Science needs the check of experiment and observation because we aren't smart enough to generate very long sequences of inferences from first principles without walking off into fantasy land. For example, check out this exchange between Freeman Dyson and Richard Dawkins. Dyson is a physicist who has made some serious contributions to our body of knowledge. He is a realized genius; the promise of his brilliance was kept. Richard Dawkins on the other hand has made his mark as a popularizer of science. With a second class degree from Oxford, he has admitted difficulties with differential calculus (see A Reason for Everything). Dawkins is a bright enough fellow when measured against the mean, but in terms of g I have no doubt that Dyson stands head and shoulders above him by ~1.5-2 standard deviations. Nevertheless, Dyson says the following:

First response. What I wrote is not a howler and Dawkins is wrong. Species once established evolve very little, and the big steps in evolution mostly occur at speciation events when new species appear with new adaptations. The reason for this is that the rate of evolution of a population is roughly proportional to the inverse square root of the population size. So big steps are most likely when populations are small, giving rise to the ''punctuated equilibrium'' that is seen in the fossil record. The competition is between the new species with a small population adapting fast to new conditions and the old species with a big population adapting slowly.

I don't do the "fisking" thing, and in this case it is too easy. I just want to fix onto his formal allusion; Dyson is basically conflating random genetic drift with evolution itself. He should look up Neutral Theory and its prediction of a constant rate of substitution. And then there is Fisher's Fundamental Theorem of Natural Selection. But even if you reject these models, extrapolate from the assertion he makes to the world around you: do species with the smallest effective populations evolve the fastest???

To think with speed and clarity is critical in modeling the world around us. But to know facts is also important. Freeman Dyson has a excellent inferential mental engine, but he obviously isn't able to derive the insights of evolutionary genetics from first principles on the fly. He should read a book, otherwise he'll have to deal with being schooled by minds of far lesser rate.

Note: Dyson reports that his response to Dawkins' critique was presented verbally at John Brockman's farm in the presence of biologists. That would be George Church & Craig Venter at the least. Perhaps I'm a retard from bizarro world and everything I've learned is turned upside down, but I'm a bit mystified as to why Dyson wasn't immediately corrected. OK, actually I'm not. It seems likely that Dyson was around molecular people would couldn't respond with a sentence as to why the rate of evolution isn't dependent on population size in the way he believes.

Labels: Genetics