1. Department of Mechanical Engineering, Faculty of Science and Technology; Keio University; Yokohama 223-8522 Japan
2. Department of Biological Sciences, Graduate School of Science; University of Tokyo; Tokyo 113-0033 Japan
3. Department of Precision Engineering, Graduate School of Engineering; University of Tokyo; Tokyo 113-8656 Japan
4. Anthropological Institute, University of Zurich; Zürich CH- 8057 Switzerland
5. Paleoanthropology Group, Department of Paleobiology; Museo Nacional De Ciencias Naturales; Madrid 28006 Spain
6. Department of Earth Sciences; Natural History Museum; London Sw7 5BD UK