A lot of Intelligent Design proponents believe that cells are too complex to have arisen randomly. They point to the micro-machines of the organelles and say that there is no way this could happen randomly.
This is a total fallacy.
Here’s the trick:
You only need to create ONE reproducing structure for it to multiply. At that point, things are self-sustainable.
Now in a small environment, you’ll quickly exhaust the source of raw materials needed to make new things. Which means that unless you provide more raw materials, that particular strain of life is gone.
There is another solution though – more random changes. Until you end up with something that more effectively uses those resources – or can cannibalize the other entities.
This, in and of itself, pretty solidly ensures the direction of evolution – the pressure to more efficiently cannibalize resources form the environment ensures that complexity will increase in the long term. The only other alternative is the whole system stalls and dies out.
So that first guy happens randomly. Pure chance.
And it has millions of years, and changes on the orders of milliseconds within which to do it (chemistry works fast).
That’s just for the first one. Once you have one, you can have random variations. But the one that works still exists. And it can change any way it likes, as long as it keeps making new ones that reproduce and compete better. Otherwise, again, something else that competes better will win. And that will gain the upper hand instead.
By the way, on the timeline of the Earth, a million years is nothing. If you have one variation per millisecond, that’s about 31,536,000,000,000,000 opportunities for one combination of chemicals to turn into something useful.
Cool it down, and long-range low-entropy effects take hold, allowing some protein machinery to work differently – forming interesting configurations which are necessary for life. (A guy did an experiment a while back with some chemicals in ice (sorry for the pay-only NewScientist link); after 25 years he checked back, and he had amino acids in there. And RNA can replicate without its usual need for enzymes if it’s cold).
But let’s ignore the cooling for now. That 31,536,000,000,000,000 opportunities? That’s in one place. If we allow one of these experiments to happen per square meter on the earth’s surface, the changes we can have over a million years start looking like 6,312,000,000,000,000,000,000,000,000,000,000,000. Or 6×1036.
The universe started – as best as we can tell – about 1.37×1010 years ago. So if you want the number of chances you have for life to randomly happen in its simplest form, it’s more like 8×1040 opportunities. That’s per Earth-like planet. Assuming that Earth-like conditions are required for life (which they probably aren’t).
There are roughly 100,000,000,000,000,000,000,000 (or 1×1023) Earth-like planets in the universe.
So let’s run that experiment again. We now have 8×1063 chances for life to happen. While you were reading this blog post, life had the chance to spontaneously arise approximately 1×1040 times.
The question you should ask yourself is not how unlikely is it that life would arise purely by chance, but rather, why don’t we see it everywhere we look?
Next time… The Pyramids, Skyscrapes & Evolution. I promise you that all these things really do go together – like Peanut Butter & Jelly.