some quick questions on exobiology

Mark Siddall mes at
Sun Jul 24 14:54:25 EST 1994

>In article <1994Jul20.220444.18261 at> story at writes:
>>kand why would one expect life on space stuff?

In article <30uba0$bsp at> frist at () writes:
>I dunno, why?

>In article <1994Jul20.220444.18261 at> story at writes:
>>Finally, a virus as I understand it is not a free living organism. So
>> to postulate space viruses one must presumably postulate "higher" cells
>> as well, out there.

In article <30uba0$bsp at> frist at () writes:
>Correct. Viruses are completely dependent on cell hosts for replication.

Absolutely correct!  In fact, the old debate of "viruses are life! - no
they're not!" is finally seen as silly in this light.  From 
what we can gather, life here has a few basic things in common: 
1) nucleic acid
2) water

Even if we limit it to that, what are the odds of "life" evolving in the
same way "out there"? slim to none I'd say.  The universality of 
nucleic acid in organisms here (infectious and otherwise) is more
evidence of common ancestry and monophyly of life than it is evidence
of it having evolved multiple time here.  
Fears of space viruses and other pathogens are a bit outrageous.  Even
if there were such a thing, it likely wouldn't have a compatible 
"genetic" code, morover, if "it" evolved in a water-free or oxygen-free
environment, it'd likely find life forms on earth rather toxic!


Mark E. Siddall                "I don't mind a parasite...
mes at                    I object to a cut-rate one" 
Virginia Inst. Marine Sci.                     - Rick
Gloucester Point, VA, 23062

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