Lishui The Shenxian The Uranium Series Dating Study

The appearance of anatomically modern Homo sapiens is a hotly debated issue in paleoanthropology.Specialists and lay people alike tend to recognize two major models, i.e. "recent out of Africa" and "multiregional evolution". In China, there is a widely accepted "temporal gap" between 40-100 ka of human presence, which is recognized as an important evidence in favor of the "out of Africa" hypothesis. However, we thought it is only a artefact due to methodological imperfections.Shenxian Cave, located at ca. 21 km southeast to the town of Lishui county, is the first anthropologic site discovered in Jiangsu Province, eastern China. Systematic excavations in late 1970s led to the discovery of a temporal bone assigned to modern Homo sapiens together with mammalian fossils representing 22 species. Conventional ¹⁴C dating was performed on one specimen of "charcoal grains", yielding an age of 11,200±1,000 a B.P., which has been generally quoted as the age of the cave's fossil discoveries.In this paper we present ²³⁰Th/²³⁴U dates, ranging from 7 to 109 ka, on four mammalian fossil bones from museum collections of the site. Independent ²²⁷Th/²³⁰Th determinations on two of them give results consistent within errors with those from ²³⁰Th/²³⁴U, which is in support of the reliability of the obtained results. It is thus more reasonable to attribute the fossiliferous deposits to the above range, indicating a time span of at least 100 ka, than the previous estimate at～10 ka. However, in a cave setting compared with pure and dense speleothem calcites, fossil materials generally give younger U-series dates. So we tend to consider that the lowermost boundary of the cave's fossiliferous deposits should be late Middle Pleistocene in time, while the uppermost strata where the hominid fossil is believed to come from should be formed at the end of Late Pleistocene or in early Holocene.The results taking into account the dating results on other sites having been studied previously in Guangxi Zhuang Autonomous Region, Yunnan and Jiangsu Provience, for the under-estimated chronologies of Chinese Middle to Late Pleistocene sites, show that the site is much older than previously estimated age.The application of non-destructive gamma spectrometric U-series or direct AMS ¹⁴C dating may further constrain the age of the hominid fossil, which may provide important information on originate, migrate and evolution of the modern Homo sapiens.