The Kyoto University Centre for the Evolutionary Origins of Human Behaviour – formerly the Primate Research Institute – in Inuyama, Aichi Prefecture said Ai was born in western Africa in 1976 and arrived at the institute in 1977. She began language-learning experiments with human symbols, including computers, at about 18 months old.
Ai died last Friday under the care of institute staff, the centre said.
Over decades of study, Ai became widely known for her strong literacy and numerical recognition skills. She learnt to identify visual symbols that included about 100 items – Japanese kanji characters, letters of the alphabet, Arabic numerals, and lexigrams (symbols representing words or concepts) – and could match them meaningfully to objects, colours and numbers.
In one well-publicised demonstration in the early 1980s, Ai was shown a green image and correctly pointed to the kanji character for “green”. That work was featured in the British journal Nature in 1985 as an early demonstration of chimpanzee cognitive abilities previously thought to be uniquely human.
Ai’s intelligence also showed in everyday problem solving. In 1989 she escaped her enclosure with another chimpanzee, prompting researchers to learn that she had worked the padlock using a key.
Her legacy continued through her son Ayumu, born in 2000, who became a focal point of research on parent-to-child transfer of knowledge and memory skills.
In studies involving computers, young chimps including Ayumu were able to recall sequences of numerals on screens with extraordinary accuracy – even when these images appeared for a split second – outperforming adult human participants in short-term memory tasks.
The decades of work with Ai and her offspring were led by primatologist Tetsuro Matsuzawa of Kyoto University’s institute, whose “Ai Project” has helped scientists explore how chimpanzees perceive symbols and solve problems, offering further insights into the evolutionary roots of human cognition.
Ai’s contributions helped cement her status not just as a subject of academic research, but as one of the most scientifically influential individual chimpanzees in modern primatology.