As many of you guys know that the average IQ of american blacks is around 85 and that of sub sahran africans around 70.
What causes this difference? Can people increase their IQ by living in a different enviroment? Or are there other reasons for this difference like:
>Racemixing
>They only took the healthy ones
>They came from regions that were already better than the average
Are there other reasons? Do you have facts that support your argument?
Bonus: Why are black immigrants doing better in the US than the native black population?