RESUMEN
Neanderthal populations of the southern and northern Caucasus became locally extinct during the Late Pleistocene. The timing of their extinction is key to our understanding of the relationship between Neanderthals and anatomically modern humans (AMH) in Eurasia. Recent re-dating of the end of the Middle Palaeolithic (MP) at Mezmaiskaya Cave, northern Caucasus, and Ortvale Klde, southern Caucasus, suggests that Neanderthals did not survive after 39 ka cal BP (thousands of years ago, calibrated before present). Here we extend the analysis and present a revised regional chronology for MP occupational phases in western Georgia, based on a series of model-based Bayesian analyses of radiocarbon dated bone samples obtained from the caves of Sakajia, Ortvala and Bronze Cave. This allows the establishment of probability intervals for the onset and end of each of the dated levels and for the end of the MP occupation at the three sites. Our results for Sakajia indicate that the end of the late Middle Palaeolithic (LMP) and start of the Upper Palaeolithic (UP) occurred between 40,200 and 37,140 cal BP. The end of the MP in the neighboring site of Ortvala occurred earlier at 43,540-41,420 cal BP (at 68.2% probability). The dating of MP layers from Bronze Cave confirms that it does not contain LMP phases. These results imply that Neanderthals did not survive in the southern Caucasus after 37 ka cal BP, supporting a model of Neanderthal extinction around the same period as reported for the northern Caucasus and other regions of Europe. Taken together with previous reports of the earliest UP phases in the region and the lack of archaeological evidence for an in situ transition, these results indicate that AMH arrived in the Caucasus a few millennia after the Neanderthal demise and that the two species probably did not interact.