Scientists Find Possible Signs of Language in Bonobo Calls

On April 3, 2025, scientists studying bonobos and chimpanzees discovered that bonobos may combine vocal calls to create new meanings. The research was conducted in the Kokolopori Bonobo Reserve in the Democratic Republic of Congo to explore the roots of human language and investigate whether the bonobos share basic language-like abilities.

scientists has discovered that bonobos, close relatives of chimpanzees, may string sounds together to create new meanings, a feature of human language called compositionality. This finding, published in Science on June 12, 2025, suggests the roots of language might date back millions of years, but many scholars are skeptical about its relevance to human language. “The present findings don’t tell us anything about the evolution of language,” said Johan Bolhuis, a neurobiologist at Utrecht University in the Netherlands.

Scientists studied and recorded 400 hours of bonobo calls in the Democratic Republic of Congo. They identified several pairs of calls that seemed to carry combined meanings, expressing both “pay attention” and “I’m in distress.”

Unlike most animals who used one , the bonobos combined words to create complex meanings. For example, they used a “waa-bark” call to summon others and an “alarm-huu” call when scared. When these two calls were combined, it meant, “Come help me with this snake!”

This is called compositionality, an essential element in language. “It’s the force behind language’s creativity and productivity,” said Simon Townsend, a psychologist at the Switzerland University of Zurich. “Theoretically, you can come up with any phrase that has never been uttered before.”

Melissa Berthet, a postdoctoral researcher in Dr. Townsend’s lab used mathematical techniques to learn how words are related to each other. She mapped the recordings’ bonobo calls; the closer the calls appeared to each other on the map, the more similar they were. The bonobos mostly used 16 pairs of calls, and most pairs showed up on the map in the same area as the two individual sounds making them, showing their combination had no special meaning. Four pairs of calls didn’t follow this. One pair combined a high hoot, drawing the attention of others, and a low hoot, showing the bonobo is excited. It meant, ‘Pay attention to me because I am distressed.’ “Here we show actually bonobos have several compositional structures, and they use them a lot.” Dr. Berthet said. Together, the two studies on bonobos suggest that our common ancestor with these apes also possessed compositionality.

However, some experts remain skeptical, arguing that true language also requires complex grammar— which these apes don’t appear to use. Dr. Bolhuis questioned whether the new study could actually detect compositionality in bonobos. “Compositionality is not just about combining two words,” he said. It’s also about following rules of syntax to assemble words into phrases and bigger units of meaning.

These discoveries suggest that the common ancestor of humans, chimpanzees, and bonobos might have had the beginnings of language communication. Bonobos may combine calls to create new meanings suggests the roots of language could date back millions of years.

Sources:

https://phys.org/news/2025-04-bonobos-phrases-similar-ways-humans.html

https://nypost.com/2025/04/07/science/bonobos-complex-language-mimics-humans-scientists-claim/

https://www.science.org/content/article/uniquely-human-language-capacity-found-bonobos