> Those two branches do live among Americans.

If you were not referring to extinct branches I don't know why you thought "they would likely represent two clusters" if they did not already in the clustering given.

> Afro-American people have the biggest genetic diversity in America and their genetic subgroups are so distinctive that they require separate testing in clinical studies.

Yes, and?

> I bet you won’t be able to tell the difference between them from their appearance though.

Maybe, and?

> Now good luck redefining the concept of race with this knowledge.

Good luck trying to deny biological race when you've just listed more evidence for it.