广西柳江土博咁前洞的铀系年代

U-SERIES DATING OF HOMINID SITE GANQIAN CAVE AT TUBO, LIUJIANG,GUANGXI IN SOUTH CHINA

本文报道晚期智人化石地点广西柳江土博前洞新生碳酸盐岩和骨化石样的铀系测年结果。该地点表层钙板在约 94ka前开始形成 ,含化石粘土堆积叠压的钙板年代为约 2 2 0ka ,人牙化石应位于二者之间。二个动物化石样的二种铀系法年代范围为 85— 139ka ,表明该地点含化石堆积与表层钙板间无地层倒序现象 ,支持人牙化石大于 10 0ka的结论。邻近的柳江晚期智人化石地点和柳州白莲洞人类遗址铀系测年的结果与本文一致。具现代解剖特征智人在中国南方出现的时间 ,很可能不晚于西亚和非洲。在现代人类起源方面 ,中国不应是远离中心。

Ganqian Cave, located at Tubo District, Liujiang County, Guangxi Zhua ng Autonomous Region is one of the numerous anthropologic cave sites in southern China. From the cave infilling a total of 17 hominid fossil teeth have been co llected, 5 of them in situ by the excavators and others by amateurs. The as soci ated mammalian fossils represent 22 species, all common members of the Late Plei stocene Ailuropoda Stegodon fauna.230Th/ 234 U dating has been carried out on intercalated calcite s amples. The capping and the 2 nd flowstone layers are dated to ca. 94 and 220 ka respectively. The fossil bearing deposits are bracketed by the two flowstone layers and shoul d therefore be of an age between 94 and 220 ka. The parallel 230Th / 234U and 227 Th/230 Th dating on two mammal fossil teeth gave age results ranging from 85 to 139 ka, which evidence the stratigraphic order be tween the capping flowstone and t he underlying fossiliferous layer and hence lend support to the age assignment o f older than ca.100 ka to the hominid fossil teeth. The Tubo hominid fossils have been widely accepted by Chinese paleoanthropologis ts as representatives of late Homo sapiens. If so the aforementioned dates impl y a presence of anatomically modern Homo sapiens in southern China much earlier than previously thought. U series dating has also been performed on neighborin g Liujiang and Bailiandong hominid sites, the results indicating also an early pr esence 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 s c enario 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 tha t 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 c ave as well as on other paleoanthropological sites in southwestern China are war ranted for important evidence regarding the origin and evolution of modern human species in East Asia may be found.