Study Of Uranium Series Dating Of Late Homo Sapiens Sites In Southern China

For the past more than 20 years, the origin, dispersal and evolution of modern Homo sapiens have been the subjects of an intensive debate between the exponents of two competing hypotheses, "regional continuity" versus "recent out of Africa". Establishing a reliable chronological framework is essential to this study.Based on the U-series dating of intercalated speleothem formations, the chronology of several hominid sites in southern China has been studied.Longtanshan No. 1 Cave is located in the south of Chenggong County, Yunnan Province. Systematic excavations since 1977 have led to the discovery of 2 hominid teeth assigned to late Homo sapiens, mammalian fossils representing 12 species. The ~230Th/~234U dating has been carried out on 5 intercalated calcite and 5 fossil samples. The results from calcite samples are much too old to be compatible with the biostratigraphy, indicating an urgent need to re-study the complicated stratigraphic sequences. The fossil samples provide an age range between 60 and 80 ka, which may represent the chronology of the hominid teeth. However, compared with the well established U-series dating of speleothem calcites, the U-series dates on fossil materials tend to be much younger.Ganqian Cave, situated in Tubo District, Liujiang County, Guangxi Zhuang Autonomous Region were unearthed 17 hominid fossil teeth representing at least 13 individuals, is one of the numerous anthropologic cave sites in southern China. We have carried out ~230Th/~234U dating on intercalated calcite samples. The results show that the capping flowstone layer is of an age of 130 ka, and the second one 218 ka. The fossil-bearing deposits bracketed by the two flowstone layers should be of an age between 130 and 218 ka. ~230Th/~234U and ~227Th/~230Th dating on two mammal fossil teeth gave age ranging from 95 to 139 ka, which evidence the stratigraphic order between the capping flowstone and the underlying fossil-bearing deposits and support to the age assignment of older than ca. 100 ka to the hominid fossil teeth.The results show that these sites are much older than the previously estimated age of less than 40 ka. Taking into account the dating results on other sites having been studied previously in Yunnan and Guangxi Province, the appearance of modern H. sapiens in China may be an event as early as in West Asia and South Africa.