Biocurious is a weblog about biology, quantified.

BioStein II

by Andre on 7 April 2005

As promised in his first article, Steven Strauss has published the second part of his essay Why a Lion? He suggests some reasons why the biologists at Queen’s University that he spoke to were so ruffled by his suggestion that biology needs an Einstein and that this character might be able to give reasons why lions exist. As I said in my last post, I think that Strauss addresses an interesting open question in biology: can one write down relatively simple laws that can account quantitatively for – and maybe even predict – some features of life from the perspective of evolution by natural selection.

With that said, I think that Strauss’s suggestion that this theory will answer questions like why there are lions and not centaurs is off the mark. I think that any laws of evolution will have more in common with statistical mechanical laws than with Newton’s laws. As an example, one can easily predict how a block will slide down a frictionless ramp given the slope of the ramp, the force of gravity, and the block’s initial speed by solving the classical equation of motion. On the other hand, one cannot say exactly how each particle in an ideal gas will move over time because of the huge number of particles comprising the gas. The beauty of statistical mechanics is that you don’t need to. You can say very precisely how average properties of the system like pressure and temperature will behave without knowing the precise positions and momenta of all the components of the system: sometimes in nature you can salvage determinism by looking at the collective behaviour of a large number of randomly interacting players.

I think the same would be true for evolution. It may be possible to come up with average properties analogous to pressure and temperature that behave in predictable ways despite the impossibility of predicting when lions will go extinct or centaurs will evolve. It would be a huge discovery for biology.

UPDATE: See here for a hilarious article by Cosma Shalizi and Bill Tozier on models of evolution.



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