A new paper in PNAS, Palaeoproteomic evidence identifies archaic hominins associated with the Châtelperronian at the Grotte du Renne, weighs in the question of whether the Châtelperronian culture were Neandertals, with an answer in the affirmative in this case:
The displacement of Neandertals by anatomically modern humans (AMHs) 50,000–40,000 y ago in Europe has considerable biological and behavioral implications. The Châtelperronian at the Grotte du Renne (France) takes a central role in models explaining the transition, but the association of hominin fossils at this site with the Châtelperronian is debated. Here we identify additional hominin specimens at the site through proteomic zooarchaeology by mass spectrometry screening and obtain molecular (ancient DNA, ancient proteins) and chronometric data to demonstrate that these represent Neandertals that date to the Châtelperronian. The identification of an amino acid sequence specific to a clade within the genus Homo demonstrates the potential of palaeoproteomic analysis in the study of hominin taxonomy in the Late Pleistocene and warrants further exploration.
The details about stratigraphy are beyond me. But the protein and mtDNA evidence is pretty conclusive in my opinion that there are Neandertal individuals in this assemblage. Therefore, assuming their stratigraphy is correct, what you see in the Châtelperronian may be a cultural influence upon Neandertals by anatomically modern humans who were pushing into Europe at this time.
But cultural influence may not be the only dynamic at work. In The 10,000 Year Explosion: How Civilization Accelerated Human Evolution Greg Cochran hypothesized that Châtelperronian culture may have been a vector for Neandertal genes coming into modern human populations. And now we know that this isn’t always one directional. That is, just as modern humans absorbed genes from “archaic” populations, so archaic groups absorbed ancestry from modern populations (or at least humans closer to the main stem of modern humanity).
In The Third Chimpanzee Jared Diamond posited that the Châtelperronian Neandertals were analogous to native peoples in the New World such as the Cherokee, who adopted many aspects of European settler culture in their attempt to resist cultural absorption and marginalization. But one dynamic we need to remember about these tribes is that they also had a lot of European ancestry, in part because of the rapidly unbalanced population sizes. It seems entirely likely, as some have posited, that the last “Neandertal” populations were also substantially admixed. Therefore, it is not entirely surprising that they would also tend to exhibit cultural features more commonly found among modern humans.
My prediction is that when whole genomes of Châtelperronian Neandertals are available it is highly likely that they often show evidence of modern human ancestry.
Note: Diamond’s The Third Chimpanzee is in my opinion a very underrated work. It is a bit dated today, but I still think it is quite worth reading.