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

内华达大学拉斯维加斯分校的尤金·史密斯博士和亚利桑那州立大学的柯蒂斯·马雷恩博士将与一个国际科学家团队一起，应用一种新的测年方法来确定一组独特的人类特征首次出现在进化史上的时间，从而帮助理解人类血统何时、何地和为什么进化。南非中石器时代(MSA)遗址在这项工作中发挥了重要作用，通过推迟和丰富科学认为对人类具有决定性意义的关键特征的时间安排，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的时间提供了基础。这些技术使用复杂的模型，产生年龄估计，而不是绝对日期。在过去，不同的实验室使用不同的模型，这可能会导致同一地质单位的不同年龄。这引发了一场约会争议，降低了人们对早期人类史前关键事件的时间安排的信心。人们普遍认为，做出可靠的年龄估计的最好方法是使用几种独立的测年技术。最近，研究小组在南非顶峰点一个早期人类占据的岩石掩体中发现了火山灰，这些火山灰的化学成分最符合印度尼西亚7.5万年前的托巴火山喷发。这一发现提供了一种独立的测年工具，可以与传统的测年方法一起使用，以解决测年争议，并将尖峰点和南部非洲其他地区保存的人类起源记录与现代人类起源的全球记录联系起来。史密斯和马雷恩博士以及他们的研究团队将从南部非洲的四个考古遗址收集和处理样本，以识别和确定托巴火山喷发产生的火山灰的分布。这项工作将首次将每个地点记录的早期人类历史与单一的测年模型联系起来，并消除关于人类早期发育中关键事件发生时间的任何争论。火山灰与源火山的关联将使用火山灰的化学成分来完成。火山灰是被称为碎片的非常小的(微米大小)玻璃颗粒。这些颗粒由仪器分析，这些仪器将小直径的电子束或激光束聚焦在碎片上，以确定它们的化学组成。然后，将该化学物质与已知化学物质的数据库进行比较，以确定火山灰的来源和年龄。该项目不仅将为考古遗址提供一个新的独立测年工具，还将帮助培训学生和早期职业科学家的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.