STUDY: Bonobos create phrases in similar ways to humans
Compositionality is the ability to combine meaningful units into larger structures (e.g., sentences) whose meaning is derived from the meaning of its units and the way they are combined. By extensively researching the vocal communication of bonobos in their natural habitat at Kokolopori Community Reserve in the Democratic Republic of the Congo, the researchers found that vocal communication between bonobos – our closest living relatives, along with chimpanzees – relies extensively on compositionality, just like human language.
MELISSA BERTHET: Humans can effortlessly talk about an infinite number of topics, from neuroscience to pink elephants, by combining words into sentences. This is thanks to compositionality: the ability to combine meaningful units into larger structures whose meaning is derived from the meaning of its units and the way they are combined.
For years, scientists believed that only humans extensively used compositionality. Animal communication was thought to be mostly a mere random assortment of calls, with only rare instances of compositionality. However, our new study, recently published in the journal Science, says otherwise.
By extensively researching the vocal communication of bonobos in their natural habitat, the Kokolopori Community Reserve in the Democratic Republic of the Congo, we found that vocal communication between bonobos – our closest living relatives, along with chimpanzees – relies extensively on compositionality, just like human language…
Investigating compositionality in animals first requires a strong understanding of what single calls and their combinations mean. This has long presented a challenge, since accessing the minds of animals and reliably decoding the meaning of their calls is difficult…
Previous studies in birds and primates have demonstrated that animals can form trivially compositional structures. However, there has previously been little clear evidence of nontrivial compositionality in animals, reinforcing the idea that this ability is uniquely human…
We used a method derived from distributional semantics, a linguistic approach that maps words based on their meaning similarities, with the idea that words with close meanings are used in similar contexts. For example, the words “shark” and “animal” are often used alongside similar words, such as “fish” and “predator”, suggesting that they have related meanings.
In contrast, “animal” and “bank” are used in different contexts, they have less related meanings. This approach allows to reliably represent and measure the relationship between different words’ meanings… By applying this methodology to bonobo vocalisations, we mapped the meaning of calls and call combinations within a semantic space based on their context of use…
We identified four call combinations whose meaning was related to the meaning of their single parts, a key hallmark of compositionality. Importantly, every call type appeared in at least one compositional combination, similarly to how every word can occur in a phrase in human language. This suggests that, like in human language, compositionality is a fundamental feature of bonobo communication.
Furthermore, three of the call combinations bore a striking resemblance to the more complex nontrivial compositional structures seen in human language. This suggests that the capacity to combine call types in complex ways is not as unique to humans as we once thought, hinting that this capacity may have deeper evolutionary roots than previously assumed…
An important implication of this research is the insight it provides into the evolutionary roots of language’s compositional nature. If our bonobo cousins rely extensively on compositionality, just like we do, then our last common ancestor likely did as well. SOURCE…
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