Regarding the origin of modern humans, a long-standing debate persists between the “Out of Africa” single-origin model and the “Multiregional Evolution” hypothesis. The former has encountered significant difficulties in explaining the continuity of the hominin fossil record in East Asia. This paper contends that the crux lies less in the paucity of fossil evidence than in the adaptationist presuppositions underlying conventional Darwinian frameworks. Bridging the gap between molecular and macroscopic realms, this paper introduces Kimura’s neutral theory into hominin morphology. It systematically argues that the high-frequency continuity of shovel-shaped incisors in East Asia over a million years is not a “medal” of natural selection, but a “signature” of genetic drift and founder effects. By falsifying the “adaptive advantage” of shovel-shaped incisors through biomechanics, paleoclimatology, and molecular biology, and combining this with evidence of East Asian geological isolation and stratigraphic continuity, this paper establishes the legitimacy and explanatory power of the neutral theory at the level of macroscopic morphology. Consequently, it provides a solid mechanistic foundation for the “continuity with hybridization” hypothesis of East Asian hominins and delivers a fundamental theoretical deconstruction of the single-origin model.
Jing Zhang (Wed,) studied this question.