Sidestepping political correctness, Henry Harpending says intelligence may be genetically predetermined by cultural background. The Thomas Chair Distinguished Professor of Anthropology at the University of Utah, he and two colleagues say they believe central and northern European Ashkenazi Jews until the 17th century may have been naturally selected for enhanced intellect. Their hypothesis was published in the November 2005 issue of the Journal of Biosocial Science.

Though admitting more research needs to be done to substantiate their argument, Harpending explained the premise of their theory to Science & Theology News' Frederica Saylor.

Q: Will you give an overview of your theory on the influence of Ashkenazic genes on intelligence?

A: With a couple of colleagues, we started chatting a few years ago about the biology of Northern European Jews. They're one of the more interesting populations in the world from the viewpoint of human biology for two reasons. First is their high intelligence, and the second is the high prevalence of inherited disorders in the population.

I think Greg Cochran, the lead author of the paper, threw out the idea one day that the two might be related, and we started looking into that hypothesis. The more we looked, the better the idea seemed. We found that several of the disorders were intelligence boosters, so when we'd done about as much as we could just doing mathematics and going to the library, we published this paper saying, "Here's a good-looking hypothesis, somebody ought to test it." There's a lot of substance in the paper, and everything we found supported that hypothesis, but it's still a hypothesis.

Q: Can you outline this hypothesis a little more specifically?

A: If you look at the history of Northern European Jews, they first show up around the year 800. They are traders and financiers " almost all of them are in these professions of trade and finance. They were, for whatever reason, pushed into these occupations that require a high IQ, and they were confined to these occupations for about 800 to 900 years. It's well known from the history that those who did better " the wealthier ones " had a lot more children. So it looks like a situation where there's strong selection for IQ.

Q: What does this mean in terms of natural selection?

A: We know from studies of domestic animals and studies in the laboratory that when you have a strong natural selection of the population, strong selection for something new, what selection often picks up first is advantageous heterozygotes.

We thought an interesting hypothesis was that these Ashkenazi Jewish diseases were advantageous in heterozygotes and in particular that they boosted intelligence. We know that seems to have been the strong selective force under history. We know that whatever favors these Ashkenazi mutations must have been social. It wasn't a disease because it never happened to the people who lived literally across the street from them: the Lithuanians, Poles. It only happened to the Ashkenazi.

Q: Why do you suggest this link may be found only in the Ashkenazi Jews and not in the Sephardic Jews?

A: Northern European Jews were surrounded by zealous Christian politics, where there were two things that a male could do that were approved: He could be a warrior and kill people, or he could be celibate. Nobody wanted these jobs, and management, finance, trade were kind of sneered at among the Christian aristocracy. The Sephardic, they were in Islamic regions where they had a lot of competition: Armenians, Greeks, Arabs who were quite happy to take high-intelligence jobs. The Sephardic had competition and the Ashkenazi really didn't. There wasn't anyone else trying to get into finance, at least in Eastern Europe.

Q: What do you think is true today in Ashkenazi genes?

A: Today, two things are going on, at least in North America. One is Ashkenazi Jews aren't having very many children, and two, there's a lot of marriage with non-Jews. So, I doubt that this process is going on today.

Q: Are there any ramifications today based on your hypothesis?

A: I think there are none, except they continue to have this high intelligence.

Q: What kind of data do you think needs to be selected for further research?

A: If we're right, then in a family where some siblings are carriers, say of Tay-Sachs, and some aren't, the prediction is that the Tay-Sachs carriers would have higher SAT scores than their brothers and sisters. If carriers do seem to have an increased IQ, it's worth looking further into our theory. If they don't, then we're wrong, and we try something else.

Q: Have you encountered roadblocks in terms of people arguing on the other side of your hypothesis?

A: I've had lots of nice, interesting commentary and comments from people. We've had delightful, helpful correspondence with lots of different people.

Northern European Jews have kind of an origin myth that the reason they're smart is that the prettiest girls always wanted to marry the best scholars, so that smart boys got the prettiest girls. There's been a lot of cordial, usable discussion about that with people. It's not politically correct these days to talk about one group being smarter than another. We thought we'd get a lot of hostile reaction, and we haven't had a trace of it.

Q: Do you think religion is something to consider when looking at evolutionary patterns?

A: Religion certainly affects behavior, affects human society, and human society is the context for human evolution. The one thing we point out in this paper is that people make history, but history makes people, and religion is part of history. I don't think you can study human biology without considering religion, but I don't think we have any very good evolutionary theory of religion.

Q: What are your specific research interests?

A: My interest has always been human evolution, specifically human social evolution and human population genetics. I've done a lot of fieldwork in southern Africa with several different tribes there. And I've written a lot about human genetics, modern human origins and human social evolution.