Fig. 1. The human remains from Zhiren Cave. The Zhiren 3 mandible in anterior (A), lateral left (B), and superior (C) views. The midsymphyseal cross-section of the Zhiren 3 mandible (D). The Zhiren 1M3 in buccal and mesial views (E), and the Zhiren 2 M3 in the same views (F). (Scale bar, 5 cm.) (Courtesy of Drs. LIU Wu and JIN Chang-Zhu)

The 2007 discovery of fragmentary human remains (two molarsand an anterior mandible) at Zhirendong (Zhiren Cave) in SouthChina provides insight in the processes involved in the establishmentof modern humans in eastern Eurasia. The human remainsare securely dated by U-series on overlying flowstones and a richassociated faunal sample to the initial Late Pleistocene, >100 kya.Therefore, they are the oldest modern human fossils in East Asia andpredate by >60,000 y the oldest previously known modern humanremains in the region.

The research was reported in the Oct. 25, 2010 online early edition of the Proceedings of the National Academy of Sciences by Drs. LIU Wu, JIN Chang-Zhu, ZHANG Ying-Qi, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, and their collaborators from China and North America.

The Zhiren 3 mandible in particular presents derived modern human anterior symphyseal morphology, with a projecting tuber symphyseos, distinct mental fossae, modest lateral tubercles, and a vertical symphysis; it is separate from any known late archaic human mandible. However, it also exhibits a lingual symphyseal morphology and corpus robustness that place it close to later Pleistocene archaic humans.

The age and morphology of the Zhiren Cave human remains support a modern human emergence scenario for East Asia involving dispersal with assimilation or populational continuity with gene flow. It also places the Late Pleistocene Asian emergence of modern humans in a pre-Upper Paleolithic context and raises issues concerning the long-term Late Pleistocene coexistence of late archaic and early modern humans across Eurasia.

“It is in particular the anterior symphyseal morphology of the Zhiren 3 mandible, with its distinctly projecting tuber symphyseos, associated mental fossae, and modest lateral tubercles that aligns it with the derived morphology of early and recent modern humans. These features nonetheless occur in the context of a robust mandibular corpus,”said Dr. LIU Wu..

“These fossils therefore support previous populational scenarios for the emergence of modern humans that include populational continuity (to whatever degree) and admixture in East Asia, a version of the Assimilation Model. They indicate that the appearance of modern human biology in portions of western and eastern Eurasia occurred in the early Late Pleistocene, long before the appearance of Upper Paleolithic (sensu lato) behavioral complexes. They also further raise the question, long apparent for the western Old World, as to behavioral parameters underlying the apparent geographic separation of morphologically late archaic versus early modern human populations for tens of millennia,” said Dr. WU Xin-Zhi, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences.

"These fossils are helping to redefine our perceptions of modern human emergence in eastern Eurasia, and across the Old World more generally," says Eric Trinkaus, PhD, the Mary Tileston Hemenway Professor in Arts & Sciences and professor of physical anthropology.