I have learned this mostly from my friends in south america. And we now have the genetic data, testing data, and economic data to confirm it. But the problem facing south america is that there are just toooooo many people at the bottom for the people at the top to provide sufficient incentives to the middle class, who in turn will provide sufficient incenties to the lower class, so that it’s possible to productively organize society.
It’s not as bad as islamic countrires, where people are highly illiterate and where Islam teaches people that they can be emotionally expressive and emotionally impulsive. At least south american s are still christian. But it’s just almost impossible to create a window within which the people can be organized, and a sufficient middle class developed, to raise the population out of poverty.