Human language is extremely complex and multifaceted, but how unique is it really compared to the rest of the animal kingdom? As researchers have now found, not only we, but also bonobos, can combine their calls according to complex, language -like rules. The primates belonging to our closest relatives communicate more human -like than expected. Our language skills may even go back to a common ancestor, as the team in “Science” reports.
An essential feature of the human language is the ability to combine individual elements into complex, meaningful structures – for example, to set individual words. One also speaks of compositionality. In the simplest form, we combine elements that independently contribute to the importance of the whole. An example: a blond dancer is both blond and a dancer. One word does not affect the other in its meaning. If we were learned that the dancer is also a doctor, he would also be a blond doctor.
However, there is talk of complex compositionality if individual elements modify the importance of others. So a bad dancer is not a bad person who happens to be a dancer. If he were a doctor at the same time, it would not automatically make him a bad doctor. The distinction between simple and complex compositionality is important, among other things, when it comes to language skills in the animal kingdom. Because while the former has already been observed in other animals such as primates and birds, there has been no direct evidence for the latter so far.
The first bonobo dictionary
But that has changed now. In order to find out whether our closest relatives are capable of complex compositionality, researchers around Mélissa Berthet from the University of Zurich have now examined the language skills of Bonobos more closely. To do this, they analyzed around 700 shots of wild bonobos from the Democratic Republic of Congo and evaluated them using various linguistic methods that were originally developed for research into human language.
“We were able to create a kind of bonobo dictionary-a complete list of bonobo calls and its meanings,” explains Berthet. “This is an important step to understand the communication of other species, as we for the first time determine the meaning of sounds in the entire sound repertoire of an animal.” After the team decoded the importance of the individual bonobo calls, it finally examined their combinations with another linguistic approach. “This way we were able to measure how the meaning of individual calls is related to that of call combinations,” says senior author Simon Townsend.
Human language is not so unique
The result: The calls of the bonobos could be summarized in four different composition structures – three of which were cases of complex compositionality. “This indicates that the ability to combine sounds in a complex way is not as unique for humans as we thought,” reports Berthet. However, it could still be that this form of the language talent is at least unique for the group of primates related to us.
“People and Bonobos had a common ancestors seven to 13 million years ago and share many characteristics of their descent-probably also the compositionality of their communication,” assumes co-author Martin Surbeck from Harvard University. “Our results indicate that our ancestors had this ability at least seven million years ago – if not earlier,” adds Townsend. The ability to form complex meanings from smaller sounds would have existed long before the human language.
Source: Mélissa Berthet (University of Zurich, Zurich, Switzerland) et al., Science, Doi: 10.1126/science.adv1170