Geneticists and psychometricians are generally just as leftist as any other scientists, or at least start off that way.
So for at least six decades fame, fortune and acclaim has awaited the psychometrician who develops a method of testing that demonstrates no difference in intelligence between blacks and whites in America. You can bet your bottom dollar extensive attempts have been made to do so.
That every test they come up with just demonstrates the same old one standard deviation, or about 15 IQ points, difference is IMO the greatest possible proof that it exists. Even those trying to demonstrate that it doesn’t exist keep proving it does.
So ever since then I've been skeptical about the "expert's" view of racial differences. I knew there were real differences physically, then why not mentally? The world won't come to an end if the truth becomes known. Just many leftist's and assorted race-hustler's coveted careers will come to an end.
Likewise, measuring the ability to jump, sprint, sing, dance, eat watermelon, there is more variability(difference) amongst blacks and amongst whites than between whites and blacks.
To put that another way: There is more intra-genepool variability than inter-genepool variability
This applies to many other things. There is more variability in the quality of the trucks in Mexico and more variability in the quality of trucks in the US than there is variability between Mexican trucks and US trucks.
The dog-whistle being "in America".
I'm certain that blacks in other civilized countries around the world don't have this IQ problem.
Of course, the second a brilliant African doctor moves to the US, his IQ numbers are flushed down the dumper by the demographic "African-American" culture's average.