Knowing that someone has substantial Ashkenazim ancestry lets you make many probabilistic predictions about both neutral and significant genetic variations
Yes, that's what I meant - they're an actually close-knit genetic group. "Negro" is not. "Black American" is a little closer, but not much (their African ancestors having been taken as slaves mostly from the west coast) - you'll see obviously highly selected-for factors, like black skin and sickle-cell.
There are people who identify as black or who are identified as black under a "one drop" rule. This doesn't seem as though it would give huge amounts of information about associated traits.
Please remember to have no heroes or villains, but this just looks plain bad to be honest. I'm lowering my estimation of the quality of Stephen J. Gould's work in this area.
USA today:
Haha. Humans.
The paper itself: