A clothing-microclimate hypothesis for the rapid selective sweep of EDAR V370A in Late Pleistocene northern Asia

The derived EDAR V370A allele experienced one of the strongest selective sweeps in recent human evolution, reaching near-fixation in East Asian and Native American populations within approximately 20,000 years. Despite extensive study, no single environmental pressure convincingly explains both the intensity and the abrupt cessation of selection after the Last Glacial Maximum (LGM). Here I propose that the sudden adoption of highly insulating but poorly ventilated tailored fur clothing (documented archaeologically from approximately 32–18 ka in northern East Asia and Beringia) created a novel microclimatic stress inside garments — impaired evaporative cooling and risk of sweat freezing against skin. The pleiotropic effects of EDAR 370A (increased eccrine gland density with smaller droplets, thicker straighter hair, reduced sebaceous activity) would have the potential to alleviate this stress and are temporally and geographically coincident with the sweep. Selection relaxed in the early Holocene as clothing technology shifted toward lighter, layered, and more breathable designs. This hypothesis accounts for the exceptional selection coefficient (approximately 0.09), its confinement to the Beringian/north-Asian LGM refugium, and the allele’s subsequent neutral behaviour during Holocene migrations.