Sunday, April 27, 2008


A Whiff of Evolution

There is an article by Faye Flam entitled "Story of evolution can be seen as comedy of errors" that is based on Neil Shubin's Your Inner Fish, a book I recently finished and found to be a very readable and clear explanation of the power of evolutionary theory to explain the living world around us. It also makes the case against the concept, not originating with Darwin, that was the real generator of eugenics and worse:

[B]y focusing on our less lofty traits, evolutionary biology can help dispel one of the most egregious and even tragic fallacies surrounding Darwinian evolution — that it moves toward perfection, with man at the apex of some towering ladder.
But it was this part of the article caught my attention:

No good story about human design flaws can pass up a discussion of flatulence — and science has addressed the kind that would occur if everyone in the world drank a tall glass of milk at the same time.

Geneticist Pragna Patel of the University of Southern California said one of her favorite examples of evolution in progress involves the gene that determines who can digest the sugars in milk and who cannot.

From genetic studies it appears that so-called lactose intolerance was our ancestral state.

A few people, however, were genetically gifted with an enzyme called lactase, which breaks down lactose, and in groups that started drinking lots of milk around 10,000 years ago, that version of the gene started to take over.

Scientists recently sequenced the lactase gene and found 43 different variations that allow adults to drink the milk of other animals.

"It's the first clear evidence of convergent evolution," Patel said, though it's not known whether those lacking this innovation failed to pass on their genes because they suffered from lack of nutrition or just didn't get invited to any parties.

Of course, flatulence resulting from drinking the milk of other species is not a design defect ... unless you think that the very intelligence that permits us to domesticate animals is a defect. And, considering that the same intelligence enables us to make things like Expelled, maybe there's a case for that.

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