Re: Meteorite Yields Evidence of Primitive Life on Early Mars

[Nick Longrich <longrich@phoenix.Princeton.EDU>]

        If life actually has existed/ does exist (in which case, it would 
presumably be deep underground, since that's probably where any liquid water 
still remains) it will naturally shake up everything to discover that 
life has evolved independently of life on earth, and then, there's the 
possibility that it will shake up everything because it's related to life 
on earth. If transport (meteors, of course, being the main vector) were 
possible, then Martian and Earth life might be relatives. Life would have 
to be somehow living on/in stone blasted into orbit by a bolide impact, 
travel the millins of miles to another planet, and then impact in a 
habitable area, all without being cooked too thoroughly by takeoff or 
reentry, sterilized by solar radiation, or frozen to death by the cold 
background temperatures in space. This, of course, would make floating to 
the Galapagos from South America on rafts of vegetation look like a fun 
way to spend the weekend, in comparison. 
The odds are astronomical, surely, but there 
were probably an astronomical number of meteorites 3-4 billion years ago, 
as well, and it might only take one seeding to establish life on another 
planet.
        So it might be possible that Martian life is actually a 
descendant of earth life. The reverse is also possible- consider, for 
example, that Mars might have cooled to habitable temperatures before 
earth, due to its relative lack of radioactive elements like uranium, its 
smaller size, and its greater distance from the sun (which could mean less 
heat and less UV than the earth, which lacked an ozone layer until 
oxygen was present in large quantities). So the mailing-list tie-in would 
be the MCF hypothesis (Martians Came First), meaning that Archaeopteryx, 
Giganotosaurus, Edmontonia and all the rest (not to mention insects, 
lemmings, Pee-Wee Herman and everything else) could actually be 
descendants of "extraterrestrials" and "Martians".  
        This sounds out there, but I think it is scientific, in 
principle, at least; it's testable, although in practice, it would be 
very expensive. It just needs answers to a few questions: a) is it 
theoretically possible for bacterial spores or organisms of some kind to 
survive the heating, cooling, and radiation experienced during a 
meteorite's journey between Earth and Mars (given the amount of stuff 
flying around the solar syem in the early days, it's probably a given 
that meteorites went between planets relatively often)  b) does life 
exist on Mars/ Has life in the past existed on Mars ? c) 
if life does/has existed, how does it compare with Earth's life (similar 
proteins, does/ did it use DNA, if so, are there any similar genetic 
sequences?) d) assuming one does find any similarity, which way did the 
transfer take place? ( I don't know how you'd answer this one with 
anything but circumstantial evidence). 
        And of all these, a) is the most practical to answer, since you could 
probably simulate it in a lab. Has anybody actually written any papers on 
that?
        Not that I think any of this is likely, or even necessarily 
possible, but it could be a question worth answering.