QUESTION:
I have recently heard of the possibility of microbial life on Mars. 
It seems a likely possibility, although almost everyone would say 
that intelligent life on Mars is non-existant.  This is because there 
is almost no atmosphere and no liquid water.  However, is it by any 
means possible that there can be subterranean intelligent life forms 
on Mars?  I am asking this because we have only sent a few probes to 
the surface of Mars.  And aliens looking down at earth (for the first 
time and w/o doing a deep scan, LOL) wouldn't be able to tell that
there are limestone caverns underground earth.  Which are habitable for us,
though not comfortably, maybe for an alien though.

ANSWER from Jeff Plescia on October 21, 1999:
There is very little probability of current or past intelligent life 
on Mars.  The reason is that the climate was such that conditions 
were right for origin and simple evolution for only a short period of 
time early in history.  If any life developed it would not have had 
time to become intelligent before the environment changed. At present 
the thought is that perhaps there could be some simple
microbial life below the surface where it is warm and wet.

Intelligent (if you mean human like) life on Earth has been around 
for only perhaps a few million years.