Thursday, 5 February 2009

What's a half billion years among friends?

This past week, astronomers found the closest extrasolar planet to the size of Earth. It's only twice as big as us, which is significant, because you need something about our size to develop life, and not simply life on an orbital moon. Unfortunately, it's also so close to it's star that its year is only twenty days, and therefore its surface temperature is a balmy 1000°C- so basically a planet of liquid magma. It doesn't matter at that temperature if you've got lots of water; no life is going to develop there.

But I started to think. It wasn't so long ago that our planet was of a similar temperature and composition. Well, 4.5 bya (billion years ago). I suppose that is a stretch of time. And we were able to cool off because there is such a great distance between us and our star; the planet Co­RoT-Exo-7b doesn't have that option. (Yes, extrasolar astronomers have no imagination.) But if it did- if it were further out- it wouldn't be a planet so different than ours, give or take 4 billion years.

We think we are so special, because we have all this life, and advanced life forms to boot. And we are special. Even if life is found elsewhere, it's not everywhere, as our own solar system shows us. But that doesn't give us the right to symbolically lord it over other planets, anymore than we in America can look down at a fledgling democracy in Iraq, forgetting that our government in our first thirteen years collapsed because it was unworkable. Our planet went through great initial turmoil, with some 500 million years of magma and cooling down, before there could even be the beginnings of an inkling for life.
This is why I never think that life itself is all that amazing. Recently, I looked at some stromatolites so close I could reach and touch them. These are fossils of algal mats from 3.5 bya. That means, it took only half a billion years from molten lava to the first life forms. And since life is notoriously difficult to fossilize, life probably began significantly earlier than 3.5 bya- that's just the earliest date we have for fossils. It took another billion years to get anything with a nucleus in it. It took another 1.3 billion years before we could get anything multicellular. It was another 700 million years after that (500 mya) before we got the diversity of multicellular life and phyla that we have today, and then some. If we're looking at the time it takes, the development of life itself is actually the easiest thing in the world. It is getting something multicellular that's difficult, and even more difficult than that, a cell with a nucleus, guiding all the internal workings. The Intelligent Design advocates are barking up the wrong tree. I need no Designer, Intelligent or otherwise, to make life. That's the easy part. It's the development of a nucleus that's difficult. It's the instant creation of a multicellular organism that would be impressive. That is what I must conclude, in that evolution took so long to form them. Complexity is an inherent function of time and natural selection.

No comments:

This is the discussion of the World Science updates as they become available.
Your thoughts are most welcome here.