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Thursday, July 25, 2013

We are still evolving

I was having a discussion with a friend recently about the influence of genetics on mental gifts. I was saying that my grandmother used to track various talents through the family. So and so got the music, someone else got the math, and so on.

To my surprise, my friend said that genetics played no part in mental gifts, that there was no such thing as music or math gene. I tried to make it clear that I wasn't saying there was a single gene for either of these, but there were clusters of genetic predispositions that quickened interest and skills, and even attitudes. He maintained that it was all due to early experience and environment.

On reflection, it does still seem to me that such gifts run in families, and although environment surely plays a part, it doesn't seem like much of a stretch to say that genetics does, too. If genetics can affect a pancreas or heart, why couldn't it also influence a brain?

It interested me, so I've been doing some reading. Today I finished "the 10,000 Year Explosion: how civilization accelerated human evolution," by Gregory Cochran and Henry Harpending. The thesis was one I hadn't seen before. We know that about 40,000 years ago, there was a burst of creative energy, the sudden appearance of cave art, tool-making, apparent funeral rites, and so on. According to the authors, this was the beginning of a spurt of evolutionary change that continues.

Among the things they cite is the architecture of alleles, which reveal how recently changes have happened. Skin and eye color variations have all happened within the past 10,000 years! (Before then, people were dark-skinned and brown eyed.) Other changes, like the adoption of lactase tolerance, are even more recent. In the second to last chapter, the authors detail how the Ashkenazi Jews, through genetic isolation and selection from roughly 800 AD to 1700 AD , wound up averaging just a little smarter than the rest of the world, with significant results in the world of scientific achievement, among other things.

The book details many stories of how genetic traits appear, and how rapidly they spread, or die out. The whole thing was new to me. Like most folks, I thought that humans have been about the same since we killed off the Neanderthals.

Something that stays with me is the story of how someone tried to domestic a fox. By just choosing the tamest of the litter, and breeding them together, he wound up with a tame fox in just a few generations. The surprising piece was that the physical appearance and other behaviors changed, too. The head got rounder. The ears got floppier. They exhibited, into adulthood, behavior that was more like fox pops. It's a recapitulation of the domestication of dogs.

If changing our diet (adopting dairy farming, or moving to grains rather than nuts and berries) can quickly affect changes in our physiology, imagine now what exposure to technology may be doing.

The point: human evolution isn't over yet. It may be picking up speed.


Lynne said...

This is very fascinating! I'm going to read this book!

Jamie said...

Thanks, Lynne. It's a quick read, but I love running across new ideas.