My information comes from first hand experience in Cameroon, Ivory Coast, Togo, Senegal, Chad, Nigeria and Egypt. I found this abstract only now. This chart corroborates what I have witnessed first-hand.
I believe culture affects IQ.
I don't know why anyone would even argue it doesn't.
The acrimony always comes up when folks debate what comprises and forms particular culture.
I think geographic isolation has always been a big factor.
Anyhow....you've pushed the big button here and many new age Conservatives prefer to ignore that area of realism.
I've spent a lot of time in Africa too....a whole lot in Sierra Leone in the 80s.
I do not believe one can bring entire cultures through massive change from near bronze age to our era in an historical overnight. Of course, it can be done with individuals and it helps if good leaders are found....something Lower Africa has never had.
I'm noting with interest the difference between Hong Kong (107) Taiwan(104) and the rest of China (100). I wonder how much of it is explained by generations of the brightest Chinese going to Hong Kong to seek their fortune in the capitalist oasis of China, as well as the Chinese middle-class fleeing communism to Taiwan?
Go Italy, it's right up there.