Collaborative Research: Development and Application of Cryptotephra Studies to Resolve Debates over Chronology in Modern Human Origins Research in South Africa

内华达州拉斯维加斯大学的尤金史密斯博士和亚利桑那州立大学的柯蒂斯马里恩博士沿着与一个国际科学家小组将应用一种新的测年方法来确定一套独特的人类特征何时首次出现在进化史上，从而帮助理解人类谱系何时、何地以及为什么进化。 南非中石器时代（MSA）遗址在这项工作中占有突出地位，通过推动和丰富科学认为人类决定性的关键特征的时间知识，彻底改变了现代人类起源的知识。 现代测年技术及其在考古遗址上的应用为确定早期人类历史上的关键事件发生时间提供了基础。 这些技术使用复杂的模型，产生年龄估计值，而不是绝对日期。 过去，不同的实验室使用不同的模型，可能会导致同一地质单元的年龄不同。 这引起了一场年代争议，降低了人们对早期人类史前史关键事件发生时间的信心。人们普遍认为，产生可靠的年龄估计的最佳方法是使用几种独立的测年技术。 最近，研究小组在南非Pinnacle Point的早期人类居住的岩石庇护所中发现了火山灰，这些火山灰的化学成分最适合印度尼西亚Toba火山75，000年前的喷发。这一发现提供了一个独立的测年工具，可以与传统的测年方法一起沿着使用，以解决测年争议，并将保存在尖峰点和南部非洲其他地区的人类起源记录与现代人类起源的全球记录联系起来。史密斯博士和马里恩博士及其研究小组将从南部非洲的四个考古遗址收集和处理样本，以识别和确定多巴火山喷发的火山灰分布。 这项工作将首次将这些地点记录的早期人类历史与一个单一的约会模型联系起来，并消除任何关于早期人类发展关键事件时间的争论。 火山灰与火山源的相关性将利用火山灰的化学性质来完成。 灰是非常小的（微米大小）玻璃颗粒的形式，称为碎片。 这些颗粒通过仪器进行分析，这些仪器将小直径的电子束或激光束聚焦在碎片上，以确定它们的化学成分。 然后将化学成分与已知化学成分的数据库进行比较，以确定灰烬的来源和年龄。 该项目不仅将为考古遗址提供新的独立测年工具，还将帮助培训学生和早期职业科学家掌握考古学和地质学技术。

Dr. Eugene Smith of the University of Nevada Las Vegas and Dr. Curtis Marean of Arizona State University along with an international team of scientists will apply a new dating method to determine when a suite of uniquely human features first appeared in evolutionary history and thus help to understand when, where and why the human lineage evolved. South African Middle Stone Age (MSA) sites have figured prominently in this work, revolutionizing knowledge of modern human origins by pushing back and enriching knowledge of the timing of key features science considers definitive of humans. Modern dating techniques and their application to archaeological sites provide the basis for determining when key events in early human history occurred. These techniques use complex models that produce age estimates and not absolute dates. In the past, different laboratories have used different models that may result in different ages for the same geologic unit. This has created a dating controversy that reduces confidence in the timing of key events in early human prehistory. There is general agreement that the best way of producing robust age estimates is to use several independent dating techniques. Recently, the research team identified volcanic ash in a rock shelter occupied by early humans at Pinnacle Point, South Africa, and the best fit of the chemistry of this ash is to the 75,000 year old eruption of the Toba volcano in Indonesia. This discovery provides an independent dating tool that can be used along with traditional dating methods to resolve the dating controversy and tie the record of human origins preserved at Pinnacle Point and other areas of southern Africa to the global record of modern human origins. Drs. Smith and Marean and their research team will collect and process samples from four archaeological sites in southern Africa to identify and determine the distribution of ash from the Toba eruption. This work will, for the first time, tie early human history recorded at each of these sites to a single dating model and remove any debate about the timing of key events in early human development. Correlation of volcanic ash to source volcanoes will be done using the chemistry of the ash. The ash is in the form of very small (micron sized) glass grains known as shards. These grains are analyzed by instruments that focus a small-diameter electron or laser beam on the shard to determine their chemical makeup. The chemistry is then compared to a database of known chemistry to identify the source and age of the ash. This project will not only provide a new independent dating tool for archaeological sites, but also help train students and early career scientists in the techniques of archaeology and geology.