Hydrothermal origin of life?
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.
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.
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.
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.
The team leader, Koichiro Matsuno, was quoted as follows:
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.
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’ 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.”’]
- 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.