Plate Nº 72 · recorded November 10, 2026
Biology & EvolutionReported finding
Chimpanzee calls show first evidence of learned conventions
A 2026 study of 91 chimpanzees found evidence that communities can develop shared rules for using a raspberry call, with one adult's arrival shifting a group's pattern over time.
By Elena Vasquez4 min read869 words
In brief
- A 2026 PNAS study examined 91 chimpanzees ranging from birth to 55 years old.
- Researchers compared four wild communities in Taï National Park with four peer-raised sanctuary groups in Sierra Leone.
- Wild chimpanzees used raspberry calls almost exclusively during grooming, while sanctuary juveniles used them in more situations.
- An adult newcomer’s arrival was followed by a sanctuary group gradually adopting a more consistent raspberry pattern.
- The authors describe the findings as the first evidence of a learned signal convention in chimpanzee calls.
A 2026 study of 91 chimpanzees, ages ranging from birth to 55, reports the first evidence that some chimpanzee calls follow learned group conventions rather than fixed instinct alone.
Here, a convention means a shared rule about when and why to use a sound. The broader parallel is familiar: English speakers say “dog” and French speakers say “chien,” and either sound would work if the groups swapped them. Scientists had generally treated chimpanzee calls as largely instinctive and biologically fixed. The study tested that assumption.
The study appeared in the Proceedings of the National Academy of Sciences and focused on the raspberry, an unvoiced sound made with the lips, much like a person blowing a raspberry. Researchers from the CNRS Institute of Cognitive Sciences, the University of Warwick and the Taï Chimpanzee Project asked whether chimpanzees learn when and why to use a call.
Takeaway: The findings suggest that a chimpanzee’s social environment can shape the purpose of a sound it already makes.
How did the groups differ?
To test the idea, the team compared:
- Four wild communities at Taï National Park in Ivory Coast.
- Four communities of orphaned, peer-raised chimpanzees at Tacugama Chimpanzee Sanctuary in Sierra Leone.
Wild chimpanzees used the raspberry almost exclusively while grooming others. Sanctuary juveniles used the call across a much wider range of social situations. If the raspberry were purely instinctive, researchers would expect groups to use it in similar ways wherever they grew up.
The differences suggest that chimpanzees learn not only how to make the call, but when and why to use it. That supports a social-learning explanation, although the comparison alone cannot rule out every alternative.
Richard Moore, a philosopher at the University of Warwick and a study co-author, said:
In everyday communication, we use the words that we do only because our peers do too. It's communal practice that fixes their meaning, rather than features of the words themselves.
The discovery that this is true not just for natural languages but also some chimpanzee calls means there's more continuity between chimpanzees' vocal learning and our own than we previously suspected.
Takeaway: Chimpanzees appear to learn the social rules attached to a familiar call, much as people learn the shared meaning of words.
Can one adult change a group’s calls?
Researchers then introduced an adult newcomer to one sanctuary group. The group’s raspberry use gradually became more consistent and began to resemble the newcomer’s. This suggests adults can act as communication role models, helping a community settle on shared patterns.
The authors say they have shown learned, agreed use in chimpanzee calls for the first time. The apparent link between the sound and its use passed from one chimpanzee to another, rather than emerging wholly at birth.
Unlike humans, chimpanzees struggle to learn entirely new call sounds. The result suggests they can learn the functions of calls they already make, offering a route by which communication develops across generations.
“Even aspects of chimpanzee vocal communication that seemed fixed and unlearned may be shaped by learning, suggesting that there is still much to discover about their vocal repertoire,” said Antoine Valet, the study’s first author.
Takeaway: An adult can influence a group’s conventions, even when the group cannot readily invent new sounds.
Why might grooming matter?
One question remains: If the raspberry is learned, why do different populations use it in similar ways?
Catherine Crockford, a senior author at the CNRS Institute of Cognitive Sciences in Lyon, framed the puzzle:
If the raspberry is learned, why do different populations use it in similar ways?
One possibility is that, while grooming, as chimpanzees use their lips to extract parasites from another's fur, it may be easier to generate a vocalization that uses similar lip movements, a call that is known to prolong grooming bouts.
Communities may have found this useful independently, but that wouldn't change the fact that the call is a convention. We need more research to test it.
The proposal links physical ease with social benefit: similar lip movements may make the call easier to produce during grooming, and the call can prolong grooming. Independent usefulness would not erase its conventional status. Researchers still need to test the explanation.
Takeaway: Grooming may help explain where the convention arises, but the proposed mechanism remains unconfirmed.
What does this mean for the field?
The findings offer evidence, not a complete account of chimpanzee language. They address when and why an existing call gets used, not whether chimpanzees can readily invent new sounds. The group comparison and newcomer response point to social transmission, while the grooming explanation remains unconfirmed.
Roman Wittig, director of the Taï Chimpanzee Project and a study senior author, said:
Preserving wild chimpanzee populations is critical if we want to continue to understand the extent to which chimpanzees learn and perpetuate their vocal communication.
The paper, “A signal convention in natural chimpanzee communication,” by Antoine Valet and colleagues appeared in the Proceedings of the National Academy of Sciences in 2026. Its DOI is 10.1073/pnas.2606837123.
Takeaway: The study broadens the search for learning in chimpanzee communication, making the study of surviving wild populations especially important.
via phys.org/rss-feed/ (Source)
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Correspondent covering money, funding and market shifts around general science news at SciBeat.
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