Redewenur wrote:

"Presumably that means 'different populations' of Homo sapiens, and not a genetic convergence of earlier species."

It would be my guess it means the latter. Possibly going back to H. erectus. Different groups of humans have been moving round the earth and interbreeding with each other in historic times and I see no reason why the phenomenon wouldn't go back to to the first expansion of erectus. It would certainly account for all the evidence currently available, including the DNA evidence. It also seems to be the way all other species evolve but many people like to believe we humans are somehow special.