a Repeat of the first Origin of life Experiments

A Repeat of the first Origin of Life Experiment

In 1953 Stanley Miller, a chemist at the University of Chicago, along with his colleague Harold Urey, used a sparking device to mimic a lightning storm on early Earth. Their experiment produced a brown broth rich in amino acids, the building blocks of proteins. The disclosure made the pages of national magazines and showed that theories about the origin of life could actually be tested in the laboratory. The results of this famous experiment suggested that Earth's early atmosphere could have produced chemicals necessary for life - contradicting the view that life's building blocks had to come from comets and meteors.

Images: courtesy of Dept. of Chemistry & Biochemistry, University of California, San Diego

Chemist Jeffrey Bada, of the Scripps Institute of Oceanography in La Jolla, Calif. is revisiting the famous experiment first done by his mentor, Stanley Miller. "Maybe we're over-optimistic, but I think this is a paradigm shift," in Origins of Life research says Bada. After their famous experiment the Miller-Urey results were later questioned: It turns out that the gases he used (a reactive mixture of methane and ammonia) did not exist in large amounts on early Earth. Scientists now believe the primeval atmosphere contained an inert mix of carbon dioxide and nitrogen—a change that made a world of difference.

When Miller himself, repeated the experiment using the correct combo in 1983, the brown broth failed to materialize. Instead, the mix created a colorless brew, containing few amino acids. It seemed to refute a long-cherished icon of evolution—and creationists quickly seized on it as supposed evidence of evolution's wobbly foundations.

However, Bada's repeat of the experiment—armed with a new insight—seems likely to turn the tables once again. Bada discovered that the reactions were producing chemicals called nitrites, which destroy amino acids as quickly as they form. They were also turning the water acidic—which prevents amino acids from forming. Yet primitive Earth would have contained iron and carbonate minerals that neutralized nitrites and acids. So Bada added chemicals to the experiment to duplicate these functions. When he reran the experiment, he still got the same watery liquid as Miller did in 1983, but this time it was chock-full of amino acids. Bada presented his results the last week of March, 2007 at the American Chemical Society annual meeting in Chicago.

Christopher McKay, a planetary scientist at NASA Ames Research Center in Moffett Field, California said the repeat experiment is important for it's a move toward more realism in terms of what the conditions actually were on early Earth.

Many Origin of Life researchers believe that the origin of life depended heavily on chemicals delivered to Earth in Panspermic-like events by comets and meteorites. The repeat of Miller's experiments if viable could shift the paradigm back said Christopher Chyba, an astrobiologist at Princeton University. "That would be a terrific result for understanding the origin of life," he says, "and for understanding the prospects for life elsewhere."

Bada's experiment could also have implications for life on Mars, because the Red Planet may have been swaddled in nitrogen and carbon dioxide early in its life. Bada intends to test this extrapolation by doing experiments with lower-pressure mixes of those gases.