Monday, March 13, 2006

The Genetic Geography of Thought 

The New York Times ran an important article by Nicholas Wade Sunday describing recent work in genetics suggesting that recent evolutionary changes can help explain cultural differences.
EAST ASIAN and European cultures have long been very different, Richard E. Nisbett argued in his recent book "The Geography of Thought." East Asians tend to be more interdependent than the individualists of the West, which he attributed to the social constraints and central control handed down as part of the rice-farming techniques Asians have practiced for thousands of years.

A separate explanation for such long-lasting character traits may be emerging from the human genome. Humans have continued to evolve throughout prehistory and perhaps to the present day, according to a new analysis of the genome reported last week by Jonathan Pritchard, a population geneticist at the University of Chicago. So human nature may have evolved as well.

If so, scientists and historians say, a fresh look at history may be in order. Evolutionary changes in the genome could help explain cultural traits that last over many generations as societies adapted to different local pressures.

Trying to explain cultural traits is, of course, a sensitive issue. The descriptions of national character common in the works of 19th-century historians were based on little more than prejudice. Together with unfounded notions of racial superiority they lent support to disastrous policies.

But like phrenology, a wrong idea that held a basic truth (the brain's functions are indeed localized), the concept of national character could turn out to be not entirely baseless, at least when applied to societies shaped by specific evolutionary pressures.

In a study of East Asians, Europeans and Africans, Dr. Pritchard and his colleagues found 700 regions of the genome where genes appear to have been reshaped by natural selection in recent times. In East Asians, the average date of these selection events is 6,600 years ago.

Many of the reshaped genes are involved in taste, smell or digestion, suggesting that East Asians experienced some wrenching change in diet. Since the genetic changes occurred around the time that rice farming took hold, they may mark people's adaptation to a historical event, the beginning of the Neolithic revolution as societies switched from wild to cultivated foods.

Some of the genes are active in the brain and, although their role is not known, may have affected behavior. So perhaps the brain gene changes seen by Dr. Pritchard in East Asians have some connection with the psychological traits described by Dr. Nisbett.

Some geneticists believe the variations they are seeing in the human genome are so recent that they may help explain historical processes. "Since it looks like there has been significant evolutionary change over historical time, we're going to have to rewrite every history book ever written," said Gregory Cochran, a population geneticist at the University of Utah. "The distribution of genes influencing relevant psychological traits must have been different in Rome than it is today," he added. "The past is not just another country but an entirely different kind of people.

Of course, if you are reading Steve Sailer regularly (and you should be), you probably tore through Sunday’s Times searching for the article (he announced it last week). And if you are a really close student of Sailerology, you knew that Greg Cochran would be mentioned in the article. When Sailer says that an important science article is about to be published that is usually code for something having to do with Cochran.

Come to think of it, if you were reading Manhattan Transfer a year ago, you probably are familiar with the subjects discussed in Wade’s article. Back in January of 2005, I wrote about Robert Nisbett’s “Geography of Thought” and speculated that Nisbett was possibly under-estimating the role of genetics in creating the cultural differences he notices. Nisbett pretty much dismisses the notion that genetics could have anything to do with the differences he describes. It seemed to me then that Nisbett’s favored explanation—that agricultural had led to different types of social organization which in turn led to different ways of thinking—didn’t need to exclude possible genetic differences. Given enough time, I would expect that, for instance, rice farming and the resulting cooperative/collective social organization of China would select for those with the genes that made it easier to adapt to such an environment. In the comments to that post, Greg Cochran pointed out that we already had a good candidate for a gene selected in this way.

Of course, the science on this is relatively new. Some still doubt that there has been “enough time” to lead to these changes (although recent discoveries are making this position harder and harder to defend). I suspect that over the next decade or so the science of the genetic geography of thought is going to get a lot of attention, in part because there is still so much left to do in this area. If I were a young population geneticist this is where I would be focusing my attention. If I were a young political scientist, for that matter, I’d enroll in a course in basic genetics. (Actually, it may make sense for someone to start offering a “genetics for social scientists” course somewhere, if they are not already.)

A few years ago, when I first picked up Paul Johnson’s excellent “Art: A New History” I remember thinking how unfortunate it was that he began the first chapter of the opening sentence by writing, “The human personality has been in existence for about 200,000 years, when Homo sapiens first evolved.” Even then I wasn’t sure it made sense to talk about “the human personality” rather than “human personalities geographically distributed” or to claim that anything like a “human personality” had been constant for the past 200,000 years. It reminded me of something you might read from a pre-Darwin British naturalist of the rational-Christian type. In fairness to Johnson, he was thinking about art when he wrote that sentence, not our genetic history. Nonetheless, the time may be coming when even those thinking about art will hesitate before they can assume the psychic unity and constancy of humanity.