Placing late Neanderthals in a climatic context

摘要

要将石器时代的事件与气候条件联系起来，因难以对距今大约21，000 年(用放射性碳测年方法测定的时间)前后的放射性碳测年记录进行 校正、以及缺乏一个关于气候事件年代的“总编年史”而受阻。但研 究人员有一个办法来绕过这一问题：放射碳年代可以通过优秀的 cariaco Basin深海记录与古气候记录联系起来。这样，欧洲“尼安德 特人”的消失就可以与已知的气候事件关联起来。将这一分析应用于 来自Gibralter的Gorham's Cave的“尼安德特人”原始工具，研究人员 发现，“尼安德特人”在一次大规模的环境变迁发生之前可能一直在 那里繁衍生息。%Attempts to place Palaeolithic finds within a precise climatic framework are complicated by both uncertainty over the radiocarbon calibration beyond about 21,500 ~(14)C years bp and the absence of a master calendar chronology for climate events from reference archives such as Greenland ice cores or speleothems. Here we present an alternative approach, in which ~(14)C dates of interest are mapped directly onto the palaeoclimate record of the Cariaco Basin by means of its ~(14)C series, circumventing calendar age model and correlation uncertainties, and placing dated events in the millennial-scale climate context of the last glacial period. This is applied to different sets of dates from levels with Mousterian artefacts, presumably produced by late Neanderthals, from Gorham's Cave in Gibraltar: first, generally accepted estimates of about 32,000 ~(14)C years bp for the uppermost Mousterian levels; second, a possible extended Middle Palaeolithic occupation until about 28,000 ~(14)C years bp; and third, more contentious evidence for persistence until about 24,000 ~(14)C years bp. This study shows that the three sets translate to different scenarios on the role of climate in Neanderthal extinction. The first two correspond to intervals of general climatic instability between stadials and interstadials that characterized most of the Middle Pleniglacial and are not coeval with Heinrich Events. In contrast, if accepted, the youngest date indicates that late Neanderthals may have persisted up to the onset of a major environmental shift, which included an expansion in global ice volume and an increased latitudinal temperature gradient. More generally, our radiocarbon climatostratigraphic approach can be applied to any 'snapshot' date from discontinuous records in a variety of deposits and can become a powerful tool in evaluating the climatic signature of critical intervals in Late Pleistocene human evolution.