Investigating raw material selection for stone tool making with material sciences

对石器制作原料的研究对我们了解过去的人类有着重要的意义。具体来说，随着时间的推移，石器原材料谱的变化被解释为流动性、经济或技术驱动选择变化的标志。两个南非中石器时代（MSA）遗址，Diepkloof Rockshelter和Sibudu Cave (~100-50 ka)，特别好地记录了整个序列的这种变化。这些变化是否反映了不同原材料可及性的变化，或者是地域的变化？或者，另一种选择是，南非MSA后期的采集者专门选择了制作工具的原材料吗？这些问题可以通过调查制造和/或使用特定工具的不同原材料的质量是否与它们的优先选择相关来回答。本研究项目的目的是通过研究与刀具扣接（扣接质量）和使用（耐磨性和冲击裂缝形成）相关的机械性能来阐明这些相关性。Diepkloof和Sibudu采集者在原料供应过程中实际做出的选择将根据机械数据的结果进行解释。为此，我们开发了一种基于材料科学的量化压扣质量和压裂可能性的新方法。通过使用这个新模型，结合定量使用实验，该项目试图揭示一些驱动工具石选择的基本机制，这对早期现代人类的进化至关重要。

The study of raw materials for stone tool making has important implications for our understanding of past people. Specifically, changes in the spectrum of stone tool raw materials through time have been interpreted as markers of changing mobility, economy or technology-driven selection. Two South African Middle Stone Age (MSA) sites, Diepkloof Rockshelter and Sibudu Cave (~100-50 ka), document such shifts throughout their sequence particularly well. Do these changes reflect changing accessibility of different raw materials, perhaps changing territoriality? Or, alternatively, did the foragers of the later part of the South African MSA specifically selected raw materials for tool making? These questions can be answered by investigating whether the qualities of different raw materials for making and/or using specific tools are correlated with their preferential selection. The aim of this research project is to shed light on these correlations by studying the mechanical properties relevant to tool knapping (knapping quality) and use (resistance to abrasion and impact fracture formation). The choices Diepkloof and Sibudu foragers actually made during raw material provisioning will be interpreted in the light of the results of the mechanical data. For this, we have developed a new method for quantifying Knapping quality and the likelihood of fracturing, based on material science. By using this new model, combined with quantitative use-experiments, this project seeks to uncover some of the fundamental mechanisms that drive tool stone selection at a time that is crucial to the evolution of early modern humans.