I can only assume you are talking about the widely debunked 'race science' component of biology. Most of that was not only wrong, but explicitly constructed just to provide a scientific sounding excuse for slavery and associated practices, like widely cited 'studies' comapring IQs of black and white children in apartheid South Africa.

This is all not to mention that 'race' is not a biological construct, and virtually none of these studies actually check the genetics of the individual. They simply assume that black skin correlates with a particular genotype, without any reason to believe that thr genes for skin color are in any way correlated with any genes which could predict IQ.

It would make more sense to compare IQ across geographical locations, since geographical separation is a strong predictor of genetic separation as well. However, there you end up with huge confounding factors stemming from culture when trying to measure IQ.