I recently remarked on a scientist's announcement that up to four percent of the DNA of people living outside Africa in Eurasia came from Neandertals. Of course that finding has to replicated, and it is sure to be hotly debated. Biological- and paleo-anthropologists have argued among themselves for years over whether Neandertals were an archaic subgroup of humans or were a separate species. (If they were a subgroup of Homo sapiens, they could interbreed and produce fertile offspring.)
It turns out that the debate will be broader than that. There long has been a sharp divide between those argue on the basis of fossils that humans mated with Neandertals in Eurasia and with the descendents of Homo erectus hominids who had migrated to East Asia at least 100,000 years earlier. Others opposed to this "multiregional evolution theory" of modern human origins say hogwash. These "out of Africa" types insist that humans arose solely in Africa and when they finally migrated elsewhere, they could only breed with their own kind. Their point is that evolution of a species doesn't work that way - it is too random and contingent to happen the same way in widely separated places.
Whatever the outcome of these mysteries, my reading has solved a tiny little mystery of my own.
For years, I have wondered why some authors would talk about humans as Homo sapiens, while others would use the label Homo sapiens sapiens. Well, it seems that if Neandertals really are a subspecies of humans, then they should be called Homo sapiens neadertalensis. Thus humans must have the second sapiens. The authors have been taking sides all along!