Kyoto, Japan - Ai, a "genius" chimpanzee who could recognize more than 100 Chinese characters and the English alphabet, has died aged 49, Japanese researchers said.

Ai, which means love in Japanese, took part in studies on perception, learning, and memory that advanced our understanding of primate intelligence, the Center for the Evolutionary Origins of Human Behavior at Kyoto University said in a statement.

She died Friday from multiple organ failure and ailments related to old age, the school said.

Aside from mastering Chinese characters and the alphabet, Ai could also identify the Arabic numerals from zero to nine and 11 colors, primatologist Tetsuro Matsuzawa said in 2014.

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In one study, Ai was presented with a computer screen displaying the Chinese character for pink, along with a pink square and an alternative purple square. The chimpanzee correctly chose the pink square, Matsuzawa said.

When shown an apple, Ai picked out a rectangle, a circle, and a dot on the computer screen to draw a "virtual apple," he said.

Her high ability made her the subject of a number of scholarly papers and media programs, including studies published in the journal Nature, and earned her the nickname "genius" in popular media.

The chimpanzee from west Africa arrived at the university in 1977, and in 2000, gave birth to a son Ayumu, whose abilities drew attention to studies of parent-child knowledge transfer, Japan's Kyodo News said.

Ai's studies helped to establish "an experimental framework for understanding the chimpanzee mind, providing a crucial foundation for considering the evolution of the human mind," the Center said.

"Ai was highly curious and actively participated in these studies, revealing various aspects of the chimpanzee mind for the first time."