Researchers at Kyoto University have documented a captive chimpanzee named Ayumu exhibiting remarkably structured drumming behavior, providing new insights into how early humans may have transitioned from vocal emotional expression to instrumental sound. Over two years, from February 2023 to March 2025, scientists observed Ayumu performing 89 spontaneous drumming sessions using tools – specifically, floorboards removed from a walkway.
The Novelty of Ayumu’s Performances
While chimpanzees are known for using tools to create sounds, Ayumu’s performances stood out due to the combination of rhythmic complexity, deliberate tool use, and accompanying vocalizations. The researchers, led by Dr. Yuko Hattori, determined that the sounds weren’t random. Instead, Ayumu maintained a steady tempo, even more consistently than when drumming with hands or feet.
How the Study Was Conducted
The team systematically broke down Ayumu’s actions – striking, dragging, and throwing – and used transition analysis to differentiate deliberate sequences from chance occurrences. They found that intervals between strikes were isochronous, meaning they maintained a constant rhythm like a metronome. This suggests a cognitive ability to structure sound production beyond simple accidental noise.
Emotional Expression and the Evolution of Music
Crucially, Ayumu displayed a “play face” – a facial expression associated with positive emotions – during his performances. This is significant because such expressions are rarely observed in vocal displays. The team proposes that this suggests emotional signals once conveyed through vocalizations may have been externalized into tool-based sounds.
“Ayumu’s performances prove that non-human primates also possess the ability to externalize vocal-like expressions with instruments,” the authors concluded.
Future Research and Social Implications
The study, published in the Annals of the New York Academy of Sciences, raises further questions about how these displays impact chimpanzee social dynamics. Researchers now plan to analyze the reactions of other chimpanzees to Ayumu’s drumming, seeking to understand its role within their group.
This research suggests that the roots of musical expression may be deeper than previously thought, potentially predating complex vocal development in early hominids. It highlights how tool use could have played a critical role in the evolution of rhythm and emotional communication.
