That's ridiculous. Let's hypothetically say it is true that there is a intelligence difference. There would be a lot of black people who are over the average in IQ or whatever measurement you prefer who suffer because of it. Have you ever heard variation within groups is greater than variation between groups? There will never be any use to knowing racial group averages. It will always be necessary to evaluate at a individual level. If some idea like this became accepted the consequences would be very ugly. There would almost certainly be race based violence, tension, and discrimination on a large scale. And sadly, a lot of impressionable people will already accept the nonsense Watson said.