IQ being one number is like SATs…

It’s an average of a bunch of different subjects, one of which is “crystalized intelligence” which is basically trivia pursuit. You have to miss 3 questions in a row, when I was tested I ran out of questions because I never missed three in a row. It took forever.

Which means that it is linked to e.g. corruption, education, crime?

The root cause is resource scarcity. All those other problems can lead to that.

If you want to look more into that specifically, look into the "marshmallow test’ and how being able to wait for a largest reward is the largest signal of success as an adult. Resource scarcity makes us take the guaranteed small payoff instead of waiting.

Those changes as a child follow us our whole lives. It’s one of a handful of things that’s set for life by the time we’re toddlers along with in group/out group.