Monday, October 20, 2008

Life's origin had a violent setting

A classic experiment exploring the origin of life has more than a half-century later yielded new results. New results fom the experiment show that life may have been born violently, in erupting volcanoes in the midst of a thunderstorm.

In 1953, Stanley Miller, then a graduate student of Harold Urey at the University of Chicago, put ammonia, methane and hydrogen — the gases believed to be in early earth’s atmosphere, — along with water in a sealed flask and applied electrical sparks to simulate the effects of lightning. A week later, amino acids, the building blocks of proteins, were generated out of the simple molecules.

Enshrined in high school textbooks, the Miller-Urey experiment raised expectations that scientists could unravel life’s origins with simple chemistry experiments. The excitement has long since subsided. The amino acids never grew into the more complex proteins. Scientists now think the composition of air on early earth was different from what Miller used.

Consulting Miller’s notebooks, his student Jeffrey Bada found that Miller had constructed two variations of the original apparatus. One simply used a different spark generator. The second injected steam onto the sparks.

Miller had reported that he had detected five amino acids produced by the original apparatus. Johnson’s work revealed small amounts of nine additional amino acids in those samples. In the residues from the apparatus with the steam injector, the scientists detected 22 amino acids, including 10 that had never before been identified from the Miller-Urey experiment.

Bada says the results show that the tidal pools near volcanoes, where similar conditions exist, would have been the places where the amino acids could have accumulated in concentrations, enabling more complex reactions to occur.

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