Chimp conversations reveal hidden grammar similar to human language

Chimps combine calls like words

For a long time, scientists thought that only humans used language with grammar. Other animals were seen as using simple, fixed calls – like single words without sentences. New findings show that chimpanzees have been “speaking” in more complex ways than we realized. Wild chimps in West Africa don’t just cry out one sound at a time; they combine calls almost like we combine words, following certain rules. A small change in a call can have a big effect. It turns out our ape cousins are putting sounds together to share more information, hinting that the roots of grammar might predate humans.

Researchers recorded over 4,300 vocalizations from 53 adult chimpanzees in Ivory Coast’s Taï National Park. They identified about a dozen distinct call types – the chimp “alphabet” of hoos, grunts, barks, screams and more. These calls were heard alone and in various combinations. By carefully observing what the chimps were doing when each call or combo was made, the scientists deciphered some meanings. What they found astonished them: chimps don’t stick to one method for combining calls, but use multiple strategies to change or expand what their calls mean. In other words, chimp communication isn’t random monkey business – it has structure.

Four ways chimps mix their calls

When putting calls together, the chimpanzees followed four simple patterns that resemble elements of human grammar:

• Combine to create new meaning – Joining two different calls can create a whole new message (Call A + Call B = Meaning C). It’s like how joining two words can form a new idea. For example, one chimp sound for “let’s travel” and another for “danger” might combine to mean “travel carefully". Researchers indeed saw cases where two calls together meant something not obvious from either call alone.

• Add to modify meaning – Adding one call to another can tweak the message, similar to adding a suffix or prefix in human language. One sound can act like a little modifier that changes the tone of the first. (Think of how adding “-less” to “fear” makes fearless, changing the meaning.) In chimp talk, a call that usually means “let’s go” could get an extra hoo sound added to specifically mean “let’s go together".

• Order matters – Flipping the order of two calls can change the meaning, just like how “dog bites man” versus “man bites dog” have very different meanings in English. Chimpanzees showed this pattern too. A “hoo + grunt” sequence was mostly used when the apes were settling down to feed or rest, but a “grunt + hoo” sequence happened during group travel or when two chimp groups met. Simply swapping the sequence of calls gave a new context.

• Idiom-like combinations – Sometimes a pair of calls means something entirely new, not directly tied to each call’s individual meaning. This is a non-compositional or “idiomatic” use, similar to how the phrase “go ape” in English has a meaning (to go crazy with excitement) that you wouldn’t guess from “go” or “ape” alone. Chimpanzees had their own special combos: one example was a call for resting combined with a friendly call that together signaled “let’s build a nest up in a tree” – a meaning that’s different from either call by itself. In fact, the combo “hoo + pant” meant preparing a safe treetop nest (to avoid predators) rather than just resting on the ground.

These four vocal “tricks” show that chimpanzee chatter has a versatile structure. A given sound’s meaning isn’t fixed – it can change depending on what other sound joins it or in what order. The findings suggest chimps essentially have a basic grammar toolkit for communication. This is the first time such richness has been seen outside humans. Most other animals studied – like certain monkeys – use at most one simple combining strategy (for instance, some monkeys add an “-oo” sound to an alarm call to change it from “Eagle above!” to a more general “Watch out!”). Those are useful, but limited, signals often only used in emergencies like predator warnings. Chimpanzees, however, mix and match calls in many ways across everyday situations. They can even communicate more than one idea at once with a single sequence, similar to how a short sentence can convey who is doing what, and why. It’s a super exciting discovery for scientists, who didn’t know our ape cousins had such a range of vocal expression.

More than just alarm calls

Why is this discovery important? For one thing, it shows that chimpanzees use their “words” (calls) far beyond just saying “Look out, a lion!” Researchers observed chimps combining calls in dozens of different social and daily contexts, not only when a leopard or eagle is near. They might string sounds together during relaxed feeding times, playful moments, reunions of friends, or times of conflict – basically throughout their day. One combined call, as mentioned, specifically meant “we’re making a tree nest”, indicating the apes were communicating a detailed plan (where to rest for safety). This goes beyond a simple shout; it’s more like a brief message. The chimp “vocabulary” of call combinations seems to be much larger and more flexible than what we see in other primates. In fact, the team documented 16 distinct two-call sequences (scientists call them “bigrams”), built from 12 different call types. And those are just the short sequences – chimpanzees also sometimes produce longer strings of three or more calls (a bit like an even longer word or phrase), which the researchers are now investigating.

All this suggests that chimpanzees can paint richer messages with sound than we assumed. “The chimp combinatorial vocal system is more complex than we previously thought", remarked one scientist. In other words, chimps have moved a step closer to language by using a kind of rudimentary grammar. Nature is full of surprises – one germ even evolved the ability to munch on medical plastic – and now we’ve learned our fellow apes share more of our communication toolkit than anyone guessed. Just as our brains can store yummy memories that drive us to crave sweets, chimp brains seem capable of managing a mental “dictionary” of calls and their combinations. This newfound complexity in chimp chatter is exciting for understanding how language evolution might have begun.

Clues to language evolution

Scientists are interested in what these findings mean for the origins of human language. Humans are the only species on Earth that have full-blown language, with grammar that lets us create an infinite number of sentences. But if chimpanzees (and likely other great apes) also combine calls following certain rules, it hints that the building blocks of grammar were present in our common ancestor. In fact, another study in 2025 showed that bonobos – our other closest ape relatives – also string together calls with different meanings, much like forming simple phrases. Bonobos were found to use one call to modify another’s meaning, a bit like how adding “bad” to “dancer” changes the meaning of “dancer”. This was reported in the journal Science, suggesting that key aspects of language are evolutionarily ancient. Chimpanzees, according to the new research, take this to an even more complex level. If both chimps and bonobos do it, their last common ancestor with humans (which lived roughly 6 to 10 million years ago) might have had at least a rudimentary combinatorial communication system.

These apes don’t have full human language – they don’t seem to have true words or grammar as rich as ours. But they clearly show a capacity to recombine sounds to convey new information, which is a fundamental step on the way to language. This challenges the old view from last century that great ape calls are just emotional outbursts with no real structure. Instead, chimps are actively using rules (even if simple ones) to talk about their world. It’s as if they have some pieces of the language puzzle, even though they’ll never complete the whole picture like humans have. The discovery narrows the gap between human speech and animal communication. It also raises the question: have we underestimated other animals too? Perhaps complex communication isn’t unique to us at all, and other species (maybe whales, elephants, or even birds) have hidden grammatical tricks waiting to be discovered. Each new insight like this helps scientists understand how our own language might have evolved from simpler beginnings. And it reminds us that we’re not alone in using creative communication – our animal cousins have been chatting in their own clever ways all along.

SlothMD takeaway

It’s amazing to learn that wild chimpanzees use a form of “grammar” in their calls. Discoveries like this show how staying curious about science can change our understanding of the world. Just as chimps combine sounds to share important messages, we at SlothMD believe in combining knowledge and care to help people stay healthy and informed. While we humans have the most complex language, studies of our primate relatives give us humble insight into where we came from – and that’s something to go ape about in the best way! SlothMD loves exploring these scientific curiosities and is here to keep you informed every step of the way. After all, staying informed (and a bit curious) is a smart step toward better health and understanding of our amazing world.

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