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Monday, September 5, 2005

The Grand Unifying Theory

One frequently hears it said that evolution undergirds and unifies all of modern biology which would be devastated were evolution to be somehow disproved. Evolutionary theory, the thinking goes, is the sine qua non of biology.

Such claims, however, have recently come under fire. They're being criticized as at best overblown and at worst completely false. Consider, for instance, this article in The Scientist by Philip Skell, Emeritus Evan Pugh Professor at Pennsylvania State University, and a member of the National Academy of Sciences. Skell writes:

...the modern form of Darwin's theory has been raised to its present high status because it's said to be the cornerstone of modern experimental biology. But is that correct? "While the great majority of biologists would probably agree with Theodosius Dobzhansky's dictum that 'nothing in biology makes sense except in the light of evolution,' most can conduct their work quite happily without particular reference to evolutionary ideas," A.S. Wilkins, editor of the journal BioEssays, wrote in 2000.1 "Evolution would appear to be the indispensable unifying idea and, at the same time, a highly superfluous one."

I would tend to agree. Certainly, my own research with antibiotics during World War II received no guidance from insights provided by Darwinian evolution. Nor did Alexander Fleming's discovery of bacterial inhibition by penicillin. I recently asked more than 70 eminent researchers if they would have done their work differently if they had thought Darwin's theory was wrong. The responses were all the same: No.

I also examined the outstanding biodiscoveries of the past century: the discovery of the double helix; the characterization of the ribosome; the mapping of genomes; research on medications and drug reactions; improvements in food production and sanitation; the development of new surgeries; and others. I even queried biologists working in areas where one would expect the Darwinian paradigm to have most benefited research, such as the emergence of resistance to antibiotics and pesticides. Here, as elsewhere, I found that Darwin's theory had provided no discernible guidance, but was brought in, after the breakthroughs, as an interesting narrative gloss.

Darwinian explanations for such things are often too supple: Natural selection makes humans self- centered and aggressive - except when it makes them altruistic and peaceable. Or natural selection produces virile men who eagerly spread their seed - except when it prefers men who are faithful protectors and providers. When an explanation is so supple that it can explain any behavior, it is difficult to test it experimentally, much less use it as a catalyst for scientific discovery.

Darwinian evolution - whatever its other virtues - does not provide a fruitful heuristic in experimental biology. This becomes especially clear when we compare it with a heuristic framework such as the atomic model, which opens up structural chemistry and leads to advances in the synthesis of a multitude of new molecules of practical benefit. None of this demonstrates that Darwinism is false. It does, however, mean that the claim that it is the cornerstone of modern experimental biology will be met with quiet skepticism from a growing number of scientists in fields where theories actually do serve as cornerstones for tangible breakthroughs.

Some writers have been so carried away in their enthusiasm for the neo-Darwinian synthesis that they've asserted it to be not only central to biology but to all of science. That always seemed to me to be a whopper of an exaggeration. In light of Skell's essay it seems not only hyperbolic but risible.