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If I may, an alternative theory.

Chinese countryside after 1949 was a collectivized hell (similar to that in the Soviet Union after collectivization in 1930). Life in the kolhoz (or its Chinese equivalent) is quite similar to serfdom (Soviet peasants had their passports confiscated until 1960s, officially 'for safekeeping). Peasants were the most exploited part of the population, facing the hardest consequences (the great chinese famine, Holodomor, soviet famines of 1921, 1946-47, just to name some of those).

Therefore, it was the best interest of any Chinese (and Soviet) peasant to leave the countryside for the city. Or, if not possible, at least ensure that the children move to the city after finishing school. This would result in massive self-selection, and correlation with IQ is quite possible.

In the "West", the situation is the opposite - the "best" can stay in the countryside (let's say, the most capable son staying in the family farm), while the outcasts, adventurers and "surplus population" leave for the city. In this situation, correlation with IQ is less likely.

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That is certainly a possibility. But the fact that the urban population increased from 10% of the population in 1949 to over 30% today means that a significant portion of the rural population migrated to cities. It is of course possible that the cognitively most gifted fifth of the rural population packed up and moved to the city. But it is an awfully large number of people to have been selected purely for cognitive reasons. Still, it seems likely that it is at least part of the explanation.

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founding
May 26, 2023·edited May 26, 2023

My family comes from Mainland China. I may have some n=1 insights here.

I can imagine 3 ways in which selection effects would explain what we see:

1) Self-selection: Imagine for a moment, per your wife's observations on population density driving the development of the human animal, that only those with the greatest levels of executive function (conscientiousness, ability to delay gratification, ability to inhibit violent tendencies, etc., etc.) can thrive in densely populated areas like cities. And, well, certainly cognitive ability would be highly correlated with executive function in general, no?

2) Systemic-selection: The Houko System, like any man-made system, is one designed to favor the shrewdest and the most politically connected. Only those who had high enough cognitive abilities would be able to "play the game" correctly to get a "passport" to the city, to escape the poverty and horrors of the countryside.

3) Selection in the cities: Those who don't have the work ethic and the executive function and the cognitive abilities to thrive in the highly competitive cities end up going back to the countryside.

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> publish first, think later, great strategy for a successful blog!

Most people are too disorganized and tolerant of sloppiness for this to work, but for you, definitely. Readers don't (always) need a definitive conclusion; they want to get to know you, see your evolving thought processes, and be exposed to stimulating ideas.

> If cities are population sinks which are dependent on a constant influx of people

> and genetic material from the surrounding countryside it is very difficult to talk

> about a specifically urban evolutionary history.

Well, only if 1. there's zero gross migration out of the city, and 2. urban graveyard effects don't exist elsewhere. Even though net migration may all be inward, some individuals can make their way outward to influence the source population.

> Studies of the urban graveyard effect in China are, perhaps not surprisingly, thin on the ground.

Too bad - but there *is* a general sociological principle that subsistence style impacts fertility. Foragers have lower fertility rates, then pastoralists and horticulturalists, and then agriculturalists have the highest rates because of the way children provide an excellent pool for low-skill labor which is at a premium for sedentary farmers. Moving forward, birth rates decline in part because the cost/benefit ratio tilts away from large families, and we see this in the ongoing demographic transition today. Essentially, urbanites are further along the demographic transition than rural farmers, so even without data, it seems pretty safe to assume that the urban graveyard effect wasn't merely isolated to Britain.

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There also problem that Mandarin class of scholar-officials is not truly urban people, Mandarin is landlords with rural income and estate.

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author

Thank you for pointing that out. Once again I bump into the very real limits to knowledge of Chinese history.

I have had the impression that the scholarly class in Chinese society was a sort of "pseudo-urban" upper class. Somewhat like late Roman aristocracy who spent most of their time at their rural villas but always kept close contact with the political life in the city. But, as with so many other things Chinese, I might be wrong there.

For the argument in this article the most important thing is really what kind of genetic exchange happened between the scholarly class and the mass of peasantry. If there was no genetic exchange the scholars could have diverged quite significantly from the majority. If there was then a major disruption in landowning, for example due to forced collectivization, then all these landowning scholars might have ended up in the city. But, of course, I am just speculating right now.

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There is one thing I don't get here: Why not assume that the Chinese countryside experienced a great brain drain in the 20th century? If so many people successfully moved into the cities after 1949, couldn't those migrants have been more intelligent than the average countryside person?

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That is very much possible, although not a certainty. If we look at the only thing I know anything about, namely Europe, it was primarily the landless who migrated from country to city during urbanization, not necessarily the cognitively most gifted part of the countryside population. But China might have been entirely different. Being in the midst of a communist revolution which included massive farm collectivizations might have induced all the bright people to flock to the cities. To be frank, I do not have a clue.

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author

If nothing else, we could look at clues from Europe and America. This article about a study in America says that higher IQ people tend to move. Wherever they are, they move somewhere else.

https://qz.com/230249/those-with-the-highest-iqs-grow-up-in-the-country-and-move-to-the-city

The Chinese revolution made everybody landless, so the countryside suddenly became equally miserable for everyone. The incentives to get away from there should have been very significant. If high IQ people are better at getting away from where they are, in post-1949 China they should have moved from countryside to cities.

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I can confirm from long n = 1 personal experience that this is the case. Until I came here, where I've lived for the last five years, I moved an average of once every 2 or 3 years. Moving is a hassle, yes - but it's far easier to move to greener pastures than to convince the grass to grow back after the local industries dumped so much waste into the ground that tap water starts to glow in the dark.

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