Trace element analysis of ochre for modern and prehistoric pigment source use patterns

依赖符号来传达信息和标记身份是现代人的一个基本属性。使用红色和黄色赭石颜料作为象征是人类文化行为中最广泛和持久的。然而，由于缺乏明显的象征性应用，如洞穴或岩石艺术，如何解释这种铁基颜料的模糊性，阻碍了考古赭石的研究。这个项目结合了考古学，地质学和人种学的方法来调查史前到现代使用赭石颜料。调查人员已经对肯尼亚的马赛人和桑布鲁人进行了采访，他们中的许多人在日常生活中仍然使用赭石，并确定了这些群体用于象征性和功能性目的的赭石矿物的露头。地球化学技术被证明可以有效地区分来自不同来源的赭石，将用于分析从赭石矿床收集的样本，并将它们与该地区岩石艺术遗址的油漆样本和考古遗址的赭石文物进行匹配。该项目将改进破坏性最小的方法，用于分析赭石和其他含铁材料的成分，用于人类学、地质学、材料科学和法医应用。改进确定赭石颜料和相关材料的地理和地质来源的技术，对查明被掠夺的文物和赝品具有重大意义。该项目还将通过博物馆外展、国际合作以及为代表性不足的少数民族学生提供STEM科学方面的指导，为公众科学教育提供机会。最近在石器时代考古遗址中发现的赭石颜料揭示了人类符号行为的巨大时间深度。利用新的地球化学技术研究赭石的来源，特别是电感耦合等离子体质谱法的最小破坏性微量元素指纹图谱，增强了我们对古代颜料符号的进化意义和潜在意义的理解。该项目在过去十年中对该方法进行了改进，创建了肯尼亚裂谷居民目前或最近使用的赭石来源的微量元素和稳定同位素（锶、铅和铁）指纹数据库。马赛人和桑布鲁人是东非少数几个保留着活跃的岩石艺术和赭石自我装饰传统的民族。它们为研究现代人类如何以象征性的目的与地质环境相互作用提供了最好的机会。一旦完成，来源数据库将用于通过在实地和博物馆研究中取样的最近起源来确定石器时代的赭石文物和岩石艺术颜料的地质来源。这将允许调查关于象征性中介与最低成本（最近来源）矿床开采模式的假设，赭石颜料的运输和贸易，以及特定颜料颜色的优先使用。此外，源指纹数据库将在网上免费提供，供其他科学家在项目完成后在自己的研究中使用。

Dependence on symbolism to communicate information and mark identities is an essential attribute of modern humans. The use of red and yellow ochre pigments for symbolic purposes is among the most widespread and persistent of human cultural behaviors. However, the study of archaeological ochre has been hindered by ambiguity over how to interpret this iron-based pigment in the absence of obvious symbolic applications such as cave or rock art. This project combines archaeological, geological, and ethnographic methods to investigate prehistoric through modern use of ochre pigments. The investigators have already conducted interviews with the Maasai and Samburu peoples of Kenya, many of whom still use ochre in their daily lives, and identified outcrops of ochre minerals that these groups exploit for symbolic and functional purposes. Geochemical techniques proven to be effective at telling apart ochre from different sources will be used to analyze samples collected from ochre deposits, and to match them to paint samples from rock art sites and ochre artifacts from archaeological sites in the region. This project will refine minimally destructive methods that can be used to analyze the composition of ochre and other iron-containing materials for anthropological, geological, materials science, and forensic applications. Improving techniques for determining the geographic and geologic origin of ochre pigments and related materials has significant implications for identifying looted heritage items and forgeries. The project will also provide opportunities for public science education via museum outreach, international collaborations, and mentoring in the STEM sciences for underrepresented minority students. Recent discoveries of ochre pigments from Stone Age archaeological sites have shed light on the great temporal depth of human symbolic behavior. Our understanding of the evolutionary significance and potentially the meaning of ancient symbolism using pigments has been enhanced by novel geochemical techniques for provenance studies of ochre, particularly minimally destructive trace element fingerprinting by Inductively Coupled Plasma - Mass Spectrometry. The project builds on improvements in this method over the last decade by creating a database of trace element and stable isotope (strontium, lead, and iron) fingerprints for ochre sources currently or recently used by inhabitants of the Kenya Rift Valley. The Maasai and Samburu are among the few remaining peoples in East Africa with active rock art and ochre self-adornment traditions. They present the best opportunity for studying how modern humans interact with their geologic environment for symbolic purposes. Once completed, the source database will be used to determine the geologic provenance of ochre artifacts and rock art paints of Stone Age through recent origin that were sampled during field and museum research. This will allow for investigation of hypotheses about symbolically mediated versus least-cost (nearest source) models of mineral deposit exploitation, transport and trade of ochre pigments, and preferential use of specific pigment colors. In addition, the source fingerprint database will be made freely available online for other scientists to use in their own research upon completion of the project.