On 29/08/2013 04:52 PM, James Holsenback wrote:
> http://www.bbc.co.uk/news/science-environment-23872765

Interesting how they say "Mars had more oxygen", as if that's a basic 
requirement for all living organisms.

There are, in fact, many organisms on Earth to whom oxygen is a deadly 
toxin. Presumably these organisms date from the time when Earth's 
atmosphere was reducing rather than oxidising. It was supposedly the 
spread of photosynthetic organisms to a level where they could affect 
the atmosphere on a global scale which led to the "oxygen catastrophy" 
and the resulting iron oxide deposits that stripe the oldest rocks...

...not sure how all of that fits in with a Mars origin for life. I'm 
also not sure how life supposedly got from Mars to Earth. On a stellar 
scale, our blue planet is a pretty small target to hit.

Also, since water appears to be the fundamental solvent of life, the 
fact that Mars lacks it seems to make it *less* likely as an origin. 
(Although whether talking about Mars or Earth, I think it's safe to 
assume that different regions may have different local conditions. Life 
probably arose in just one specific such region - whichever planet that 
was on...)

Really, if people want to suggest that life travelled here from another 
planet, they're going to need some pretty impressive data to back that up.

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