What the chestnut-crowned babbler lacks in flashy plumage, it makes up for with sophisticated language.
Decoding the calls of the chestnut-crowned babbler, a group of European researchers discovered that it communicates using word-like bits of sound. This highly social Australian bird rearranges the different sounds in its songs and calls to create "words" with unique meanings, the researchers report in the journal PLOS Biology.
"This is the first time that the capacity to generate new meaning from rearranging meaningless elements has been shown to exist outside of humans," said study co-author Simon Townsend from the University of Zurich in a statement. "Although this so-called phoneme structuring is of a very simple kind, it might help us understand how the ability to generate new meaning initially evolved in humans."
Among the many sounds that the babblers use are two common ones the researchers labeled "A" and "B." They noticed that the birds would reuse these two sounds in different arrangements, depending on the behavior they were carrying out. Flight was consistently accompanied by an "AB" call, while "BAB" calls accompanied feeding time for the chicks.
To test whether these different sounds arrangements had specific and unique meanings, the researchers played these avian "words" constructed out of the "syllables" A and B and watched the birds' behavior. Sure enough, when the birds heard the flight call "AB," they responded by looking up for other birds. Likewise, the feeding call "BAB" prompted the birds to look toward their nest.
This is similar to the way that humans use basic units of sound known as phonemes to create new meaning using the same sounds. The word "phoneme," for example, has five phonemes in it: ph, o, n, e, and m.
"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," said lead author Sabrina Engesser of the University of Zurich in a statement.
But for the chestnut-crowned babbler, the meaning of an entire "word" or "phrase" transcends the meaning of each of its constituent sounds. The researchers provided further evidence for this by taking a recording of an "AB" flight call and splicing it into a "BAB" feeding call. The birds responded the same way they did to an unedited recording of a "BAB" feeding call.
The presence of this phenomenon (or phonemenon, if you will) in a bird suggests that the use of phonemes is fundamental to the development of complex language. Indeed, as Townsend said in a statement, "it could be that when phoneme structuring first got off the ground in our hominid ancestors, this is the form it initially took."
Photo: Ron Knight | Flickr
