Japanese great tits communicate surprisingly like humans. The combination and order of words and phrases help us shape the meaning of a sentence and these birds may use a similar structure, according to a new study published Tuesday in the journal Nature Communications.
If someone tells you “Come to the dark side. We have cookies” you would understand and probably want to go there, or not. That phrase would have a different meaning if the sentences were separated or ordered differently. The way it is originally written, it means that someone is trying to persuade you to go to a place because they have cookies there and you would probably want to have some.
Japanese scientists found that these particularly vocal songbirds also use a compositional syntax in their calls. They combine different calls to communicate a compound meaning, which was previously thought to be unique to human language.
Study lead author Toshitaka N. Suzuki and his research team had realized the Japanese great tits used different sounds and combinations of sounds in a wide variety of contexts.
They chirp, warble, peep, twitter and sing to warn that danger is near, to tell one another where a food source is located or to woo mates. Suzuki said he and his colleagues wanted to know if these calls were constituted by distinct elements with different meanings.
Great tits use an intelligent structure to form sentences
Researchers listened and broke down the birds’ calls into notes in order to better understand how the great tits used them individually and combined in a string.
The scientist identified a string of notes used to warn other birds to scan for predators and referred to it as the “ABC” call and found that it was often followed by the “D” call, which the great tits used to tell other birds to approach. In English, it would be something like “come here”. Combined, the call would mean “Scan for predators and come here”.
In order to get there and understand the meaning of the calls, the research team observed the birds’ reactions to hearing of specific recorded calls that the scientists projected over a loudspeaker.
Those great tits hearing an ABC call would look for a predator or some other danger by scanning the horizon, while those birds hearing a D call would simply move in the direction of the call’s source join a mate in their nest, to find a food source or whatever reason they had been told to move toward the bird who called.
The order matters
The team came up with the hypothesis that the combination of the two calls into ABC-D would produce a compound meaning, proving compositional syntax. The researchers were thrilled when they observed that the birds moved toward the sound but scanned the horizon for predators first.
However, the great tits could have simply responded to both calls separately. After thinking about this possibility, the researchers reversed the calls and formed a D-ABC call to see if the birds showed the same behavior.
They discovered that the order of the sounds does matter. When hearing that composition, the great tits seemed confused and rarely approached the sound or scanned the horizon.
“These findings demonstrate that Japanese great tits have evolved compositional syntax by which different meanings are combined into a compound meaning through a note ordering rule,” Suzuki said, as reported by Christian Science Monitor.
Source: Washington Post