Analyzing dozens of spontaneous performances by a captive male chimpanzee named Ayumu, researchers said the animal’s steady rhythm and expressive “playful face” suggest how early humans translated vocal emotion into musical instrument sounds.
The chimpanzee Ayumu spontaneously produced long multi-element musical displays by drumming, dragging, and throwing separated objects. Analysis of transitions and rhythms revealed non-random sequences, partially resembling a pant-foot structure, primarily isochronous timing, and a more stable tempo using tools than using the body. The accompanying playful facial expressions and tooth-baring quiet expressions suggest high arousal and positive emotions, supporting the idea that emotional vocal expressions can be externalized through instrumental sounds. Image provided by: Hattori others., doi: 10.1111/nyas.70239.
In February 2023, Ayumu, a 26-year-old male chimpanzee at the Center for Research on the Origins of Human Behavior and Evolution at Kyoto University, performed a spontaneous musical performance for researchers.
He removed floorboards from the walkways and used them for drums, creating complex, structured sounds similar to vocal expressions.
Dr. Yuko Hattori of Kyoto University and colleagues say, “Ayumu’s drumming is not new.”
“Chimpanzees are well known for playing musical instruments, and are particularly good at drumming.”
“However, in this case, the combination of Ayumu’s drumming and vocalizations exhibited multiple rhythmic elements, making it an entirely new case.”
From February 2023 to March 2025, the authors recorded a total of 89 spontaneous performances by Ayumu.
The recording shows him ripping floorboards from a walkway and using them as tools to make music.
“It was very interesting to see how chimpanzees use tools to make various sounds and express vocal expressions,” said Dr. Hattori.
The researchers used Ayumu’s performance to test whether vocal expressions could be transferred to instrumental sounds.
They first assessed his actions, breaking it down into elements such as hitting, dragging, and throwing.
We then used transition analysis to assess the connections between these elements and determine which transitions occurred by chance and which occurred on purpose.
Finally, they analyzed the intervals between strikes and compared the rhythmic stability of tool use to the stability of hand and foot drumming.
Analysis revealed that the order of the sounds produced by the tool was not random, and the intervals between blows were isochronous, maintaining a constant tempo, similar to a metronome.
In fact, using tools will give you a more consistent rhythm than using just your hands and feet.
The researchers also observed facial expressions, such as the “play face,” which is usually associated with play and indicates positive emotions.
Such expressions are not typically reported in audio displays, suggesting that emotional signals once conveyed vocally may have been externalized and evolved into tool-based sounds.
“Ayumu’s performance demonstrates that non-human primates also have the ability to externalize voice-like expressions using musical instruments,” the authors said.
“Next, we are interested in analyzing the reactions of other chimpanzees and the impact that Ayumu’s display has within his social group.”
This study Annual Report of the New York Academy of Sciences.
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Yuko Hattori others. 2026. Combination instrument sound production in captive chimpanzees: Evolution of vocal externalization. Annual Report of the New York Academy of Sciences 1557 (1): e70239;doi: 10.1111/nyas.70239
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