Hydrothermal origin of life?
by Jonathan Sarfati
Some Japanese researchers have claimed to prove that life could have arisen in a
submarine hydrothermal vent. However, the most complex molecule their ‘simulation’
produced was hexaglycine, in the microscopic yield of 0.001%. Compared to the complexity
of even the simplest living cell, hexaglycine is extremely simple. High temperatures
would degrade any complex molecules over the alleged geological time.
Introduction
The simplest possible cell, according to recent theoretical analysis, would need
a bare minimum of 256 genes coding for the required enzymes, which are long polypeptides.
And it is doubtful whether such a hypothetical organism could survive, because such
an organism could barely repair DNA damage, could no longer fine-tune the ability
of its remaining genes, would lack the ability to digest complex compounds, and
would need a comprehensive supply of organic nutrients in its environment.1
One major difficulty is linking up the building blocks at all, let alone in the
right sequence. This is because thermodynamic considerations show that long molecules
like proteins and nucleic acids tend to break up into their component monomers (amino
acids and nucleotides respectively).2
Any undirected energy input is more likely to be destructive rather than constructive,
like ‘a bull in a china shop’, and to increase the variety of undesirable
side reactions possible.
Hydrothermal vents
Some researchers have proposed that life began in submarine hydrothermal vents,
where superheated subterranean water pours into the sea. The idea is that the heat
can help synthesize polymers, which would then be quenched in the surrounding sea
water—this would prevent the same energy from destroying the products soon
after they were formed.
Five researchers in Nagaoka, Japan, claimed to have simulated such conditions in
a flow reactor.3 They circulated 500
ml of a strong solution of glycine (0.1 M) through several chambers at a high pressure
of 24.0 MPa. The first chamber was heated mainly to 200–250 ° C; from
there, the liquid was injected at the rate of 8–12 ml/min into a cooling chamber
kept at 0 ° C. Then the liquid was depressurized before samples were extracted
at various intervals. The whole cycle was completed in 1–1.3 hours. In some
of the runs, 0.01 M CuCl2 was added to the 0.1 M glycine solution, which
was also acidified to pH 2.5 by HCl at room temperature.
Experimental results
The most spectacular results occurred in the runs with the extra CuCl2
and HCl. The Cu2+ ions catalyzed the formation of tetraglycine (yield
0.1%). Even some hexaglycine formed (yield 0.001%). But the product with the highest
yield was the cyclic dimer, diketopiperazine, which peaked at about 1% yield, then
dropped. The reader is not informed as to how much effort was invested in optimizing
the conditions to maximize the amount of larger polyglycines.
Assessment
The team leader, Koichiro Matsuno, was quoted as follows:
‘For 10 years, underwater hydrothermal vents have been thought to be the place
where life began—and we were able to prove it.’
4
But is this justified by the experimental results? No! As shown by the following
reasons, Matsuno’s claim is based on evolutionary faith, which results in
over-optimistic interpretation of the data.
-
The concentration of glycine of 0.1 M was far higher than could be expected in a
real primordial soup. In reality, prebiotic simulations of glycine production produce
far lower yields. Also, any glycine produced would be subject to oxidative degradation
in an oxygenic atmosphere. Or else, if there was a primitive oxygen-free atmosphere,5 the lack of an ozone layer would
result in destruction by ultraviolet radiation. Also, adsorption by clays, precipitation
or complexation by metal ions, or reactions with other organic molecules would reduce
the concentration still further. A more realistic concentration would be 10–7
M.6
-
While the hydrothermal conditions might be right for this experiment, overall, they
would be harmful in the long term to other vital components of life. For example,
the famous pioneer of evolutionary origin-of-life experiments, Stanley Miller, points
out that polymers are ‘too unstable to exist in a hot prebiotic environment’.7 Miller has also pointed out that
the RNA bases are destroyed very quickly in water at 100 ° C — adenine
and guanine have half lives of about a year, uracil about 12 years, and cytosine
only 19 days.8 Intense heating also
readily destroys many of the complex amino acids such as serine and threonine.9 Another problem is that the exclusive
‘left-handedness’ required for life is destroyed by heating, i.e. the
amino acids are racemized.10
But this was not put to the test because the Japanese team used the simplest amino
acid, glycine, which is the only achiral amino acid used in living systems. It seems
incomprehensible that after designing this experiment with such care other amino
acids would not have been tested. The fact that they are all known to undergo various
non-peptide bond reactions has surely not escaped the researchers’ attention.
-
The longest polymer (or rather, oligomer) formed was hexaglycine. Most enzymes,
however, have far more than six amino acid residues—usually hundreds. And
even the hexaglycine produced was found only in minuscule amounts.
-
This experiment gave a simple homo-oligomer, i.e. all monomers are the same. But
life requires many polymers in precise sequences of 20 different
types of amino acids. Thus Matsuno’s experiments offer not the slightest explanation
for the complex, high-information polymers of living organisms.
Conclusion
As the non-creationist information theorist Hubert Yockey observed over 20 years
earlier (and he has not revised his opinion since):
‘Research on the origin of life seems to be unique in that the conclusion
has already been authoritatively accepted … . What remains to be done is
to find the scenarios which describe the detailed mechanisms and processes by which
this happened.
One must conclude that, contrary to the established and current wisdom a scenario
describing the genesis of life on earth by chance and natural causes which can be
accepted on the basis of fact and not faith has not yet been written.’ 11
[Update: recent research shows more difficulties with this idea: Darwin’s warm pond idea is tested, 13
February 2006:
‘David Deamer, emeritus professor of chemistry at the University of California
at Santa Cruz, said ahead of his presentation: “It is about 140 years since
Charles Darwin suggested that life may have begun in a ‘warm little pond’.
‘“We are now testing Darwin's idea, but in ‘hot little puddles’
associated with the volcanic regions of Kamchatka (Russia) and Mount Lassen (California,
US).
‘“The results are surprising and in some ways disappointing. It seems
that hot acidic waters containing clay do not provide the right conditions for chemicals
to assemble themselves into ‘pioneer organisms’.”
‘Professor Deamer said that amino acids and DNA, the “building blocks”
for life, and phosphate, another essential ingredient, clung to the surfaces of
clay particles in the volcanic pools.
‘“The reason this is significant is that it has been proposed that clay
promotes interesting chemical reactions relating to the origin of life,” he
explained.
‘“However,” he added, “in our experiments, the organic compounds
became so strongly held to the clay particles that they could not undergo any further
chemical reactions.”’]
Related articles
References
- Wells, W., Taking life to bits, New Scientist
155(2095):30–33, 1997. Return to text.
- Sarfati, J.D.,
Origin of life: the polymerization problem, CEN Tech.
J. 12(3):281–284, 1998. Return to text.
- Imai, E., Honda, H., Hatori, K., Brack, A. and Matsuno, K., Elongation
of oligopeptides in a simulated submarine hydrothermal system, Science
283(5403):831–833, 1999. Return to text.
- Matsuno, K.; cited by Elaine Lies, Reuters Nagaoka, Japan, Feb.
5, 1999. Return to text.
- The ‘strongest evidence’ for an anoxic ancient earth
atmosphere is that we know chemical evolution took place, and this would have been
impossible with oxygen present! The following ‘reason’ in this circular
way: Walker, J.C.G., Evolution of the Atmosphere, Macmillan, NY, p. 224,
1977; Fox, S. and Dose, K, Molecular Evolution and the Origin of Life,
W.H. Freeman & Co., San Francisco, pp. 45–45, 1972; cited in:
Thaxton et al., Ref. 6. Return to text.
- Thaxton, C.B., Bradley, W.L. and Olsen, R.L., The Mystery of
Life’s Origin, Philosophical Library Inc., New York, ch. 4, 1984.
Return to text.
- Miller, S.L. and Lazcano, A., The origin of life—did it occur
at high temperatures? J. Mol. Evol. 41:689–692,
1995. Return to text.
- Levy, M and Miller, S.L., The stability of the RNA bases: Implications
for the origin of life, Proc. Natl. Acad. Sci. USA 95(14):7933–38,
1998. Return to text.
- Gish, D.T., Origin of life: The Fox
thermal model of the origin of life, Impact 33, Institute
for Creation Research, March 1976. Return to text.
- Sarfati, J.D.,
Origin of life: the chirality problem, CEN Tech. J.
12(3):263–266, 1998. Return to text.
- Yockey, H.P., A calculation of the probability of spontaneous
biogenesis by information theory, J. Theor. Biol. 67:377–398,
1977; quotes from pp. 379, 396. Return to text.
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