Different World, Different Organisms?
This discussion suggests that much of the
history of life on earth is due to a particular sequence of events that could
have happened differently. It is
tempting to ask what would have happened if key aspects of evolution on Earth
had been different:
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What if water weren't the solvent, and
the common elements were not C, H, N, O, P and S? Could life (a self-replicating entity of any form) evolve?
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What if life had evolved on land
instead of in the ocean?
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What if a different genetic code had
appeared in the first self-replicators?
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What if gravity were greater (or less)?
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What if different materials were
available for use by organisms?
-
What if there had been a different
pattern or timing of mass extinctions?
Would life as we know it have evolved the
same way? One would suspect that the
trajectory of evolution would have been very different. Would Eukaryotes have
even evolved?
It remains to be seen whether traces of life,
present or past, will be found in other worlds. From this discussion, it seems likely that if signs of
self-replication are found elsewhere, the forms of life may be very different
than those seen on our planet. Our
challenge may be not only to locate extraterrestrial life, but to recognize it.
Contributed by: Dr. Sara Via
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