From: Twirlip of Greymist (phoenix@ugcs.caltech.edu)
Date: Thu Aug 08 1996 - 17:07:09 MDT
On Aug 8, 10:22am, Robin Hanson wrote:
} Subject: Mars life implications
} Anyone else out there find it improbable that life evolved from
} nothing to complex single-cells in the few hundred million years after
} the earth and mars cooled enough to support life? Seems more likely
} to me that life evolved more leisurely elsewhere and came here.
No*. Mammals have come a long way in 65 million years. Multicellular
went a long way in possibly 20 million years in the Cambrian explosion.
300 million years separate cool down and the first fossil prokaryotes.
Reproducing once a year gives 300 million generations. Ideally bacteria
can reproduce in an hour, giving 2.6 trillion generations. Certainly
bacteria and archaea are more complex than they're usually given credit
for outside of microbiology, but I don't have a problem with their
evolution. 300 million years to get working cells, 3 billion years
expanding the diversity of the prokaryotes, 600 million years of
multicellular life... frankly, evolution often seems damn _slow_ to me&.
*Ok, a fair number of people do find it improbable. Lots of people find
lots of things improbably. I don't.
&What the hell were our ancestors doing for the past 100-1000 kiloyears?%
%Probably something, but I'd love to know what.
} are concerns about cosmic rays frying cells in space, but maybe they
} can repair fast, or can hide in rocks.
There was some microbe discovered -- probably an archaean -- that
reportedly could withstand maybe 90 times the normal radiation levels.
I don't know the details, like whether it can be active or if this is in
cyst form (cysts are _tough_). I think the ability was a byproduct of
its mechanisms for withstanding dehydration.
Merry part,
-xx- Damien R. Sullivan X-) <*> http://www.ugcs.caltech.edu/~phoenix
"Undoutedly there is meanness in all the arts which ladies condescend to
employ for captivation..."
Miss Bingley was not so satisfied with this reply as to continue the
subject.
-- Jane Austen, _Pride and Prejudice_, Mr. Darcy
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