Confirmation of Neanderthal/modern human interstratification at the Chatelperronian type-site

The nature of the replacement of Neanderthal by anatomically and behaviorally modern populations in Europe is currently a topic of lively debate in human evolution. In an earlier paper [Gravina B, Mellars P, Bronk Ramsey C (2005) Nature 483:51-56], we published a series of radiocarbon accelerator mass spectrometer measurements for the site of Châtelperron in central France, which had been claimed to show a clear "interstratification" of successive levels of Neanderthal and modern human occupation, on the basis of excavations carried out by Henri Delporte in the 1950s. This interpretation has recently been challenged by Zilhão and colleagues [Zilhão J, d'Errico F, Bordes J-G, Lenoble A, Texier J-P, Rigaud J-P (2006) Proc Natl Acad Sci USA 103:12643-12648], who suggest that the deposits excavated in the 1950s consisted largely, if not entirely, of the unstratified "backdirt" of the earlier, 19th century excavations on the site. We show here that the excavation backdirt interpretation for the Châtelperron stratigraphy can be refuted from many different aspects of the stratigraphic, radiocarbon, and archaeological evidence. We reassess the significance of this site for current models of the coexistence and interactions between Neanderthal and anatomically modern populations in western Europe.