1. Science of Motion, Friedrich-Schiller-University, 07749 Jena, Germany
2. Institute of Zoology and Evolutionary Research, Friedrich-Schiller University, 07743 Jena, Germany
3. Primate Research Institute, Kyoto University, Inuyama, Aichi 484-8506, Japan
4. Department of Mechanical Engineering, Keio University, 3-14-1 Hiyoshi, Kohoku-ku, Yokohama 223-8522, Japan
5. Department of Biological Science, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan