From: jonlennart.beck.god@damn.get2net.that.dk.spam.retro.com   
      
   "Steen Eiler Jørgensen"  skrev i en meddelelse   
   news:40014a3b$0$139$edfadb0f@dread11.news.tele.dk...   
      
   > Should human activity on Mars bio-contaminate the surface, it should be no   
   > problem for a trained biologist to spot the difference between terrestrial   
   > microbes and organisms never encountered before.   
      
      Not necessarily.  If Terran microorganisms are introduced to Mars, and   
   some of them survive and actually grow, they will be subject to an enormous   
   selection pressure.  A few decades might change them beyond easy   
   recognition.  Do microorganisms have enough junk DNA, which is not subject   
   to selection pressure, to establish kinship?   
      Also, there is the possibility that Earthlife has already been introduced   
   to Mars, a very long time ago.  Imagine a large meteorite strike on Earth;   
   some of the ejecta somehow reaches Earth escape without being cooked, and   
   Terran microorganisms survive in hibernation, well protected within the   
   rock.  Then this rock impacts Mars, in such a way that the central parts of   
   the rock is not cooked.  Discovering Mars-life with this particular kinship   
   to Earthlife would be a considerable scientific find.   
      
   Jon Lennart Beck.   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)