At Kumamoto Sanctuary, we have received bonobos from US zoos and initiated a new scientific project to study them. Currently Kumamoto Sanctuary is the only place in Japan housing bonobos, and it is also home to the largest number of chimpanzees in the country. Chimpanzees and bonobos are the closest living relatives of humans, and can thus be called our evolutionary neighbors. By conducting a comparative study of chimpanzees and bonobos, we seek to uncover the evolutionary origins of the human mind. We are also engaged in fieldwork studies of their wild counterparts in Africa. Through these “two-by-two comparisons,” that is, chimpanzees vs. bonobos and wild vs. captivity, we aim to gain true knowledge about human nature.