"Here are the estimates of ancestral quanta for African Americans by region against different potential ancestral groups. They had 136 African Americans, so I wouldn’t put too much weight on the interregional differences."

136 people in the group...HARDLY a study...

"Overall, nothing too new in the paper, but really great charts!"

I agree with the writer of the story...

I don't care about african americans and their particular ancestry...I want to know WHY:

"In contrast, white ancestry does exhibit a great deal of individual variation."

And your article does NOT say. It say's: "much of the ancestry may be much more recent. Recent ancestry has less time to be “dispersed” across the population through intermarriage." That's no explanation.