The Terminal Pleistocene Human Skull From Yahuai Cave: Craniofacial Morphological Variation and Complex Population History in Southern East Asia

Objective: The terminal Pleistocene is a crucial stage in the formation and differentiation of modern populations. Recent studies show that the population during this period had significant morphological variability and regional divergence. The objective of this study was to investigate the Yahuai-1 (YH1) from the Yahuai Cave site in southern China to understand human morphological diversity and population dynamics during the terminal Pleistocene in Southern East Asia. Materials and Methods: The YH1, which dated back to 16.0k years ago, was the main material of this study. The analytical approach involved a comprehensive comparison of both metric and non-metric craniomandibular traits of YH1. The comparison samples included those from the Late Pleistocene and Early Holocene, as well as recent-modern specimens from Asia and Oceania. Results: The YH1 cranium exhibits large overall size, substantial cranial capacity, and more developed craniomandibular superstructures. Multivariate analysis of craniometric traits reveals that YH1 is morphologically congruent with Maritime Southeast Asians, Polynesians, and Micronesians among recent and modern groups. Among ancient specimens, YH1 clusters more closely with Late Pleistocene fossils. The combined results of two multivariate analyses reveal YH1's craniofacial mosaicism, characterized by a larger, primitive facial skeleton juxtaposed with a derived neurocranial vault. Conclusion: (1) YH1 exhibits mosaic craniofacial traits, serving as an evolutionary transition between Late Pleistocene hominins and Holocene populations. (2) Around 16.0k years ago, the north–south differentiation in East Asian craniofacial morphology had not yet been completed. (3) YH1 may have contributed to the Austronesian-speaking populations' origin.