Bonobos’ Communication May Hold Human-Like Qualities: Study Finds Similarity in Vocalizations and Language Traits

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Researchers attempted to decode bonobo calls by recording their social context, then analyzed how the primates string together these vocalizations

Margherita Bassi – Daily Correspondent

April 4, 2025 4:54 p.m.

For centuries, the intricacies of human language have been viewed as a defining characteristic setting us apart from other species. However, recent findings indicate that our linguistic abilities may have counterparts in other primates, specifically wild bonobos, who share a close genetic lineage with humans.

A study published in the journal Science examines how bonobos communicate vocally within various social frameworks and suggests that their vocalizations operate on complex levels comparable to human language. “While bonobos do not possess a language in the same sense that humans do, our research reveals that certain linguistic features can be observed in their communication,” explains Simon Townsend, a psychologist at the University of Zurich and co-author of the study.

The researchers focused on the linguistic concept of compositionality, which addresses how the meanings of phrases can arise from the meanings of their individual words and their interrelations. There are two types of compositionality: trivial, where the meaning is simply a sum of the parts (e.g., a “blond dancer” refers to someone who is both blond and a dancer), and nontrivial, where a word modifies the meaning of another (e.g., a “bad dancer” specifies the quality of the dancing, not the dancer’s overall character).

Traditionally, the capacity for nontrivial compositionality has been regarded as a human-exclusive characteristic. Townsend remarks on its significance, stating, “This aspect sustains the creative and adaptive nature of language, allowing for the construction of novel phrases.”

The study found that bonobos utilize both forms of compositionality in their communication. To reach this conclusion, the research team observed adult bonobos at the Kokolopori Bonobo Reserve in the Democratic Republic of the Congo, recording approximately 700 calls alongside contextual details. They then applied linguistic analytical techniques to decipher the meanings behind individual calls.

According to lead author Mélissa Berthet, an evolutionary anthropologist, the research essentially created a “dictionary” of bonobo vocalizations, linking specific sounds with their meanings. For instance, the grunt signifies “look at me” while the yelp conveys a command such as “let’s do that.”

The researchers classified sounds into distinct categories—like peep, grunt, yelp, high-hoot, and low-hoot—and analyzed how the different categories combined to form contextual meanings. They identified examples of nontrivial compositionality through specific combinations of calls, such as a high-hoot combined with a low-hoot indicating a state of distress, or a peep followed by a whistle used during intimate social interactions.

Although the nontrivial compositionality observed in bonobos is simpler compared to humans, Townsend views it as a significant advancement in understanding the similarities between human and animal communication systems. Past studies hinted at compositionality in chimpanzees, but this research marks the first definitive evidence of nontrivial syntax in any species beyond humans, according to evolutionary biologist Maël Leroux, who did not take part in the study.

Despite this groundbreaking discovery, not all experts are convinced. Cognitive scientist Thom Scott-Phillips criticizes the criteria used to interpret the bonobos’ vocalizations and suggests that even simpler forms of signaling seen in microorganisms might meet similar standards. He poses a challenge: “If they were to conduct similar studies with bacteria and find no results, that would prompt a rethink.”

Should these findings be validated, they hold profound implications for our understanding of linguistic evolution. Notably, they propose that nontrivial compositionality could date back to a common ancestor of bonobos and humans, who existed around 7 to 13 million years ago. As Martin Surbeck, another co-author of the study, points out, the fundamental cognitive elements enabling this type of communication may be ancient. “It suggests that the cognitive building blocks for this capability are at least seven million years old,” Townsend concludes, marking a noteworthy insight into the evolutionary roots of language.

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