I love all the stories about the search for water and possibly life on Mars and the new discoveries of more earth-like extrasolar planets, but I just think there's a bit of a perspective problem when it comes to presuming that being closer to earth-like is better when it comes to the search for life. Yes, the only known sample point we have of life is that existing on our own planet (for now), but that doesn't mean that our planet is optimal for the formation or survival of life.

Let's just put this in persepective, as far as we know today it took close to three billion years for life to reach the multi-cellular stage (regardless of whether you're in the panspermia or abiogenesis camp), and today, after four billion years, only 0.00000000126% of the planet has been converted to biomass.

That's a real long time and not much progress to show for it. We may not be living on a fertile world, an optimal environment for life; maybe we live on the galactic equivalent of a barren weed strewn city lot.

Heh, quite a good point. We have the potential to create a utopian and edenistic earth... but most people aren't concerned about it, don't know how, or haven't even thought about it.

We can desalinate landscape and put in forests structured for human use, but we don't:
http://www.youtube.com/watch?v=sohI6vnWZmk

One day ;)

Posted by dylan on 2008-06-28

Maybe, yes. Maybe.

Posted by Aristotle Pagaltzis on 2008-06-28

Hmm. Given that so far our explorations deeper into the earth keep revealing more extremophile bacteria, the estimate may be a bit low. There is evidence, for example, that many ore concentrations (like some iron ores) may be biological in origin. At the very least, this suggests that quite a bit of the earth's crust at least passes through the planetary ecosystem on a regular basis (just like the atmosphere and ocean do) on long time scales, and is far from inert.

Posted by Michael R. Bernstein on 2008-06-29