Life on Earth arose about as soon as it was possible for life to arise [View all]
Last edited Tue Apr 22, 2014, 01:21 AM - Edit history (2)
The first billion, billion and a half years of Earth was wall-to-wall lava and earthquakes and pretty Dante-esque. We were slammed with huge space debris all the time as our gravity cleaned up all the trash in our path that hadn't already become part of a planet. Something slammed into us so hard it knocked off a piece of Earth the size of the moon (which we today call "the moon"
But pretty much as soon as the Earth cooled and the in-fall of comets and asteroids stopped wrecking everything life popped up. No later than a half-billion years of when it plausibly could have, and probably sooner. (It was all bacteria type stuff at first so the fossil record is more than spotty.)
It might have popped up many times, but the life based on RNA and then DNA got established quite early on and if there were competing life modes... well, they were delicious.
We have some reason to think life is likely. Not certain, but a decent chance of popping up anywhere, given the right conditions. (Maybe Earth, our sample of one, was a super-fluke but there's no reason to assume we are exceptional.)
The right conditions are not the planetary norm, of course. Far from it. But I think that if we had some means of zipping around the universe we would find few lifeless Earth-like planets... with just powerful sunlight and water and rocks and wind. (And of the lifeless Earth-like planets we did find, how many of those would develop life in the future?)
The error in assuming that life is a fantastic long-shot comes from (in addition to people thinking we're special) underestimating the size and power of the chemical calculating engine that a lifeless ocean would be.
Without microbial life to break-up/eat exotic large hydrocarbon molecules that form and combine over time, those exotic molecules don't "die." They just keep on keepin' on, bumping into stuff and sometimes forming even longer, more exotic molecules.
It's like the lottery. Will you win? No fucking way. Forget about it.
Will somebody win? Of course. If not this week then next week... there's millions of people playing the thing.
Life on Earth is merely *somebody* winning the lottery.
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