Neandertal Cold Adaptation: Technological, Anatomical, and Physiological Responses to Cold Stress in One of Our Closest Fossil Relatives.

Neandertals occupied western Eurasia for over 100 000 years, repeatedly enduring climates that ranged from seasonally cold to glacial. This paper reexamines the question of Neandertal cold adaptation using updated fossil, physiological, and archaeological evidence. While some populations lived outside glacial extremes, all faced periodic cold stress, and their survival depended on a diverse set of strategies. Technological buffers, including fire use, hide processing tools, and possible clothing and footwear, likely played a primary role in reducing cold exposure. Anatomically, Neandertals exhibit high body mass, broad trunks, and abbreviated limbs, consistent with thermoregulatory principles. The Neandertal nasal region, long considered paradoxical, now appears well suited to cold-dry air-conditioning; computational fluid dynamics and new endoscopic data support a functionally integrated nasal cavity with substantial internal surface area. Physiological adaptations remain inferential but plausible, including elevated basal metabolism, energy-dense diets, and potential use of brown adipose tissue. These factors likely contributed to high total energy expenditures, enabling thermoregulation in demanding environments. Rather than a single trait or "signature" adaptation, Neandertals present an integrated response to cold stress shaped by geography, development, culture, and genetics. This holistic view reframes Neandertal biology as deeply thermally engaged and sets the stage for targeted tests of function and mechanism in future research.