A Re-evaluation of Hominin Depilation Timing: A Late Pleistocene Hypothesis Based on Interdisciplinary Evidence Integration

The prevailing 'deep-time' hypothesis, which places hominin depilation at 1.2 Mya as an adaptation for endurance running, suffers from profound incongruities with multidisciplinary evidence.This paper challenges this established view through a critical, interdisciplinary synthesis of the available evidence. We systematically deconstruct the substantial discrepancies within molecular clock analyses (e.g., a >400% variance in chronologies derived from the MC1R gene), the indirect and equivocal nature of paleopathological data, and the million-year "technological vacuum" separating the proposed depilation event from the advent of critical enabling technologies, including portable water apparatus, tailored clothing, and structured hearths. In response to these evidentiary conflicts, we propose an alternative theoretical framework, which we term the "Late Pleistocene Survival Strategy Hypothesis." This hypothesis posits that hominin depilation was not an event of deep antiquity but a far more recent adaptive phenomenon of the Late Pleistocene (ca. 100-50 kya). Its principal driver was the extreme thermoregulatory stress imposed by high-frequency, long-distance "day-roundtrip" locomotion—a behavioral necessity dictated by the expansion of foraging radii following megafaunal decline, a shift biomechanically reflected in the hominin skeleton. This profound physiological transformation was contingent upon a crucial "cultural-technological compensation package," encompassing proficient pyrotechnology and innovations in clothing and hydrational logistics. This model not only offers a more parsimonious unification of disparate evidence but also presents a novel heuristic for interpreting the Agricultural Revolution: not as a teleological "progression," but as a strategic "adaptive retreat" from a collapsed, high-expenditure subsistence regime.