
>>other words abiogenesis research is alive and well on planet earth. It
>>*would* be interesting to find extra-terrestrial life or evidence of it,
>>but I think that research is in *addition* rather than *instead of.*
>
>*Today's* bacteria are not evidence for the *origin* of life any more than
>today's vertebrates are:
>
>"The view that the Bushmen are `primitive' is like the notion that bacteria
>are primitive. One may forget that the bacteria have undergone a longer
>evolutionary history than the vertebrates." (Lewontin R.C., "Human
>Diversity", 1995, p167).
>
>Corliss, who discovered the first "oceanic heat vent" (ie. hydrothermal
>vent), believes that all the life around such vents migrated there:
>
>"Since James Corliss and others agree that current life at the vents
>probably migrated there, the thermal-vent origin of life remains a
>vague idea, lacking both conceptual details and experimental support."
>(Bradley W.L. & Thaxton C.B., "Information & the Origin of Life", in
>Moreland J.P., ed., "The Creation Hypothesis", 1994, p194)
>
>Moreover hydrothermal vents are actually a *problem* for the origin of
>life:
>
>"Stanley L. Miller and his colleague Jeffrey L. Bada are not convinced that
>deep sea hydrothermal vents could have served as the womb for the origin
>of life. They have conducted experiments which indicate that the incredibly
>hot water inside these vents (frequently exceeding 300 degrees C) would
>destroy complex organic compounds. Miller has said that if the surface of
>the early earth was a frying pan, then the deep sea hydrothermal vent was a
>fire. Norman R. Pace of Indiana University does not believe that the first
>organisms could have originated at these vents. He disagrees with James
>Corliss and hypothesizes that the archaea originated in another place,
>perhaps near the surface of the earth during a respite from the meteorite
>impacts, and then migrated to the vents." (Overman D.L., "A Case Against
>Accident and Self-Organization", 1997, p80).
>
>This is because the superheated water in hydrothermal vents would
>*destroy* any organic compounds:
>
>"Stanley Miller and Jeffrey Bada at the University of California at San
>Diego have done experiments that suggest the superheated water inside
>vents, which sometimes exceeds 572 degrees F, would destroy rather than
>create complex organic compounds. As a result, Miller actually considers
>the vents a hindrance to the origin of life." (Bradley W.L. & Thaxton C.B.,
>1994, p194)
>
This is indeed an important issue for abiogenesis. If Miller and Bada
are coreect then this presents a difficulty not just for the
hydrothermal vent scenario but also for the more traditional view
which Miller favors (i.e. discharges in atmosphere yielding amino
acids which accumulate over long times in the oceans etc.) due to
the relatively rapid circulation of the Earth's early oceans through
these vents. If, on the other hand, the vents are a source rather
than a sink, then one has a possible counter to the prevailing
current opinion that the Earth's early atmosphere was probably never
strongly reducing as was once thought.
Let me take a slight detour here. One often hears claims about how
there is some sort of "cover up" of difficulties with the origin
of life. Nothing could be further from the truth. In the above
we have two examples where Stanley Miller performed experiments
which could potentially severely undermine the current theories
on the origin of life. These two examples are (1) the experiment
Steve refers to above and (2) experiments on the slightly reducing/
neutral environments which experts now generally agree comprised
the Earth's early atmosphere. These second set of experiments I
refer to show at least a two order of magnitude decrease in yields
as well as a significant decrease in variety of amino acids produced.
We often hear these results reported by creationists and might get
the idea that they were somehow involved in the work. Actually, they
would never even know about it if Miller hadn't published the
results. This I believe shows science working the way its supposed
to work.
OK, back to Miller and Bada. This study sparked an interesting
controversy which, unfortunately, I haven't kept up with in the
past few years. I might be able to find the detailed references
if anyone is interestd. Basically, several people challenged
Miller's experiment, whether it adequately modelled hydrothermal
vent conditions. There followed several rounds of point and
counter-point. Some evidence in favor of Miller's critics is
a recent paper in <Science> by Koichiro Matsuno and his co-workers
which I just happenned to stumble across a few months ago:
Imai, E. et al.,1999. "Elongation of Oligopeptides in a Simulated
Submarine Hydrothermal System," <Science> 283, 831-833.
What Matsuno did here was very interesting. He wanted to model
not just the high temperature (he went up to 350 C) and pressure
in the vent, but also the quenching that occurs when the water
leaves the vent. What he did then was cycle between a high temp/
pressure reactor and a cooling chamber. With repeated cycling
he was able to convert amino acids into oligopeptides. He was
further able to synthesize hexaglicine from oligoglycine.
This would indicate, to me anyway, that the ball is back in
Miller's court.
Brian Harper | "If you don't understand
Associate Professor | something and want to
Applied Mechanics | sound profound, use the
The Ohio State University | word 'entropy'"
| -- Morrowitz
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