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

University Of Washington, Seattle WA

Investigators

Abstract

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.