Luminescence Sediment Dating of Pleistocene Hominin and Tool Sites at Atapuerca, Spain

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Supported by the National Science Foundation, Dr. Glenn Berger will conduct 2 weeks of field work in northern Spain with Spanish colleagues at the UNESCO World Heritage Archeological Site of Atapuerca, near Burgos. For the last 1-million-year period, this is one of the world's most important site for fossils, tools and faunal finds related to the presence of ancestors to modern humans, yet much of the timing for the deposition of the various finds at the 3-4 related sites at Atapuerca is uncertain. Understanding when human ancestors arrived in Europe and how they evolved thereafter requires knowing the ages of the fossil and stone-tool finds. Absent evidence for use of fire and pottery (none yet found at Atapuerca before the last 50,000 yrs), such stone tools are the main preserved representations of the cultural behaviors of human ancestors of such antiquity. Furthering an international collaboration begun in 1997, Berger and Spanish colleagues will collect sediment samples throughout 3 of the cave sites (Gran Dolina, Galería, Elefante) at Atapuerca. In his laboratory in Reno, Nevada, Berger will apply several variations of a sediment-dating technique that measures luminescence to be stimulated artificially from unheated mineral grains. His 2008 published report (Journal of Human Evolution) demonstrated for the first time that luminescence techniques could date sediments from 2 (Gran Dolina and Galería) of the Atapuerca cave deposits, back to about 1 million years. The current project not only will attempt to provide a better age for the old skull at Gran Dolina, but will provide the first numeric ages for stone tools from a relatively new cave site (Elefante), and more precise and accurate ages for tools from the 2 other mentioned cave sites. In a broader context, these ages will place the development of the tool styles into a numeric time series and thus permit relating these developments in the technologies of human ancestors to those from other sites around the world. Knowledge of the sequence of development of tool styles in different areas of the world is an important key to understanding human evolution. As well, such numeric time scales are essential for relating the migration and evolution of human ancestors in Europe to their likely connections to Asian-African forebears. Numeric time scales are critical for the search for causes of and effects on the evolutionary changes in regional fossil plants and animals, such as climatic changes. This project also will develop a cross-comparison of luminescence ages with the few available numeric ages from two other dating techniques (ESR and cosmogenic-nuclide dating). Such comparisons are rare in archeological studies beyond the age range of radiocarbon dating (about 35,000 yrs) in areas lacking volcanic deposits (such as much of Europe). Moreover, this project will permit undergraduate students in Reno to participate in cutting-edge laboratory research.