Amino Acid Racemization Dating of the Middle Stone Age of Africa: Improvement of Precision with Ostrich Eggshell

这项研究的目的是开发非洲考古遗址的年代测定技术，这些遗址太老，无法用放射性碳测年(距今45000年)，而且缺乏适当的火山物质来进行高精度的Ar-Ar测年。这些方法还可能有助于解决考古遗址的年代学和干扰问题。如果我们要了解现代人的非洲起源和现代行为的起源等问题，这种年代化的解决方案是必不可少的，这两个问题都可能追溯到中更新世晚期和上更新世(距今40,000-200,000年)，以及相关的中石器时代文化。拟议的研究将通过分析坦桑尼亚、博茨瓦纳、纳米比亚和南非六个非洲遗址的温度时空变化模式，提高鸵鸟蛋壳(考古遗址中较常见的材料之一)氨基酸外消旋测年的精确度。对这些地点更新世温度历史的了解还将表明每个地区(热带和温带)如何反映晚更新世期间的全球变冷和变暖模式，并能够评估人类对这些气候变化的反应。

This research is aimed at developing dating techniques for African archaeological sites that are too old to be dated by radiocarbon (45,000 years before present) and which lack appropriate volcanic materials for high-precision argon-argon dating. The methods may also help to resolve problems of chronology and disturbance in archaeological sites. Such chronological resolution is essential if we are to understand such issues as the African origins of modern humans and the origins of modern behavior, both of which may relate back to the time period of the late Middle and upper Pleistocene (40,000-200,000 years before present) and the associated Middle Stone Age culture. The proposed research would improve the precision of amino acid racemization dating of ostrich eggshell (one of the more common materials in archaeological sites), through analysis of patterns of spatial and temporal variation in temperature at six African sites in Tanzania, Botswana, Namibia and South Africa. Knowledge of the Pleistocene temperature histories of these sites will also indicate how each region (tropical vs. temperate zones) reflected global cooling and warming patterns during the late Pleistocene and allow evaluation of human response to these climatic variations.