The panspermia hypothesis only pushes back the question of how life originated.
The panspermia hypothesis is the hypothesis that the first organisms on Earth came into existence elsewhere in the universe and were transported to the Earth by natural means, for instance by hitching a ride on a comet or meteor.
I. May work in combination with other hypotheses
Although panspermia would not in itself explain the origin of life, it would put a larger number of possible explanations on the table. Some environments may be more hospitable to a spontaneous origin of life than the environment of the early Earth; for instance, Stanley Miller's striking early experiments with prebiotic synthesis presupposed a reducing atmosphere, but the actual atmosphere of the early Earth now appears to have been oxidizing. Panspermia is one way the gap might be bridged between the results of such experiments and the conditions of early earth, as it could allow life to have originated in a reducing atmosphere elsewhere before making its way to Earth.
II. Nevertheless premature at the moment
It should be pointed out that panspermia is only one avenue under investigation. Most scientists still think there is plenty of room for the origin of life to have occurred on Earth. With this said, some researchers take very seriously the related idea that a significant amount of prebiotic synthesis (but not the origin of life itself) took place in outer space, and that resultant chemicals important to the origin of life were delivered to the Earth by meteorites or comets. Since important prebiotic chemicals have indeed been detected in interstellar gas clouds and on meteorites (Olomucki 1993:46), such proposals are not far-fetched, though their ultimate plausibility still is debated.
Olomucki M. 1993. The Chemistry of Life. New York: McGraw-Hill.
Last update: 12 Jan 2015
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