Johnicholas makes an excellent point about the fuzziness of both intelligence and race. The complexities involved with defining both of these concepts has prevented (to my knowledge) anything like a scientific study of the OP's assertion.

Does it make sense to assign a higher credibility to a question of fact on the basis of the opinion of a top expert in the field, when there is no way that his opinion is informed by anything resembling a scientific study? I don't think so.