*Osamu Toyoshima¹, Ryo Matsumoto², Jun Kunimatsu³, Masayuki Matsumoto^3,4 (1. Ph. D. Program in Humanics, University of Tsukuba, Japan, 2. Ph. D. Program in Human Biology, University of Tsukuba, Japan, 3. Institute of Medicine, University of Tsukuba, Japan, 4. Center for the Evolutionary Origins of Human Behavior, Kyoto University, Japan)