Mahale Mountains Parc national

While Jane Goodall's work at Gombe was rewriting western science's understanding of chimpanzees in the early 1960s, on the same lake é 160 kilometres to the south é a parallel revolution was quietly unfolding. In 1961, the Japanese primatologist Kinji Imanishi launched the Kyoto University Africa Primatological Expedition, sending his students and colleagues to study wild chimpanzees on the shores of Lake Tanganyika. In 1965, a young graduate student named Toshisada Nishida a établi un camp de recherche à Kasoje, dans la plaine boisée au pied de ce qui allait devenir le parc national des monts Mahale. Il restera connecté à cette forêt, à ces montagnes et à ces chimpanzés pour le reste de sa vie.

La méthode d'habituation de Nishida était innovante et soigneusement conçue. Plutôt que d'utiliser une station d'alimentation fixe, il a développé "mobile provisioning" é distributing food at random locations, then announcing the researchers' presence by imitating the chimpanzees' own hooting calls. The chimpanzees approached and ate; the researchers observed. Because no fixed station was established, the chimpanzees' natural ranging and social patterns remained intact é the data collected was not distorted by the artificial concentration of animals at a single point. Over years of patient daily contact, first the K-group and then the M-group accepted the Japanese researchers as a harmless presence in their world.

Les découvertes qui ont suivi Mahale ont à la fois mis en parallèle et contredit les découvertes de Gombe d'une manière qui a fondamentalement fait progresser la science du comportement des chimpanzés. Nishida et ses collègues ont documenté chimpanzees consuming Aspilia leaves é leaves with no nutritional value, swallowed whole without chewing é and correctly proposed that the behaviour was medicinal, the chimpanzees self-treating intestinal parasites with the plant's bioactive compounds. This was the first documented evidence of medicinal plant use by any non-human animal. The Mahale researchers also documented handclasp grooming é a behaviour in which two individuals simultaneously groom each other with one arm raised and hands clasped overhead é which had never been observed at Gombe and was the first evidence that different chimpanzee populations had genuinely different cultural practices, passed between generations by social learning rather than genetics.

When Nishida invited the Gombe researchers William McGrew and Caroline Tutin to Mahale in 1975, the shock of finding behaviours at Mahale that simply did not exist at Gombe é and vice versa é was the moment that the concept of chimpanzee culture was born as a serious scientific proposition. In 1985, after two decades of advocacy, Nishida successfully lobbied the Tanzanian government é with financial support from Japan's International Cooperation Agency é to gazette Mahale as a national park. It was the first national park in Tanzania designated specifically for foot-based access. In 2008, Nishida and Jane Goodall were jointly awarded the Leakey Prize é the field's highest honour é for their parallel contributions to human evolutionary science. Nishida made his last visit to Mahale in the summer of 2009 and passed away in 2011, leaving a 60-year research legacy that continues today under the Kyoto University research programme that he built.