A key element of human language has been discovered in babbler bird.
Stringing together meaningless sounds to create meaningful signals was previously thought to be the preserve of humans alone, but the new study has revealed that babbler birds are also able to communicate in this way.
Researchers at the Universities of Exeter and Zurich discovered that the chestnut-crowned babbler, a highly social bird found in the Australian Outback, has the ability to convey new meaning by rearranging the meaningless sounds in its calls.
This babbler bird communication is reminiscent of the way humans form meaningful words. The research findings, which are reveal a potential early step in the emergence of the elaborate language systems we use today.
Lead author Sabrina Engesser from the University of Zurich said that although previous studies indicate that animals, particularly birds, are capable of stringing different sounds together as part of a complex song, these songs generally lack a specific meaning and changing the arrangement of sounds within a song does not seem to alter its overall message.
In contrast to most songbirds, chestnut-crowned babblers do not sing. Instead its extensive vocal repertoire is characterised by discrete calls made up of smaller acoustically distinct individual sounds, she added.
Researcher think that babbler birds may choose to rearrange sounds to code new meaning because doing so through combining two existing sounds is quicker than evolving a new sound altogether, said co-author Andy Russell.
The researchers noticed that chestnut-crowned babblers reused two sounds “A” and “B” in different arrangements when performing specific behaviours. When flying, the birds produced a flight call “AB”, but when feeding chicks in the nest they emitted “BAB” prompt calls.
The authors report that in the chestnut-crowned babbler, the first sound element “B” is what seems to differentiate the meaning between flight and prompt vocalisations, akin to cat and at in English, where the c represents the meaning differentiating element, or phoneme.
The study is published in the journal PLOS Biology.