Wednesday, January 23, 2008

The Fish Within Us

That title belongs to a fascinating article in Newsweek by Jeneen Interlandi on some parts of the history and the current state of human genetic evolution. Focusing on the work of Neil Shubin:
But while world headlines marveled at the idea that our own hands were somehow descended from these fish fingers, Shubin began exploring the anatomical vestiges of our previous lives. If we evolved from fish, he reasoned, our body design should look more convoluted than rational. Over the next few years, he found ample evidence to support his claim: our veins meander inefficiently, our knees give out easily under the weight of bodies they were not designed to support and our brains are clumsy upgrades from earlier models.

I suppose that proponents of "intelligent design" must now confront the unintelligent parts of our makeup. (There are earlier discussions of this problem in, for example, The Blind Watchmaker.)

Shifting to the work of Henry Harpending, the article then considers the pace of evolution today:
The findings have turned some traditional assumptions on their heads. For decades, biologists believed that human evolution had ground to a halt about 10,000 years ago, when the dawn of agriculture and technology gave us unprecedented control over our environments and made us masters of our own destiny. But rather than slow evolution down, those advances, Harpending says, enabled humanity to hit the accelerator. With better technology, our ranks have swelled from millions to billions. This has driven us to colonize more and different regions of the globe. More people mean more mutations, and more environments mean more things to adapt to. Migration into the Northern Hemisphere, for example, has favored adaptation to cold weather and less skin pigmentation for better sunlight absorption.


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