Life forms… precious little life forms… where are you?

Just because there was a discussion on a video game forum recently, I thought I’d reiterate some of my thoughts on here, for prosperity.  And also so that in years to come I can look at it and think ‘jeez… how could I have got it so wrong?  I was so stupid then…’

But, that’s fine really; science is an ongoing process of gathering evidence and experimentation.  Scientists don’t claim to already have all the answers.  If we had all the answers, then science would stop; we’d know everything so there’d be no need for experiments or research or cushy grants… so maybe science really does have all the answers already, but scientists have realized it’s not in their interests to tell us…

Anyway, one thing we don’t yet know the answer to is how life on Earth got started, which we would need to know to have a better idea of the probability of it starting elsewhere.  Obviously research is ongoing and some think they are getting closer to an answer.  But the point really is that life on Earth is currently the only sample we have.

But the good news is that the elements of life as we know it, the stuff we’re made of like hydrogen, oxygen and carbon… these are all very common elements in the universe.  We’re not made out of anything rare or unusual.   There’s also now evidence that life on Earth started quite early in the planet’s history, 3-4 billion years ago, suggesting that maybe it isn’t really that difficult, and possibly wherever the right elements and conditions are met, there’s a good chance life will start.

We also now know that most stars seem to have planets around them.  There are over one hundred billion stars in The Milky Way galaxy… so, let’s say there are one hundred billion planets with the right conditions for life (some stars will have no planets in their habitable zones, and some will have several… also a world doesn’t necessarily have to be in the habitable zone of the star to support life, but that’s a whole other discussion).

Like I mentioned earlier, we don’t know exactly how or how likely it is for life to start even when all the conditions are right.  So let’s say that life only starts on 1% per cent of those worlds… that’s still 1 billion planets with life in our galaxy.

But returning to Earth as our only example, although life started quite early, it didn’t really start to do anything interesting until about 500 million years ago when it started becoming multicellular and all different animal groups started to emerge.  So most life out there is likely to be simple, single celled organisms.  So let’s say just 1% of those billion worlds evolve multicellular life… that’s 10 million planets with things like plants and animals on them.

But now we start getting to the big one; intelligence.  Or at least what we think of as intelligence – the ability to create tools and language and science.

Again, if we look at our planets (as if we’ve any choice right now), we can look at how often certain traits have evolved.  Eyes, for example, evolved quite quickly and lots of different times, so we can reasonably expect whenever life evolves in a place with a light source, it will probably have some kind of eyes.

But then we had giant reptiles and dinosaurs stomping around the planet for a few hundred million years, basically doing nothing but get bigger and fatter and angrier.  I love dinosaurs, but they wasted so much time, and then were all killed by a rock.  The mighty lizards had their chance, and mightily failed.

The trouble is, our own human-like intelligence has only evolved once, in us, just a few hundred thousand years ago.  It’s tempting for us to think of big brains as the ultimate goal of evolution, but of course it doesn’t really work like that; it’s about survival.  The trouble is that big brains have disadvantages as well, like they require a lot of energy… so let’s say that the chances of intelligence are small as well.  Just another 1%… in fact lets say just 0.1% of the planets that have animals on them evolve human-like intelligence.

That’s still 10,000 planets with intelligent life.  If only 1% of those figure out how to make radios and venture into space, that’s still one hundred civilizations we could make contact with just in our galaxy.

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