Acquisition of a New Generation Mass Spectrometer for 40Ar/39Ar Dating in Human Origins Research

Berkeley Geochronology Center, Berkeley CA

Investigators

Abstract

This award permits of at the Berkeley Geochronology Center (BGC) to purchase a new mass spectrometer for 40Ar/39Ar dating in order to address the ongoing challenge of establishing the timescale of human evolution. Understanding the timing and tempo of human and hominid evolution requires the accurate dating of fossils and artifacts. Lacking DNA from fossil species, some of the most useful lines of evidence for inferring phylogenetic relationships come from temporal relations between taxa, via the simple ordering of fossils and artifacts in a calibrated time sequence. It is increasingly apparent that improved understanding of evolutionary causality in terms of environmental pressures requires the ability to correlate evolutionary processes such as speciation, radiation and extinction with environmental change. In the face of mounting evidence for large climate fluctuations on timescales as short as 10,000 years, for example, it becomes critical to be able to date evolutionary events with comparable resolution. The BGC laboratory as part of it's long history has applied the K-Ar dating technique, and it's more precise and accurate variant the 40Ar/39Ar dating method, to archaeometric problems for the past 50 years. For the past 20 years the laboratory has been using mass spectrometers (machines designed to measure the isotopes of vanishingly small quantities of argon gas) of a particular genre (from the now non-existent Mass Analyzer Products of Manchester, England). However, in the past three years or so, mass spectrometers suitable for this purpose have suddenly made a quantum leap in their ability to measure gasses with greater speed and accuracy. Funding for a modern mass spectrometer of this class will permit BGC to bring this new powerful tool to bear, yielding improvements in the accuracy and precision of dating of fossil hominids and their archeological records, as well as the chronology of the paleoenvironmental context within which they must be understood. In summary, this award permits the BGC to exploit recent technical developments and emplace new dating capabilities which will significantly enhance the scope of materials that can be dated, the precision and accuracy of dating, and the analytical throughput. This proposal supports the purchase of a fundamentally new type of mass spectrometer, which will be the cornerstone of a fully automated system capable of delivering more and better data than any previous system of its kind applied to archaeometric problems. The BGC has an extensive record of development and implementation of such facilities, and a longstanding commitment to their application in support of paleoanthropological and archeological research. BGC's commitment of ancillary equipment, software development, and technical support ensures that NSF funding is highly leveraged.