Bonobos Have 'Speech' Similar to Humans with Behavioral Contexts Linked to Emotion
It turns out that bonobos may have "speech" that similar to humans. Scientists have found that these apes can vocalize in a wide range of emotional states and situations, similar to how human infants are able to produce vocalizations.
Animal vocalizations are usually made in relatively narrow behavioral contexts linked to emotional states, such as to express aggressive motivation or to warn about potential predators. In contrast, humans exhibit "functional flexibility" when vocalization in a variety of situations.
In this latest study, the researchers looked at wild bonobos and found that in this species, individuals produce a call type, known as the "peep," across a range of positive, negative and neutral situations. Peeps are high-pitched vocalizations and are produced with a closed mouth.
The scientists found broad similarity in the acoustic similarity across different contexts. This suggests contextual flexibility in the call. Similar to human infants, recipients have to make pragmatic inferences about the meaning of the call across contexts.
The functional flexibility seen in bonobos could represent an important evolutionary transition from functional fixed animal vocalization towards flexible human vocalizations. This particular transition occurred about 6 to 10 million years ago in the shared common ancestor between humans and great apes. It may be that many of the core features of human language have deep roots in the primate lineage.
"More research needs to be done on our great ape relatives before we can make conclusions about human uniqueness," said Zanna Clay, one of the researchers, in a news release. "The more we look, the more continuity we find among animals and humans."
The findings are published in the journal PeerJ.
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