They are if you are willing to accept IQ scores as a proxy, the Wikipedia article for »IQ and the Wealth of Nations« [1] has a world map of average IQ scores. T

They are if you are willing to accept IQ scores as a proxy, the Wikipedia article for »IQ and the Wealth of Nations« [1] has a world map of average IQ scores. This whole topic is of course highly controversial because in some sense it is right around the corner of racism. There is substantial debate about the accuracy of the data, the magnitude of the effect, nature vs nurture, appropriateness of measuring IQ, biases in the methodology, the direction of the causal relation and so on. But if you stay away from the details behind the effect and just look at the measured data, you see an unequal distribution of average IQ scores across the globe. The effect may not be as large as the referenced book claims, but the difference has been confirmed by critical responses albeit with reduced magnitude. It is pretty hard if not impossible the get an unbiased picture of this topic, so I will leave it at this and ask you to dive into the rabbit hole yourself, I don't want to accidentally spread false claims because I am certainly no expert on this. [1] https://en.wikipedia.org/wiki/IQ_and_the_Wealth_of_Nations https://en.wikipedia.org/wiki/IQ_and_the_Wealth_of_Nations