Cro-Magnon 1, dating and mtDNA

I’m running through the new paper from Qiaomei Fu and colleagues Fu:revised:2013 about Upper Paleolithic mtDNA genomes. Probably several readers were wondering, as I did, about this passage in the paper concerning Cro-Magnon 1:

The exception was the Cro-Magnon 1 sample, which belonged to the derived hg T2b1, an unexpected hg given its putative age of 30,000 years [16]. Since the radiocarbon date for this specimen was obtained from an associated shell [16], we dated the sample itself using accelerator mass spectrometry (AMS). Surprisingly, the sample had a much younger age of about 700 years, suggesting a medieval origin. Consequently, this bone fragment has now been removed from the Cro-Magnon collection at the Muse de lHomme in Paris. Attempts to directly date other remains from the Cro-Magnon type collection unfortunately failed. The good molecular preservation of our sample for both DNA and AMS dating, in contrast, suggests that this particular bone has a different origin from the other remains in the collection.

Cro-Magnon 1 is one of the most recognizable Upper Paleolithic cranial specimens from Europe, and its date has often been questioned – largely because the very early excavation of this site by Louis Lartet came early in the history of European prehistory, when many excavations proceeded without appreciating the stratigraphic complexities of sites.

I have checked with Alain Froment and Johannes Krause on the status of this bone. The bone sample was taken from a tibia fragment that was not clearly associated with the rest of the collection. None of the Cro-Magnon human remains has yet yielded a radiocarbon date, and Alain indicates that the organic carbon is gone. So the current paper does not challenge the Cro-Magnon date, it merely subtracts an intrusive element.