Re: Mars Fossils

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A point that nobody seems to have made. 
     
Comparative biology is impossible without comparative material. Without a 
suitable model, ultimately based on the extant biota, it is extremely difficult 
to interpret a fossil in a meaningful and testable way. Remember conodonts and 
calcichordates? 
     
Now then, extrapolate this to a putative 'fossil' that does not even come from 
our own planet. There is no a priori reason why extraterrestrial life should 
even be based on terrestrial chemistry, never mind whether it would exhibit 
forms comparable with earthly bacteria -- unless one has good independent 
grounds for believing in panspermia, or that carbon chemistry is essential for 
life (or by moving the goalposts so that life by definition must be carbon 
based). 
     
Even if some extraterrestrial phenomenon appeared to be related to the presence 
of life, it need not be. It could simply be 'inorganic', but how would one be 
able to tell? Wherefore martian pyritic dendrites?
     
I suspect that it will be formally impossible to identify alien life-forms as 
such unless they step right up and demand to be taken to one's leader. And even 
then, there is no reason to believe that such a life-form is not an automaton or
similar.
     
It's life, Norm, but not as we know it.
     
Henry
     
______________________________ Reply Separator _________________________________
Subject: Mars Fossils
Author:  N.MacLeod@nhm.ac.uk at Internet 
Date:    18/08/96 04:08
     
     
     The "discovery" of alleged fossils from Mars ...