The esteemed IQ blog Psychological Comments has a post up comparing Gypsies to Jews. It states:

The contrast with European Jews is instructive: both are minorities with distinctive cultures and world views; both have inbred to some degree; both have been subject to prejudice, ostracism and very much worse; both have struggled to find a niche in Europe, and yet both have (mostly) remained in Europe. However, there the similarities end, and the differences multiply. European Jews venerated scholarship, the Roma cannot see its purpose. Jews made themselves useful at the highest levels of the economy, barely tolerated but sourly respected for their financial and scholarly acumen. Gypsies made themselves resented at the lowest levels of the economy (though some recently became metal recycling millionaires after the fall of Communist heavy industry) and little respected for wheeling and dealing. Here is a thematic apperception test: what made the difference?

Perhaps it was only a difference in root stock: Roma from India, Jews from Italy.

But the original stock of both Roma and Jews are non-white caucasoids. Both groups migrated to Europe where they gradually became more and more white, either because they interbred with Europeans, or because there was actual natural selection for light skin; or both. But “Psychological Comments” seems to be implying that the difference is Jews became white (Italian stock?) while Gypsies remained non-white caucasoids (Indian stock).

But in a groundbreaking investigation, I reported that adjusted for nutrition, the IQ difference between whites (IQ 99) and non-white caucasoids (IQ 90) is only 9 points, yet the difference between Jews (IQ 110) and Gypsies (IQ roughly 70) is 40 points, despite the fact that both live in largely first world countries. How do we explain it?

It should be noted that Gypsies are descended from India’s untouchables (the lowest caste) so they are probably one standard deviation below the non-white caucasoid mean in occupation status. Since IQ and occupational status correlate 0.7, assuming this correlation transcends countries, then we might expect the original gypsies to have IQs 1 SD(0.7) = 0.7 SD (11 points) below the genetic mean of non-white caucasoids (IQ 79 instead of IQ 90). The rest of the low Gypsy IQ can probably be explained by culturally biased IQ tests. It’s known that dropping out of high school causes IQ scores (but probably not intelligence) to drop by 8 points and Gypsies have very little schooling.

In fact it seems that in childhood, a huge sample of Gypsies score 83 on the Raven Colored Progressive Matrices, but another huge sample of adults had IQs of 70 on the same or similar form of the test. Assuming the samples were of the same type of Gypsies, that’s evidence of declining IQ,perhaps caused by dropping out of school. Although I do believe culture reduced IQ tests exist, I’m not sure if the Raven is one of them. I think in order for a test to be culture reduced it has to be fun for all cultures, and the Raven just requires too much thinking and feels too much like school. Indeed scholar J.P. Rushton was struck how many Gypsies independently complained that the test was giving them a headache. I believe dropping out of school makes you intellectually lazy, and this lack of motivation spuriously drags down the scores of the unschooled on tests requiring concentration and persistence.

As for the high IQs of Jews, I think you begin with the fact that the original non-white Jews (genetic IQ 90) interbred with whites (IQ 99) creating a hybrid population (IQ 95), and then only the subset of those of high occupational status were able to maintain their Jewish faith through the generations, which might explain how the average got all the way up to 110. And of course, just as a lack of education spuriously drags down the IQs of Gypsies, it’s possible all the extra days of Hebrew school boosts Jewish IQ, especially since some evidence suggests Jewish IQ increases after puberty (though this could be a genetic effect)