关键词: 土博人类化石; 新生碳酸盐岩; 铀系年龄; 现代人类起源; 咁前洞

Abstract: Ganqian Cave, located at Tubo District, Liujiang County, Guangxi Zhuang Autonomous Region is one of the numerous anthropologic cave sites in southern China.From the cave infilling a to- tal of 17 hominid fossil teeth have been collected, 5 of them in situ by the excavators and others by amateurs.The associated mammalian fossils represent 22 species, all common members of the Late Pleistocene Ailuropoda-Stegodon fauna.
230Th/234U dating has been carried out on intercalated calcite samples.The capping and the 2nd flowstone layers are dated to ca.94 and 220 ka respectively.The fossil-bearing deposits are bracketed by the two flowstone layers and should therefore be of an age between 94 and 220 ka.The parallel 230Th/234U and 227Th/230Th dating on two mammal fossil teeth gave age results ranging from 85 to 139 ka, which evidence the stratigraphic order between the capping flowstone and the underlying fossiliferous layer and hence lend support to the age assignment of older than ca.100 ka to the hominid fossil teeth.
The Tubo hominid fossils have been widely accepted by Chinese paleoanthropologists as represent- atives of late Homo sapiens. If so the aforementioned dates imply a presence of anatomically modern Homo sapiens in southern China much earlier than previously thought. U-series dating has also been performed on neighboring Liujiang and Bailiandong hominid sites, the results indicating also an early presence of modern humans in the region.Taken together, the appearance of modern humans in East Asia and in Levant and Africa may be quasi-contemporaneous, a scenario in line with the hypothesis for morphological and cultural continuity in human evolution in China.
However, as the Tubo hominids are represented only through isolated teeth, their exact phylogenetic position can hardly be confirmed. Even if the Tubo hominids should be classified to Early Homo sapiens, the results of this paper imply that more than 100 ka ago, inhabitants in southern China bear distinctive features of modern morphology. So China should not be a retarded area in human evolution where all the previous populations were replaced.Further studies on Ganqian cave as well as on other paleoanthropological sites in southwestern China are warranted for important evidence regarding the origin and evolution of modern human species in East Asia may be found.

Key words: Tubo hominid; U-series dating; Speleothem calcite; Anatomically modern Homo sapiens; Ganqian Cave