Late Pleistocene population interaction in western Europe and modern human origins: New insights based on the faunal remains from Saint-Cesaire, southwestern France

The present analysis tests the "Neandertal Replacement model" and seeks to reassess the assumptions of a demic expansion of early modern humans into Western Europe at the Middle to Upper Paleolithic boundary. More specifically, propositions are formulated about the ecological consequences of a modern human incursion into southwestern France. It is argued that late Pleistocene populations were kept close to the carrying capacity of the environment and were vulnerable to significant fluctuations in resource abundance, in particular during the snow-covered season. If the hypothesis of a modern human expansion into Eurasia during the Middle to Upper Paleolithic transition is true, it can be suggested that this significant demographic growth increased local populations far beyond carrying capacity and led to chronic resource depression. Therefore, it is suggested that these stresses lead Neandertals and early modern humans to adapt in order to cope with resource scarcity. Several lines of evidence, all related to fauna, are used to verify these propositions. These are linked to maximization of carcass utilization, changes in frequencies of low and high utility parts, of high and low-ranked taxa, marrow exploitation of low utility parts, and the importance of scavenging. These archaeological expectations are tested on eight faunal assemblages from Saint-Cesaire (Charente-Maritime), a site documenting the transition from the Middle to the Upper Paleolithic in southwestern France.; Although food stress is evidenced at Saint-Cesaire, it seems that fluctuations associated with resource exploitation were of similar amplitude throughout the sequences or, at least, that these fluctuations were not important enough to alter the equilibrium of the food procurement system and bring about changes in subsistence strategies. These results are not consistent with the implications derived from the replacement model. As a result, the hypothesis of a modern human migration causing the extinction of Neandertal populations appears to be refuted. An in situ evolution of local populations is argued to be a more likely explanation for the Middle to Upper Paleolithic transition.