Natural History

From the Philadelphia Inquirer.

Conventional wisdom holds that if you could bring back someone from 40,000 years ago, he or she would blend perfectly well with today’s population.

After all, the fossils show that our ancestors were “anatomically modern” by 100,000 years ago, and by 40,000 B.C., they were creating complex tools and art.

It was easy to assume our species hadn’t evolved much since then.

Now molecular biology is overturning that assumption.

Evidence for more recent evolution is coming not from fossils but from patterns seen in the DNA of contemporary people. Genes show that blue eyes, for example, apparently didn’t exist until 6,000 years ago, and the ability to digest milk goes back just 7,000 years.

***

Evolution through domestication can happen in just a few centuries, said Washington’s Akey, who also studies genetics of domestic dogs. He’s comparing breeds to see where the DNA is separating the Great Danes from the dachshunds, the border collies from the poodles.

Oddly, he said, he has found a parallel – at the DNA level, dogs and humans are showing some of the same changes. It’s possible, he said, that both dogs and humans needed to acquire new disease-resistance genes in response to crowding. Or it could be a reflection of the taming and domestication of both species.

Dog brains are smaller than those of their ancestors, the wolves, and likewise our brains are apparently smaller than those of our ancestors 20,000 years ago, Harpending said. The human brain hit its peak and then began shrinking.

It may mean our ancestors needed more brainpower to survive in the wild, or it could be that our brains have become better organized and more compact – just as computers have done, he said.

It’s a mystery, but perhaps there’s an answer somewhere in our DNA.

I found the article interesting, but I need to make some clarifications.

Neanderthals had bigger brains because they were physically larger than us.  The same is true for modern humans who lived 20,000 years ago. We are smaller now.

It is true that agriculture has had some unintended consequences. Starvation and malnutrition, along with uncontrolled population growth are major problems with  the advent of agriculture. Another one not often mentioned is the development of extreme inequality between people has its roots in development of agriculture. With hunter-gatherers, meat and work tend to be more evenly distributed, because everyone has to contribute something.  If someone has a beef with someone in a hunter-gatherer economy, the aggrieved party can simply leave. Thus, there was incentive to ensure that everyone got his or her fair share. Within agricultural societies,  some people were able to gain more power others simply because some people wound up controlling the land upon which everyone depending for survival.  People lost their ability to leave if conditions became bad. Thus, a slave owner or lord could work his servants until they nearly died, while a chieftain of a hunter-gatherer band would not allow members of his clan to starve.

I don’t waste time on the comparative intelligence of races or ethnic groups. I’m not the biggest fan of Herrnstein and Murray. (Stephen J. Gould had a far better analysis of this whole issue.)