1. School of Archaeology and Museology, Peking University, Beijing 100871, China.
2. Department of Archaeology, Boston University, Boston, MA 02215, USA.
3. Eberhard Karls University Tübingen, The Role of Culture in Early Expansions of Humans, Rümelinstraße 23, D-72070 Tübingen, Germany.
4. Department of Anthropology, Harvard University, Cambridge, MA 02318, USA.