The Neandertal EnigmaFrayer's own reading of the record reveals a number of overlooked traits that clearly and specifically link the Neandertals to the Cro-Magnons. One such trait is the shape of the opening of the nerve canal in the lower jaw, a spot where dentists often give a pain-blocking injection. In many Neandertal, the upper portion of the opening is covered by a broad bony ridge, a curious feature also carried by a significant number of Cro-Magnons. But none of the alleged 'ancestors of us all' fossils from Africa have it, and it is extremely rare in modern people outside Europe." [pp 126-127]
by James Shreeve
“But none of the alleged ‘ancestors of us all’ fossils from Africa have it, and it is extremely rare in modern people outside Europe.” [pp 126-127]”
So, the folk who stayed behind in Europe are descended from Neanderthals, and the rest of us are descended from modern humans?
That explains a lot.