Neandertal to Modern Transition Full of Fits and Spurts

New evidence suggests that Neandertals survived longer on the Iberian peninsula than elsewhere in Europe.  The redating of the Zafarraya Neandertal from the late 20k’s to between 38 and 40 ky saw a revision of theories about Neandertal extinction. Now more evidence has been unearthed suggesting that this window is more secure.   From The Statesman:

Neanderthals may have survived at least 3,000 years longer than thought in what is now Spain – much after the species had died out everywhere else, a study has found.

The findings suggest that the process of modern human populations absorbing Neanderthal populations through interbreeding was not a regular, gradual wave-of-advance but a “stop-and-go, punctuated, geographically uneven history.”

Over more than ten years of fieldwork, researchers excavated three new sites in southern Spain, where they discovered evidence of distinctly Neanderthal materials dating until 37,000 years ago.

“Technology from the Middle Paleolithic in Europe is exclusively associated with the Neanderthals,” said Joao Zilhao, from the University of Barcelona in Spain.

“In three new excavation sites, we found Neanderthal artefacts dated to thousands of years later than anywhere else in Western Europe,” said Zilhao, lead author of the study published in the journal Heliyon.

It seems pretty clear now that the model of rapid replacement of Neandertals does not hold. This kind of evidence, along with sites such as Lagar Velho, suggest that the transition, at least in this region was long-term, with much hybridization.  We still do not know exactly how long Neandertals persisted in this region.  It makes perfect sense that they would have been the last ones to undergo the transition (however that happened) because the earliest Aurignacian sites, associated with modern humans, occur in far eastern Europe as the wave of moderns came through during the Würm I/Würm II interglacial.

The question that I have is why didn’t the earliest modern humans, represented by the Jebel Irhoud remains, come through the Strait of Gibraltar?  North of that, all you find are archaic, all the way down to the Zafarraya remains.  I wonder why this is.