Parallel Evolution

Now more than just a convenient assumption for casting in old sci-fi movies:

In his fourth-floor lab at Harvard University, Michael Desai has created hundreds of identical worlds in order to watch evolution at work. Each of his meticulously controlled environments is home to a separate strain of baker’s yeast. Every 12 hours, Desai’s robot assistants pluck out the fastest-growing yeast in each world — selecting the fittest to live on — and discard the rest. Desai then monitors the strains as they evolve over the course of 500 generations. His experiment, which other scientists say is unprecedented in scale, seeks to gain insight into a question that has long bedeviled biologists: If we could start the world over again, would life evolve the same way?
…
Desai’s yeast cells call this belief into question. According to results published
in Science in June, all of Desai’s yeast varieties arrived at roughly the same evolutionary endpoint (as measured by their ability to grow under specific lab conditions) regardless of which precise genetic path each strain took. It’s as if 100 New York City taxis agreed to take separate highways in a race to the Pacific Ocean, and 50 hours later they all converged at the Santa Monica pier.

One of my favorite Vernor Vinge quotes goes “Evolution doesn’t select for intelligence, it heads blindly for local optima.” In addition to not favoring intelligence, local optima may also not be particularly varied, particularly in a lab setting.

But some things are basic to life. For instance, we know now that non-carbon-based life is very unlikely as proteins have a chemically freakish ability to store information, allowing a spontaneously arising protein string to program incredibly complex factories to replicate itself — and then build an entire multicellular organism to house, protect, and continue replication of that protein, again all by chance. There is almost certainly no other class of compounds in which this is possible; we see complexity in some things like boron compounds but nothing that works anything like DNA.

Eventually I suspect we’ll learn that the universe has some absurd finetuning that happens to produce this chemical ability in our “organic” elements, and that even then the spontaneous arrangement of amino acids in a sequence that creates multicellular life (and particularly intelligent life) is extremely rare, much less than one per visible (or causally connected if you like) universe. The power of the weak anthropic principle is only just beginning to become apparent.