Toshisada Nishida (3 March, 1941 – 7 June, 2011) was a Japanese primatologist who established one of the first long term chimpanzee field research sites. He was the first to discover that chimpanzees, instead of forming nuclear family-like arrangements, live a communal life with territorial boundaries. His discoveries of the medicinal use of plants by wild chimpanzees helped form the basis of the field of zoopharmacognosy. Nishida was a full professor of Zoology at Kyoto University, the President of the Primate Society of Japan, the President of the International Primatological Society, and the Editor-in-Chief of the journal Primates. In 2008, he was a recipient of the Leakey Prize for his accomplishments in human evolutionary science. Scientific career Early career As a graduate student, Toshisada Nishida studied primatology at Kyoto University under Junichiro Itani, a successor of Japanese primatologist Kinji Imanishi. Nishida studied Japanese macaques with Imanishi from 1963-1965 before travelling to Tanzania to study chimpanzees. Chimpanzee research Despite being more genetically distant from humans than chimpanzees, in the 1960s baboons were considered the best model of human evolution as they had descended from the trees to become savanna-dwellers like early humans did. However, baboons did not possess many of the characteristics deemed important for human evolution, such as tool technology, cooperative hunting, food sharing, territoriality, cultural traditions, and certain cognitive capacities, such as planning and theory-of-mind. Chimpanzees, however, show all characteristics. Early primatologists had observed chimpanzees traveling through trees, eating fruits at their leisure, but rarely noted anything of interest in their behaviour. In the 1960s, there were only two field sites studying chimpanzee behaviour: one led by Jane Goodall in the Gombe Stream, and another located in the foothills of the Mahale Mountains at Lake Tanganyika, which was staffed by Japanese scientists and led by Nishida. Nishida's team planted sugarcane to attract the chimpanzees, who began to consistently visit the site after only six months. Based on his field observations, Nishida defended his dissertation at Kyoto University in 1968. Discoveries regarding chimpanzees During Nishida's first visit to Mahale, he observed chimpanzees living in communities with territorial boundaries, noting the existence of hostility between neighbouring groups. As chimpanzees are often encountered alone or in small groups in the forest, and due to the difficulty of determining community relations between chimpanzees, this challenged the existing scientific belief that chimpanzees lived in nuclear family-like groups. At the Mahale site, scientists followed Kinji