Palaeoclimate in the Saharan and Arabian Deserts during the Middle Palaeolithic and the Potential for hominin dispersals
Palaeoclimate in the Saharan and Arabian Deserts during the Middle Palaeolithic and the Potential for hominin dispersals
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DOI：
10.1016/j.quaint.2012.12.018
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发表时间：
2013-06-25
影响因子：
2.2
通讯作者：
Parker, Adrian
中科院分区：
文献类型：
--
作者：
Drake, Nick A.;Breeze, Paul;Parker, Adrian
为了从撒哈拉以南非洲地区扩散出去，古人类必须穿越撒哈拉沙漠和/或阿拉伯半岛的沙漠。因此，了解撒哈罗-阿拉伯地区的古气候对于确定这些沙漠在地球人口中所扮演的角色至关重要。它们什么时候充当屏障，什么时候变得更加潮湿，从而打开了跨越它们的扩散路线？为了解决这些问题，我们使用组合概率密度函数（PDF）和地理信息系统（GIS）对所有使用铀/钍（U/TH）或光激发光（OSL）方法测年的地点进行了时间和空间评估，对20至350 ka的测年地点进行了时间和空间评估。由于该时间范围内的污染问题，未考虑放射性碳测年法。结果表明，在 MIS 2 期间，阿拉伯半岛几乎没有湿度的证据，正如在末次盛冰期的高度所预期的那样，然而，撒哈拉沙漠在 MIS 2 开始时显示出湿度的急剧上升，在 29 ka 时在 MIS 3 边界附近达到峰值。 MIS 3 和 6 似乎存在短暂的潮湿期，但撒哈拉沙漠（约 37、44、138,154 和 180 ka）和阿拉伯半岛（约 40、54 和 163 ka）的时间不同。在 MIS 5 期间，这两个地区都显示出大量湿度证据，PDF 峰值对应于日照最大值，尽管并非所有最大值都在撒哈拉或阿拉伯记录中出现。这种情况可以用偏心率调节进动来解释：当偏心率很强时，日照会增强（但变化也更大），沙漠气候通常会更加潮湿，特别是在日照较高的时候。当偏心率较低时，情况恰恰相反，沙漠往往更加干旱，但当地因素对气候的影响更大，影响短暂潮湿时期的时间和强度，因此它们不再与日照最大值一致。潮湿地点的空间分布与许多不同的现代人类扩散理论相一致。阿拉伯半岛南部经历了以 54 ka 和 125 ka 为中心的潮湿期，这可能促进了从东非通过曼德海峡传播到阿拉伯半岛南部以及更远的地区。在 MIS 5 期间，撒哈拉沙漠显示出大量湿度的证据，并且此时可能已经在其广阔的范围内扩散。 (C) 2012 Elsevier Ltd 和 INQUA。版权所有。
To disperse out of sub-Saharan Africa, it was necessary for hominins to cross the deserts of either the Sahara and/or Arabia. Thus, understanding the palaeoclimate of the Saharo-Arabian region is central to determining the role these deserts played in the peopling of the planet; when did they act as barriers and when were they more humid, opening dispersal routes across them? To address these questions we have conducted a temporal and spatial evaluation of dated sites from 20 to 350 ka using combined probability density function (PDF) and geographical Information System (GIS) analyses of all sites dated using uranium/thorium (U/TH) or optically stimulated luminescence (OSL) methods. Radiocarbon dates were not considered because of contamination problems in this time range. The results show that during MIS 2 there is little evidence for humidity in Arabia as would be expected during the height of the last glacial maximum, however, the Sahara shows a sharp rise in probability at the beginning of MIS 2, peaking near the boundary with MIS 3 at 29 ka. There appear to be brief periods of humidity in MIS 3 and 6, though at different times in the Sahara (ca. 37, 44, 138,154 and 180 ka) and Arabia (ca. 40, 54 and 163 ka). During MIS 5, both regions show much evidence for humidity, with PDF peaks corresponding to insolation maxima, though not all maxima are represented in either the Saharan or Arabian record. This situation can be explained by eccentricity-modulated precession: when eccentricity is strong, insolation is enhanced (but also more variable) and the desert climate is generally more humid, particularly at times of high insolation. The opposite happens when eccentricity is low, and deserts tend to be more arid, but local factors exert more of an influence on climate, affecting the timing and strength of the brief humid periods experienced, so that they no longer coincide with insolation maxima. The spatial distribution of humid sites is compatible with a number of different modern human dispersal theories. Southern Arabia experienced humid periods centred on 54 ka and 125 ka, and this could have facilitated dispersal from east Africa to southern Arabia and beyond via the Bab el Mandab. The Sahara shows considerable evidence for humidity during MIS 5 and may have had dispersal across its expanse at this time. (C) 2012 Elsevier Ltd and INQUA. All rights reserved.