1. Department of Anthropology, Western Washington University, Bellingham, WA 98225
2. Department of Environmental Sciences, Western Washington University, Bellingham, WA 98225
3. Berkeley Geochronology Center, Berkeley, CA, 94709
4. Human Evolution Research Center, University of California, Berkeley, CA 94720
5. Centro Nacional de Investigación sobre la Evolución Humana, Burgos, Spain 09002
6. Department of Integrative Biology, University of California, Berkeley, CA 94720