Though we don’t know why. (The pop science version, we may recall, is that other human groups simply killed them off.):
The researchers examined over 5,000 remains of Châtelperronian tools from a site called Aranbaltza II in Barrika, in the Northern Iberian Peninsula, dating to around 45,500 years ago. Comparing this site with other nearby Neandertal tool sites, they document that the Châtelperronian system does not overlap in time with older Neandertal technologies in this region, suggesting that Châtelperronian tools were not developed from earlier Iberian technology, but instead originated elsewhere before migrating into the region. They also found that Châtelperronian tools appear earlier than the first Homo sapiens tools in the Iberian Peninsula.
Based on this evidence, the authors suggest that older Iberian Neandertal populations disappeared, taking their tool styles with them, and were replaced by different Neandertal groups using Châtelperronian tools, likely migrating from France, and these populations were in turn replaced by Homo sapiens. The researchers propose that these patterns of local Neandertal extinction and replacement will be an important area of future study, as they might have played a significant role in the decline and ultimate demise of Neandertals.
The authors add: “Neandertals with Châtelperronian technology occupied the Northern Iberian Peninsula ca. 43,000 years ago. This territory was unoccupied at the time, following the earlier disappearance of local Neandertal groups, along with their Mousterian technology.”
PLOS, “Tools reveal patterns of Neandertal extinction in the Iberian Peninsula” at ScienceDaily (March 30, 2022)
The paper is open access.
You may also wish to read: Neanderthal Man: The long-lost relative turns up again, this time with documents