The Climatic Framework of Neandertal Evolution
Neandertals represent the best documented group of Middle to Late Pleistocene archaic hominins. They are best documented in western Europe but have also been present at some point in their evolution in the Levant, central Asia and some parts of southern Siberia. There is growing evidence that their evolutionary trajectory started much earlier in time than was previously thought. The paleontological record is quite scarce when considering the earliest peopling of Eurasia, and in general populations pre-dating the rise of the Neandertals. However, climatic conditions seem to have had considerable influence in modulating the colonization processes of the middle latitudes of Eurasia. Some aspects of the Neandertal anatomy have been tentatively related to cold adaptation. There is little evidence of Neandertal presence in periarctic environments but cultural buffering in response to climatic stress was likely limited among these hominins. Recent advances in paleogenetics have also allowed us to better understand the demographic profile of archaic humans in Eurasia. It is proposed that considerable changes in the amplitude and length of the climatic cycles in the course of the last half million years played a major role in triggering the evolutionary divergence between human populations living north and south of the Mediterannean. Isolation and successive demographic crashes might have been a powerful engine explaining the rapid emergence of the Neandertals.