Are Neanderthal Portraits Wrong?: Neanderthal Adaptations to Cold and Their Impact on Palaeolithic Populations

On the basis of comparisons between the relative thickness of the walls of Neanderthal limb bones to those of the average modern human and the observation that bone mass increases as modern individuals add weight, this thought-piece proposes redefi nitions of the appearance of cold-weather Neanderthals based on two biological adaptations to glacial climate. It suggests related biological and technological mechanisms for explaining the paucity of genetic or fossil evidence for extensive hybridisation between both early and recent Homo sapiens sapiens ('Moderns'), on the one hand, and northern and western 'classic' Neanderthals, on the other. Its 'insulation hypothesis' includes an explanation of why a population resulting from an admixture of Neanderthals and anatomically modern humans may have been constrained to the Levant between at least c. 120-92 ka bp (H. sapiens sapiens at Skhul and Qafzeh) and c. 45 ka (H. sapiens sapiens at Geula). It goes on to propose reasons for the replacement of the classic Neanderthal suite of features aft er H. sapiens sapiens and at least some Neanderthals began showing modern behavioural adaptations and encountered one another as Moderns spread into or developed in western Eurasia during the initial Upper Palaeolithic.