Luminescence dating of Late Pleistocene/Early Holocene archaeological sites in Brazil

自19世纪以来，考古学家一直在争论关于人类何时首次殖民新大陆的问题。直到最近，争论一直集中在北美的证据上，因为假定的入口点是通过北美，而被广泛接受的最早的石器传统，克洛维斯，仅限于北美。越来越多的人接受智利南部蒙特维德遗址的克洛维斯之前的日期，这将注意力集中在南美的证据上。南美的记录作为一个整体表明，早期的技术和适应与克洛维斯截然不同，不太可能是它的后代。这是一个令人信服的论点，证明南美洲的占领至少与克洛维斯同时代，如果不是早于克洛维斯的话，但对这一证据的记录比北美的要差得多。尤其有问题的是这一早期证据的年代。在国家科学基金会的资助下，华盛顿大学的詹姆斯·费瑟斯博士将在未来两年内进行一项发光测年计划，目标是巴西中部的晚更新世/早全新世遗址。这项工作的大部分是与圣保罗大学的考古学家和体质人类学家合作进行的，他们一直在对里约热内卢以北的米纳斯吉拉斯拉戈亚圣诞老人地区的早期遗址进行系统研究。这是一个喀斯特地区，以石灰岩避难所而闻名，那里有100多具人类骨骼，据信可以追溯到早期。就像华盛顿州著名的肯威克人一样，这些骨骼在解剖学上与现代美洲原住民不同，可能表明他们早期从南亚迁徙到新大陆。发光测年建立在固体物理学的基础上，能够测定沉积物最后一次暴露在光下的时间，通常是在沉积的时候。通过发光测定单个颗粒的年龄的能力使该方法能够识别混合或受干扰的沉积物，并可能确定其日期。在早期遗址，地层完整性往往是一个问题。这项工作将为华盛顿大学和圣保罗大学的学生提供培训。关于人们第一次来到新大陆的方式和时间，有许多相互竞争的论点。这项研究的长期目标是从南美提供一些确凿的证据，以便对这些不同的论点进行评估。这项工作的成果将在国际期刊上发表，并分发给大众报刊。

The question about when humans first colonized the New World has been debated by archaeologists since the 19th century. Until very recently, the argument has centered on North American evidence, since the presumed entry point is through North America and the earliest lithic tradition that is widely accepted, Clovis, is confined to North America. The growing acceptance of pre-Clovis dates for the Monte Verde site in southern Chile has focused attention on the South American evidence. The South American record as a whole suggests an early technology and adaptation quite distinct from Clovis and not likely descendent from it. This is a compelling argument for occupation in South America at least contemporary with if not earlier than Clovis, but documentation of this evidence is much poorer than that for North America. Particularly problematic is the dating of this early evidence. With funding support from the National Science Foundation, Dr. James Feathers of the University of Washington will over the next two years be conducting a luminescence dating program targeting late Pleistocene/early Holocene sites in central Brazil. Much of this work is in collaboration with archaeologists and physical anthropologists from the University of Sao Paulo, who have been conducting a systematic study of early sites in the Lagoa Santa region of Minas Gerais, north of Rio de Janeiro. This is a karstic region renowned for limestone rockshelters containing more than 100 human skeletons believed to date to this early period. Like the famous Kenewick Man from Washington state, these skeletons differ anatomically from modern native Americans and may indicate an early migration to the New World from south Asia. Luminescence dating is founded in solid state physics and is able to date sediments to their last exposure to light, usually when they were deposited. The ability to date single grains by luminescence allows the method to identify and potentially date mixed or disturbed sediments. Stratigraphic integrity is often a problem at early sites. The work will provide training for students from both the University of Washington and the University of Sao Paulo. There are many competing arguments for how and when people first arrived in the New World. The long term goal of this research is to provide some solid evidence from South America to allow evaluations of these various arguments. Results from this work will be published in international journals and disseminated to the popular press as well.