by 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.
A bonobo dictionary
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.
To remedy this, we developed a new way of reliably determining the meaning of bonobo vocalisations, and used it to determine the meaning of all of their single calls and combinations.
We assumed that a bonobo call can have different types of meaning. It can give an order (“Run”), announce future actions (“I will travel”), express the internal states (“I am afraid”) or refer to external events (“There is a predator”).
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