Deep in the rainforests of the Democratic Republic of the Congo, researchers have discovered that bonobos (Pan paniscus) may have far more sophisticated communication abilities than previously believed. A study led by Mélissa Berthet, a primatologist and linguist at the University of Rennes in France, found that bonobos can combine calls into complex phrases — a behavior long thought to be uniquely human.
During six months of observation, Berthet recorded 700 calls from 30 adult bonobos. She found that the primates regularly combined distinct calls in ways that altered or expanded their meanings. For example, a yelp meaning “let’s do this” was paired with a grunt meaning “look at me” to create a phrase interpreted as, “Look at what I’m doing, and let’s do this all together.” In another case, a peep expressing “I would like to do this” was followed by a whistle for “let’s stay together,” apparently used to maintain peace in social contexts.
The findings, reported in Nature, challenge long-standing ideas about what makes human language special. Linguists have traditionally believed that only humans use “compositionality” — the ability to combine meaningful sounds into expressions whose meaning derives from their parts. But growing evidence from bonobos, chimpanzees, birds, and even whales suggests otherwise.
In 2016, researchers studying Japanese tits (Parus minor) showed that the birds combined alarm and recruitment calls into phrases with distinct meanings. More recently, studies of chimpanzees revealed that they also merge calls in ways that convey new information, sometimes producing meanings not directly traceable to the original sounds.
What makes the bonobo study remarkable is the variety of ways the animals use compositionality. Berthet’s team found four different types of call combinations, including cases where one call modified another — similar to how humans use adjectives to alter meaning, as in “a terrible actor.” Evolutionary biologist Cédric Girard-Buttoz of the Lyon Neuroscience Research Center, who has studied chimpanzee communication, says such findings mark an important step toward understanding the building blocks of language.
The implications stretch beyond primates. Projects like CETI (Cetacean Translation Initiative) are applying artificial intelligence to decode the communication of sperm whales, which appear to have their own “phonetic alphabet.” Similarly, AI tools are being tested on birds, dolphins, and elephants, raising hopes that humans might one day “talk back” to other species.
Still, whether this qualifies as true “language” remains controversial. Some scientists argue that features such as displacement (the ability to talk about things not present) and productivity (creating novel expressions) are unique to humans. Others suggest that animal communication systems may be different in kind, not just degree.
Berthet herself is cautious. While her study blurs the line between human and animal communication, she questions whether animals would even want to engage in two-way conversations with humans. “I’m not sure I want to be able to communicate with them,” she says.
As Nature notes, these discoveries may not rewrite the definition of language just yet — but they do open new windows into the minds of other species, showing that the roots of complex communication run deeper in the animal kingdom than once believed.
