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Saturday, April 4, 2009

Maybe we aren't so special after all

Listening to the Origins Symposium, I was struck by a statement made by a member of the panel: "Is Our Universe Unique, and how can we find out". Someone suggested that "we have no idea" what to expect of the term of the Drake equation regarding the likelihood of forming intelligent life given the formation of life. I have to disagree. We don't have a precise estimate, but Dawkins and others have suggested a process giving a good enough idea for cosmological purposes.

There is no shortage of politically correct intellectuals who point out that there is nothing fundamentally more fit in evolutionary terms about complexity and intelligence, and intelligence is not inevitable. Why, then? Chance? We could invoke the anthropic principle and call it a fluke, but we have a better answer. Consider a simpler stage nucleic-acid based life as we know it. In the absence of selection, we expect genetic drift, and there are only two directions to move on the complexity scale: up or down. Note that there is a lower bound of complexity below which, it is no longer alive. When governed by genetic drift alone, we expect the distribution of populations to diffuse along the complexity scale. When a useful solution emerges [by chance/diffusion], as with eukaryotes, it creates a new soft lower bound for the complexity of those organisms. Below this lower bound, this new life fails.

So, we have a diffusion process together with a ratcheting mechanism that makes an increasing maximum complexity inevitable, even against selective forces that generally push in the opposite direction.

Further, once we recognize this process, it is not such a great leap to consider that more complex organisms could [and sometimes do] displace and destroy simpler ones. This supports the possibility that the lower bound on complexity for life as we know it could be a soft lower bound that emerged after earlier, simpler life forms. These simpler life forms may have been displaced, destroyed, or hidden by the more complex life.

Given our environment, maybe life is inevitable, and maybe even intelligence is inevitable. Maybe we aren't so special after all.

Anthropic Acid in the Middle of the Cosmic Pyramid

When posing the questions of why/how we exist in a scientific context, the questions can be posed/organized/framed in many ways, but they typically have the same layout. The cosmos can be described as a series of scales and explanatory mechanisms roughly corresponding to the layout of the Drake equation. The possibility of life is can be seen as the product of a series of possibilities:
          Cosmological Possibility
          Universal Possibility
          Galactic/Planetary Possibility
          Chemical Possibility
          Biological Possibility
          Historical Possibility

This weekend's Origins Symposium at ASU is laid out in this way, with cosmologists speaking at the beginning leading to biologists and ending with discussions of human culture. This also corresponds roughly to Dennett's "grades of possibility" as well as the typical ladder of reductionism (philosophy -> physics -> chemistry -> biology -> social science -> philosophy -> just kidding).

Associated with different layers are different formulations of the anthropic principle. When listening to what I would usually consider one of the less interesting and more mundane layers [the formation of earth-like planets -- just a bunch of dirt flying around], I found one of the more interesting formulations of the anthropic principle. It is turning out that earth-like planets may be extremely rare.

If earth is unlikely, then why do we exist? Because we are here to ask that question, of course! DON'T assume, as cosmologists have historically done, that our region of reality/space is typical [the mediocrity principle]! We can only assume, at best, that it is typical of places like ours! It sounds a little circular, but we now have evidence of some formulations of the anthropic principle against the mediocrity principle. I haven't read the article yet, but the cover of this month's SciAm reads "DARK ENERGY Does it really exist? Or does Earth occupy a very unusual place in the universe?"

I suspect that evidence in one layer will spread the anthropic principle through the cosmological pyramid, weakening the mediocrity principle of other layers as well [In case you can't tell, I've been reading Darwin's Dangerous Idea]. Maybe we are special after all.