Monday, May 12, 2025

Chimpanzees have rhythm, chimpanzee communities have their own beat

Amazing stuff! Let the music play! Play it one more time! 😊

"Deep in the African rainforest, chimps aren’t just making noise—they’re drumming to the beat of their own communities. Two new studies reveal that chimpanzees drum with distinct, consistent rhythms that differ between groups, hinting at the roots of human musicality.

In one study, a team analyzed 370 drumming bouts from wild chimps from two subspecies over 25 years. The researchers found that western chimpanzees (Pan troglodytes verus) tend to drum in even beats, “like the ticking of a clock,” ... However, eastern chimps (P.t. schweinfurthii ) use a more varied rhythm, alternating short and long pauses. These patterns, paired with pant-hoots and body swaying suggesting deep-rooted social or cultural influences.

Meanwhile, another study ... a rare twist: Some western chimps drum with stones. In Guinea-Bissau, researchers analyzed chimps throwing rocks at resonant tree trunks—often at trees where stones were already stockpiled—suggesting a socially learned, possibly cultural behavior.

The fact that chimps not only drum rhythmically but also vary how they do it raises questions about the evolutionary origins of music. It’s not just random noise—it’s a structured communication signal."

From the highlights and abstract (1):
"Highlights
• Chimpanzees show non-random timing and isochrony in drumming
• Chimpanzee drumming shows key elements of human musical rhythm
• Chimpanzee drumming shows regional (subspecies) variation across diverse ecologies
Eastern and western chimpanzees have different drumming rhythms

Summary
Rhythmic percussion is present across human cultures and has been proposed as one of the earliest evolved forms of musical expression.
Key features of human rhythmic percussion include individual and regional variation, as well as structural features widespread across musical cultures, such as the use of non-random timing and isochrony (i.e., evenly spaced note onsets). Comparative studies of drumming in our ape relatives contribute to understanding the evolutionary origins of human rhythmic percussion. In this context, large, diverse datasets allow testing for species-level universals and regional variation. Chimpanzees and bonobos, like humans, drum on instrumental substrates. 
Wild chimpanzees drum on resonant tree buttresses, showing individual variation during traveling and resting contexts, and often integrate drumming into their long-distance pant-hoot vocalizations. But whether wild chimpanzee drumming shows structural musical features and regional variation in rhythm or in its integration within pant-hoots remains unknown.
We show that wild chimpanzees drum with non-random timing and isochrony, providing evidence that rhythmic drumming on instrumental substrates may have been present in our last common ancestor. Furthermore, we found subspecies-level regional rhythmic variation, showing that western chimpanzees drum isochronously, while eastern chimpanzees drum by alternating shorter and longer inter-hit intervals. Western chimpanzees also produce more drumming hits, drum at a faster tempo, and integrate drumming earlier in the pant-hoot vocalization, typically during the rhythmic build-up phase. Chimpanzee buttress drumming shows both species-level structural features of human musicality and stable subspecies regional differences across diverse ecologies."

From the abstract (2):
"Chimpanzees (Pan troglodytes) communicate in complex ways, including sounds produced by hand and foot drumming on trees, often combined with loud vocalizations. Recently, a puzzling stone throwing behaviour at trees was observed, resulting in stone piles at tree buttresses.
It is a rare case of tool used for communication in animals and suggested to function like buttress drumming in long-distance communication and male displays. We tested this hypothesis by determining the behavioural dynamics in comparison to hand and foot tree buttress drumming in Western chimpanzees in Boé, Guinea Bissau. Using camera traps, we show that in 78% of cases, stones were picked up at trees, not leading to further stone accumulation beyond the already existing stone piles.
Stone-assisted and hand and foot drumming occurred separately or were combined in similar behavioural contexts in apparent long-distance communication and highly aroused behavioural contexts. 
Yet, immediately before stone drumming, chimpanzees swayed less and pant-hooted more while afterwards pant-hooting less compared to the other contexts, suggesting a separate motivation and/or function for stone-assisted drumming. It suggests this unique stone-based activity has its own signal value, separate from hand/foot buttress drumming and, considering the spatial variation, might be culturally transmitted."

ScienceAdviser

Chimpanzee drumming may give clues to the roots of rhythm "Behavior is more complex than scientists realized, could reveal origins of musicality"





Figure 1 Examples of chimpanzee subspecies’ drumming


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