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Science
Friday > Archives
> 1999
> May
> May 14, 1999:
Hour Two: Origins of Life
Where did life on Earth come from? Nobody really knows. | Once, a commonly held belief was that the first building blocks of life formed in a primordial soup of chemicals in an ancient, warm ocean. In a famous experiment in 1953, chemists Harold Urey and Stanley Miler cooked a flask of water, methane, ammonia, and hydrogen, and sparked it with electricity. After only a few days, Urey and Miller found fragments of amino acids -- needed to form proteins -- in the water. The experiment, many people felt, proved the old assumption.
But later research revealed that perhaps the gases Urey used in his experiment weren't as common in the early atmosphere as he had thought - and that the sheer size of the oceans might have made any amino acids formed much too dilute to form into anything useful. So how did life on Earth get started? |  | One theory holds that perhaps RNA, not DNA, was first out of the starting blocks. RNA is more reactive and fragile than DNA, but can also form more easily. Some researchers believe that perhaps today's RNA-based viruses are holdovers from early life on Earth in an RNA-based-world. Other scientists are looking deep inside the Earth at primitive organisms, called Archaea, that seem to thrive on extreme conditions, believing that perhaps they hold the clues to early planetary life.
And still others believe that life didn't really "begin" here at all - but that it had help. It might be possible, they claim, for an asteroid to have brought life from somewhere else -- perhaps Mars, perhaps from even further away -- and for that life to be responsible for every living thing on the planet today.
Listeners respond
Guests:
Paul Davies
Author, "The Fifth Miracle: The Search for the Origin and Meaning of Life"(Simon & Schuster)
Author, "About Time" (Simon & Schuster)
Visiting Professor, Physics
Imperial College, London
Adelaide, Australia
Jay Melosh
Professor, Planetary Sciences
Lunar and Planetary Laboratory
University of Arizona
Tucson, Arizona
Michael Yarus
Professor, Molecular Biology
University of Colorado
Boulder, Colorado
Books/Articles Discussed:
Related Links:
Exobiology
Nasa Exobiology Group
Astrobiology Web: Life Under Extreme Conditions
SciFri: What is Life?
SciFri: the serious search for alien life
SciFri: Martian meteorite may not show signs of life
SciFri: Extremophiles
This segment produced by:
Karin Vergoth
Web producer:
Charles Bergquist
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