Tetsuro Matsuzawa1,2,3. 1. Kyoto University Institute for Advanced Study, Kyoto, Japan. matsuzawa.tetsuro.8w@kyoto-u.ac.jp. 2. Primate Research Institute, Kyoto University, Inuyama, Japan. matsuzawa.tetsuro.8w@kyoto-u.ac.jp. 3. Japan Monkey Centre, Inuyama, Japan. matsuzawa.tetsuro.8w@kyoto-u.ac.jp.