A report published in the Proceedings of the National Academy of Sciences this week provides new radiocarbon evidence pertaining to the Neanderthal refugium in the lower Iberian peninsula.
Neanderthal Sites North and South of the Ebro Frontier in Iberia. Base map: Tony Retondas.
For about 20 years or so, archaeologists and paleontologists have identified something on the order of 30 Neanderthal sites in Spain, Portugal and Gibraltar, all of which have returned radiocarbon dates of between 30,000 and 36,000 years ago: up to 10,000 years later than sites in the rest of Europe. The boundary between Europe--where Neanderthal sites are no younger than ~42,000 years old--and the Iberian peninsula--where more recent sites are found--is known as the Ebro Frontier, a biogeographical boundary that is thought to have represented a hindrance to Anatomically Modern Human colonization efforts, allowing Neanderthals to exist up into the Upper Paleolithic period.
What the new paper says is that all of those late dates may be wrong, that the radiocarbon dates were on degraded or contaminated organic materials, and there may never have been a Neanderthal refugium. The jury's still out: not all of the sites have been retested, and no doubt there's more work to be done, but it certainly throws a wrench into a long-standing theory about human colonization of our planet.
Wood R, Barroso-Ruiz C, Caparrós M, Jordá Pardo JF, Galván Santos B, and Higham TFG. 2013. Radiocarbon dating casts doubt on the late chronology of the Middle to Upper Palaeolithic transition in southern Iberia. Proceedings of the National Academy of Sciences Early Edition.