Kanzi, a male bonobo with advanced language aptitude, has died at the age of 44 according to a statement by the Ape Initiative, the conservation and research center in Des Moines, Iowa, where he had lived since 2004.
As an infant, Kanzi, who was born at the Emory National Primate Research Center in Atlanta, Georgia, accompanied his adoptive mother Matata to language lessons. But while Matata was not interested in learning from her human caretakers, Kanzi surprised them by quickly learning the lexigrams, or symbols that map to words, that the researchers were trying to teach his mother, in much the same way human children learn language by listening to their parents talking.
Primatologists have used lexigrams since the 1970s to understand how chimpanzees and bonobos think and communicate. Using a special lexigram keyboard, the great apes are encouraged to communicate with their caretakers by pressing different buttons or pointing to pictures.
Researchers taught Kanzi more than 300 lexigrams, and Kanzi combined them to create new meanings, an important aspect of symbolic thinking — something which experts previously assumed only humans were capable of.
But Kanzi was also able to understand and respond to requests in spoken English. In a study undertaken when Kanzi was 8 years old, he and a 2-year-old human child were given 660 spoken instructions. Kanzi outperformed the child, suggesting his linguistic ability was at least as good as a human toddler’s.
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In another study, Kanzi learned some American Sign Language (ASL) simply by watching videos of Koko the gorilla, who had previously been taught to use ASL. And when separated by a wall from his sister, Panbanisha, Kanzi vocalized a sound for ‘yogurt’ that Panbanisha understood.
Although Kanzi showed one-of-a-kind linguistic abilities for an ape, he didn’t speak in the same way humans do. Researchers think this is related to the anatomical differences between chimpanzee and human vocal tracts. However, a 2024 study published in Scientific Reports suggests that chimpanzee vocalization abilities may have been underestimated, as these apes can produce novel sounds and have the brain capacity necessary for speech.
Beyond his language skills, Kanzi showed off his ability to make and use stone tools, earning him the epithet “bonobo genius.” He was then taught to build a fire and cook food, demonstrating his ability to learn behaviors key to human evolution.
Later in life, Kanzi was even taught to play video games. He seemed to understand how to beat the arcade game Pac-Man and defeated the final boss of Minecraft.
On March 18, staff at the Ape Initiative found Kanzi unresponsive. He was being treated for heart disease, according to the statement, but necropsy results clarifying his cause of death are pending.
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