October 17, 2008
Researchers Breathe New Life Into Classic Experiments
The recent discovery of ageing vials of chemicals in a California lab contain surviving samples from the legendary experiments performed by chemist Stanley Miller in the 1950s.
Many believe the samples provide evidence that life may have born violently, in erupting volcanoes in the midst of a thunderstorm.
At age 22, Miller was studying for his PhD when he carried out his original, groundbreaking experiments (under his University of Chicago mentor, Harold Urey).
By striking electric sparks in a mixture of gases thought to resemble the atmosphere of the young Earth, Miller wanted to test the current ideas for the origin of life.
Stanley Miller soon became an instant celebrity when his analysis of the products in the experiments revealed traces of the building blocks of life, amino acids (which combine to make proteins).
A former student, Jeffrey Bada, inherited Miller's materials when he died in May of last year. It included several boxes containing vials of dried samples from those 1950s experiments, and the accompanying notebooks.
"We started going through some of the stuff that was piled up in the corner, and here were several little cardboard boxes, taped shut and all dusty, carefully labeled with all of these little vials with dried material from his experiments," said Professor Bada, of the University of California, San Diego.
First done in 1952, Miller's well-known experiments used water along with methane, ammonia and hydrogen, the kinds of gases then thought to have dominated the Earth's oxygen-free atmosphere more than two billion years ago.
His sparks turned the mixture red, then yellow-brown, and made a number of amino acids, including glycine and alanine, commonly found in proteins.
But soon after, those conditions resembled an erupting volcano after Miller had revised the experiments by injecting hot steam into the gas mixture.
Not long after Miller's original experiments, it became clear the Earth's early atmosphere was nothing like the "reducing" mixture simulated in his apparatus.
The first experiments remained iconic in their attempt at simulating pre-biotic chemistry, but became irrelevant in detail.
But Professor Bada says conditions in volcanoes might not have been so different. The trouble was, Miller published only the sketchiest of details of those tests, and the apparatus was lost. It had looked like a dead end, until those dusty boxes turned up with their 200 vials.
"We started sorting through these, and lo and behold, we found a whole collection, almost a complete collection, of the extract samples from the volcanic experiments. And so we just went at it, using the state-of-the-art techniques we have today and analyzed these samples.
"We found not only did these make more of certain amino acids than in the classic experiment, but they made a greater diversity of amino acids."
Miller had found five amino acids using the old methods; Jeffrey Bada and his teams tracked down 22. Even better, the overall chemical yields were often higher than in the first set of experiments - the mixture appeared to be more fertile.
Today, almost all volcanic eruptions are accompanied by violent electric storms, Professor Bada said. The same could have been true on the young Earth.
"What we suggest is that volcanoes belched out gases just like the ones Stanley had used, and were immediately subjected to intense volcanic lightning.
"And so each one of those volcanoes could have been a little, local prebiotic factory. And so all of that went into making the material that we refer to as the prebiotic soup."
He believes such material could then have been washed down the flanks of volcanoes into pools or coastal bays, where the building blocks of life might have kick-started evolution.
The latest work is published in the journal Science.
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