One argument for hereditarianism is that, around the world, mixed-race populations have IQs, or other standardized test scores, that are intermediate between the two races they are a mixture of.
Of course it’s messy, and we’re relying on subjective classification, but subjective classification is usually the same as best-fit genetic cluster anyway, and of course some populations of blacks could be genetically more intelligent than other populations, just as some populations of whites can be more intelligent than other populations of whites, and even some populations of blacks can be more intelligent than some populations of whites.
