Thursday, February 19, 2009

An evolving picture

February is the 200th birth anniversary of Charles Darwin and the 150th anniversary of first publication of his On the Origin of Species. Not surprisingly, the monthly theme for The Year of Science is evolution.

Evolution is, pure and simple, one of the most powerful and elegant ideas in science. That said, the last thing the web needs is more yammering on the meaning and power of evolution. So how, you ask, am I going to eke out a post from this topic?

My pre-authorial background is primarily in physics and computer science. Both disciplines rely powerfully -- if in very different ways -- on the power of abstraction. Knowing when it's okay (and when it's not!) to:

  • leave pesky third-order effects out of a simulation
  • apply idealized conditions ("Friction? We don't need no stinkin' friction.")
  • calculate with difference equations (discrete-valued) rather than differential equations (continuous-valued)
is a key to success in both physics and CS. So: abstraction, approximation, simplification ... but how far can one carry it? Mae West to the contrary, too much of a good thing isn't always wonderful.

Albert Einstein once (apocryphally?) said: A theory should be as simple as possible, and no simpler. A good scientist has the insight to find the right degree of abstraction to make progress on the problem at hand.

Given my background, what most fascinates me about the discovery of evolution by Darwin (and, to be fair and complete, also by Alfred Russel Wallace) is the attendant use of abstraction. Think, for a moment, about random variation, aka genetic drift, and natural selection. Both are extremely powerful notions -- and no one 150 years ago had a clue what physical mechanism(s) might underlie either. Mendelian genetics, its significance unrecognized until the early twentieth century, began to give a clue about how evolution might work -- again, without any notion what the underlying mechanism(s) might be. Crick and Watson did not publish their seminal paper on DNA and its role in cellular biology until 1953. Not so much as an entire bacterial genome had been sequenced until 1995.

My point? How easy would it have been to abandon evolutionary theory in its early stages for lack of complementary theories/discoveries to explain evolution's deeper levels? Knowing how and when to abstract is a wonderful thing -- rarely so well and insightfully done as during the early stages of developing evolutionary theory.

So: Happy 200th, Mr. Darwin. And while I'm at it, thanks for the idea behind -- even the title of -- Fools' Experiments.

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