Researchers who have analyzed dozens of spontaneous performances of a captive male chimpanzee called Ayumu say the animal’s steady rhythms and ‘facial play’ suggest how ancient humans might have turned vocal sensations into musical sounds.
Ayumu made his own long multi-piece instruments by drumming, pulling and throwing. Analysis of the transitions and rhythms revealed a random sequence that resembles a pant-hoot structure, mostly isochronous timing, and a steady tempo when using the instruments more than the body. Expressions accompanied by a playful face and quiet clenched teeth suggest arousal and positive influence, which supports the idea that an emotional voice can be expressed externally through the sound of instruments. Image credit: Hattori and al., doi: 10.1111/nyas.70239.
In February 2023, Ayumu – a 26-year-old chimpanzee at Kyoto University’s Center for Evolutionary Origins of Human Behavior – surprised researchers with spontaneous music.
He would remove floorboards from the footpath and use them to beat the drum, making complex, structured sounds like words.
“Ayumu’s drumming is nothing new,” said Dr. Yuko Hattori and her colleagues at Kyoto University.
“Chimpanzees are well known for playing their instruments, and they are especially good at playing drums.”
“But on this occasion, Ayumu’s combination of drumming and vocals – showing many layers of rhythm – was a whole new story.”
Between February 2023 and March 2025, the authors recorded a total of 89 Ayumu performances.
The recordings recorded how he removed the floorboards from the sidewalk and used them as instruments to make music.
Dr. Hattori said: “It was amazing to see how the chimpanzees used tools to produce different sounds while making vocal sounds.
Using Ayumu’s simulations, the researchers tested whether a voice’s expression can be transformed into an instrument’s sound.
They first analyzed his behavior and divided it into categories such as hitting, pulling and throwing.
They then assessed the relationships between these components through change analysis, to determine which changes were accidental and which were intentional.
Finally, they analyzed the intervals between beats and compared the rhythmic stability of tool use to that of hand or foot drumming.
The analysis revealed that the sequence of sounds produced by the instruments was not random, and that the intervals between beats were isochronous – maintaining a constant tempo, like a metronome.
In fact, the use of tools produced a more consistent rhythm than just the hands or feet.
Scientists have also observed a facial expression such as the ‘play face,’ which is often associated with play, which shows positive emotions.
Such utterances are rarely reported in vocal transmissions, suggesting that emotional signals once transmitted verbally may be externalized and made into instrumental sounds.
“Ayumu’s performances prove that non-human primates also have the ability to produce vocal-like sounds through instruments,” the authors said.
Next, we are interested in examining the feelings of other chimpanzees, and the impact that Ayumu’s display has on his social group.
The study was published in Annals of the New York Academy of Sciences.
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Yuko Hattori and al. 2026. Combinatorial Instrumental Sound Production in a Captive Chimpanzee: Evolution of Vocal Externalization. Annals of the New York Academy of Sciences 1557 (1): e70239; doi: 10.1111/nyas.70239
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