When John Mitani first walked into Uganda's Kibale national park in 1995, he was struck by how loud the forest was. Fruit trees towered 40 metres overhead, and black shapes crashed through the branches, calling to each other with a volume that seemed almost impossible. Mitani, a primatologist who had just finished fieldwork in Tanzania's Mahale mountains, had heard rumours about an unusually large group of chimpanzees living in Kibale's Ngogo region. Within days, he understood why people were talking.

At Mahale, researchers had documented around 100 chimpanzees, a number that was already considered remarkable for a single community. In Ngogo, Mitani and his colleagues eventually counted nearly 200 chimps coexisting in the same stretch of forest, a discovery that unsettled assumptions about how large a peaceful chimp troop could grow. Later that year, Mitani and Yale primatologist David Watts used a $500,000 grant from the US National Science Foundation to establish the Ngogo Chimpanzee Project. Three decades later, it remains one of only twelve long-term chimpanzee studies conducted anywhere in the world under natural conditions.

Trust did not come quickly. The chimps fled whenever researchers approached, forcing Mitani's team to track them across hills and valleys for months without a single calm encounter. The breakthrough came from a 25-year-old male identifiable by a cleft palate, later named Hare. While Mitani was watching chimps feed in a fig tree during his second year, Hare climbed down and, instead of bolting as expected, walked slowly toward another fruit tree, allowing Mitani to follow at a distance for the first time.