News about how life on Earth may have begun in volcanoes.
Below article from The New York Times reprinted for fair use purposes only -- copyright acknowledged.
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The New York Times
Copyright 1998 The New York Times
July 31, 1998
Experiment Supports Theory That Life Began in Volcanic Environment
By NICHOLAS WADE
The idea that life on Earth began in the furnace-like temperatures of a volcanic environment has received support from an experiment designed to reconstruct the chemical events that may have led to
the first living cells.
The experiment, reported in Friday's issue of the
journal Science, shows that peptides, short protein chains, can form
naturally under conditions that might plausibly have existed on the early Earth some four billion years ago.
Dr. Carl R. Woese of the University of Illinois, a
microbiologist who believes that life may have begun at high emperatures like those found near volcanoes and in the undersea vents where magma gashes through the ocean floor, described the result as "another step in the grand march."
But a dash of cold water was thrown by Dr. Stanley Miller of the University of California at San Diego, a leading advocate of the view that life evolved at temperatures similar to those of today.
The chief author of the experiment, a new voice indiscussions of the
origin of life, was Dr. Gunther Wachtershauser. Although his day job is as a patent lawyer in Munich, Germany, Wachtershauser (pronounced
VEK-terz-hoi-zer) has a degree in organic chemistry, and his papers have been accepted by leading scientific journals.
The prevailing idea about the origin of life is that prebiotic chemistry -- the chemical reactions that led to the first livingcell -- probably occurred in some kind of watery environment. As a graduate student in 1953, Miller provided striking evidence for thistheory by showing that many chemicals used by living cells will formnaturally from a mixture of water and gases subjected to electrical discharges that mimic lightning.
But it has proved very hard to take Miller's classic experiments much
further. The problem is that a pinch of chemicals inwatery solution do not bump into one another often enough to create themore complicated molecules of life.
Wachtershauser has developed a quite different concept: that prebiotic reactions occurred not in solution but on a surface,
probably of some common catalyst like the ores of iron and nickel.
Chemicals bound to a surface would be much more likely to meet and combine into the more complicated molecules typical of life, he believes. In other words, prebiotic chemistry started in 2-D, and only later did the first systems escape into three dimensions.
With a government grant and the help of a chemist colleague, Dr. Claudia Huber of the Munich Technical University,Wachtershauser has been conducting a series of experiments to test theelements of his theory.
Last year he showed that an active, carbon-based chemistry could get
started in a simple mixture of iron ore, nickel and the volcanic gases hydrogen sulfide and carbon monoxide. In their latestpaper, he and Dr. Huber show that in similar conditions, amino acids,the building blocks of today's proteins, can make the characteristic linkknown as a peptide bond that forms the backbone of proteins. In theconditions of their experiment, chains of two and three amino acids wereassembled in a novel chemical reaction, they report.
This experiment started with amino acids already in the mixture. It
showed, however, that had amino acids formed underthese conditions,
they could go on to form peptide bonds. Amino acidsformed in space are thought to have been delivered to the early Earth bymeteorites and comets. Wachtershauser is also trying to show howamino acids might have been generated under volcanic conditions.
Dr. Norman Pace, an expert on early life at the University of California at Berkeley, said the new reaction showed that it is relatively easy to make biological compounds from inorganic chemicals. "Wachtershauser's concept of mineral-based chemistry being able to generate biologically active compounds is wonderful," Pace said. "I think the milieu of a geothermal environment is far superior to the sparking bottles of Stanley Miller."
Miller remains unconvinced by the proponents of a high-temperature
origin of life. He has a forceful objection: Many of the essential
components of living cells are unstable at high temperatures. In a paper published this month in The Proceedings of the National Academy of Sciences, he reported that constituents of DNA lasted as little as 19 days at the temperature of boiling water.
"We conclude that a high-temperature origin of life may be possible, but it cannot involve adenine, uracil, guanine orcytosine," he wrote with a touch of acerbity, referring to four of the five main components of the nucleic acids DNA and RNA.
In Wachtershauser's theory, however, the nucleic acidsare a late
adornment of the system. "In the oldest days," he said, "all the molecules of life participated in the reproduction and inheritance process, and it is only later that the nucleic acids became enthroned."
Miller also said that carbon monoxide, an important ingredient of
Wachtershauser's experiments, was not known to be produced by deep-sea vents and that an earlier report to the contrary was based on an
Woese, of the University of Illinois, said he considered this "a minor drawback compared with the drawbacks of the soup theory," the soup in question being the watery environments in which Miller
seeks the origin of life.
"Since all this chemistry that Wachtershauser works with is novel," Woese said, "we have to cut him a little slack rather
than close the door on it immediately."
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