What you say about blacks never developing a written language makes sense but it does not apply to all of them. We have Clarence Thomas, Condalisa Rice, Walter Williams and others who don't fit that mold. Our nephew and his wife adopted a black boy directly from Africa, they saw him there as an infant and waited 2 years to get him. He is as black as a lump of coal, no white blood, and he is brilliant. At about 10/11 years old he devours books, I am told. People like him should have raised the intelligence level of the tribe, apparently there weren't enough of them.
This black boy lives in Arlington Texas BTW.
People like him should have raised the intelligence level of the tribe, apparently there weren't enough of them. I don't think anyone disputes that the full range of intelligence from very low to genius can be found in all groups. It's the average intelligence of the groups that are consistent around the world based on IQ tests, and the reasons for that is where the controversies lie.