Israel, India, China and IQ
It has always been a puzzle that Israelis tend to score BELOW the Western average on IQ. Israel is such a brilliant nation scientifically and technologically, that the finding almost seems to invalidate IQ tests. India presents a similar puzzle. Indians do very well wherever they migrate but on average seem to have low IQs back home in India.
As is common, however, the problem would seem to arise from generalizations that are too sweeping and fail to look closely at the populations concerned. I will say a bit more about India below but what needs to be noted is that both nations are NOT ethnically homogeneous. High caste Indians are a lot different from "Dalits" and Israeli "Ashkenazim" (Jews of Northern European recent origin) are VERY different from Israelis of Middle Eastern origins.
And MOST Israelis are of Middle Eastern origins. They are mostly the Jews that were kicked out from Muslim lands after the foundation of modern Israel. Hitler got most of Europe's Ashkenazim West of Moscow, leaving NYC as the great remaining Askenazi centre, and NYC is too comfortable for many Jews to leave.
And at least since the story of Ruth, Jews have never been very endogamous, and Yiddisher Mommas grieve over that to this day. One way or another, Jews have tended to become genetically assimilated into the population within which they live. So many Lithuanian Jews look just like Lithuanians and many Middle Eastern Jews look just like Arabs. Sadly, however, it is not only Arab looks that many Israelis share but also Arab IQ, which is low.
So yes. The Sephardim and Mizrachim of Israel are a bit dumb (though it is VERY incorrect to say so), but the Ashkenazim are very bright and it is they who make Israel an intellectual powerhouse.
Although there are similarities, India is not quite the same. The Northern and Southern Indians do appear to be at least partly of different racial origins and the Northerners seems to be descended in part from lighter-skinned conquerors from somewhere North of India. The conquerors were probably relatively few in number, however, as all Indians are pretty brown.
Indians generally are pretty keen endogamists, however, so the Brahmins are relatively fair of skin and are probably the most closely related to the original Northern invaders. And it is of course the Brahmins who run India. So it is the IQ of the Brahmins and other high castes that is crucial and I know of no studies that have separated out Indian IQ by caste.
And even in India some exogamy does happen. In India, you can generally tell how rich a man is not by his skin colour but by the skin colour of his wife. A rich brown Indian will generally have a fairer-skinned wife. So over the centuries capable Indians from all castes will have worked their way up the status tree and contributed higher IQs to the upper ranges of that tree.
But there is clearly a second influence at work in India: The rural effect. For various reasons a rural background tends to go with a lower IQ. You see that even in South Africa. The Afrikaners (whites of Dutch origin) have a lower average IQ than whites of British origin, even though there is no difference between the parent populations in Europe. And the Afrikaners have always been predominantly farmers.
So the current average IQ of the Indian population is undoubtedly held down by its overwhelmingly rural character. And when even Indians of a relatively low caste move elsewhere, that disadvantage seems to be lost and they prosper -- as in Fiji or South Africa, for instance.
A canny critic might at this point say: "But what about China"? The Chinese are mostly rural and their average IQ is high. Again, however, the very word "China" is an oversimplification. There are many distinct nations within China with their own languages and traditions and a generally low opinion of other such linguistic groups. The picture-based written language of China is not so much an anachronism as a necessity. It's the only way many Chinese can communicate with one another.
And from what I can gather most of the IQ testing has been done on Chinese from the coastal cities. Deep inland in rural China the IQ picture will probably be much different.