I’m thrilled that you’re reading the book but perplexed by your post. As I write on page 213, after discussing the Khazarian thesis: “There is absolutely no credible evidence supporting the popular belief that Khazarians converted en masse to Judaism.” I couldn’t be more direct than that.

What I do say is that there is credible evidence for a conversion of a segment of Khazar’s, probably the nobility. It shows up in the Levite lineage. One possible explanation is that the nobility bought their way into Levite status during a conversion. That’s what Karl Skorecki tends to believe. I happen to be R1a, a Levite Khazarian line.

Jon Entine

I heard your talk at AEI and am reading your book, but frankly you make too much of the Kazars and their supposed “mass conversion.” People rarely converted en masse. It was usually the rulers who converted and the rest of the people remained largely immune to the new religion. Even in Russia, long after the rulers converted to Christianity, the bulk of the people practiced various forms of paganism.

More latter as I read on.

Yale Richmond

I’m actually flabbergasted that anyone would suggest that the hundreds of studies that show, definitively, the huge genetic component of IQ, are unscientific or racist. What planet do you live on? Studies of identical twins reared apart show without question that nature plays the smallest role in shaping IQ. The link between IQ and performance–not just in school/universities but in life, is incredibly strong. The US military has long used IQ tests as a essential basis for accepting or rejecting recruits–and assigning people to different career paths. They’ve found huge correlations between IQ tests and performance.

Let me state this clearly: You would be hard pressed to find a top flight psychometrician who rejects the clear link between genetics and IQ.

As for the issue of Ashkenazi Jewish IQ, that too is unquestioned. Ashkenazi Jews score higher on IQ tests…as much as a standard deviation higher than average–an astounding figure. This is a fact.

Are there cultural reasons for it? Well, there are no quality empirical studies that I’ve been able to find that persuasively show that culture/environment alone can significantly raise IQ scores, despite the dissimulation that usually accompanies discussions of this issue.

Culture does play a huge role in shaping gene evolution however. The spread of the lactose tolerance mutation has occurred in cultures in which people drink milk and consume cheeses. There are African tribal communities, side by side, one that’s lactose tolerant and one that’s lactose intolerant. The difference? The lactose tolerant ones, such as the Masai, have long had a tradition of goat herding and consuming dairy products. That contributed to better health and allowed the mutation to become fixed in that community.

The genes that impact any other behavior or characteristic, including what we call “intelligence,” would be subject to similar evolutionary pressures. Ashkenazi Jews have had a consistent culture linked to book learning since at least the end of the first millennium (Sephardic Jewry had it, but that tradition collapsed during the extended period of the persecution of Jews in Iberia after the “Ornament of History” period in early medieval Spain). Sons and daughters of rabbis and money lenders were married to the ‘best and the brightest’ and had more children than the less successful Jews. That’s how the genes spread.

There may very well be another genetic component as well: Three American scientists — none of whom is Jewish — has proposed a testable theory that certain genetic diseases arose in Ashkenazi Jews because the same genes are responsible at least in part for intelligence. The study says that as many as 19 disorders, divided into two categories—spingolipid disorders such as Tay-Sachs and Gaucher, and DNA repair disorders such as breast cancer and Bloom syndrome –provide the benefit of increased intelligence, despite their negative effects. They promote the growth and interconnection of brain cells. These disease mutations were not passed out of the human genome because their negative effects were counterbalanced by “positive selection.”

Is this theory correct? We don’t know for certain. But it is parsimonious based on the known facts–far more so than the ‘it’s all culture’ explanation, which is farcical. It’s a testable thesis, though it’s not on the front burner considering the far more important issues that could be tested.

I will tell you this: in researching “Abraham’s Children,” I could NOT FIND ONE geneticist who dismissed this theory out right–not in candid conversation. Almost none would put their name to that, however (though a few have done so and are quoted in my book).

However you think about this thesis — and it’s not mine, but a team led by Henry Harpending, a University of Utah geneticist — it’s a serious one and worthy of scientific scrutiny.

Facts like these may pose a problem for many people whose desire it is to believe that equal capacities and abilities are a universal heritage of humanity. That may well be so…but simply wanting that to be the case is not enough. That is not science.

Jon Entine