Turkish communities living in the mountains in the north east of the country use a remarkable whistling language to communicate. Around 10,000 people use the bird-like whistle, which researchers suggest is the first known form of language to use both sides of the brain.

Whistlers usually speak Turkish when talking near each other, but switch to whistling when they want to convey a message over longer distances, which can be up to five kilometers. The whistling language has the same vocabulary and grammatical structure as Turkish, it’s just a different format. Scientists have previously assumed that all spoken language, written texts and sign language mainly utilize the left hemisphere, but this doesn't seem to be the case for the whistling language.

“In all languages, tonal or atonal, click or sign language, written or spoken, it’s so far been the left hemisphere that appears to do most of the interpretation,” lead author Dr. Onur Güntürkün told New Scientist. “Now, we’ve shown for the first time equal contributions from both hemispheres.”

For the study, published in the journal Current Biology, researchers at the Ruhr University Bochum tested 31 people who were fluent in both spoken and whistled Turkish and lived in the village Kuṣköy. During the experiment, participants listened to whistled or spoken Turkish syllables through headphones.

As Science Magazine explains, the format of the experiment is a unique take on a classic test where scientists simultaneously play one of two slightly different symbols – such as “ba” and “da” – into the participants’ left ear and the other in the right. Researchers would then ask participants to relay what they heard. These tests usually reveal what participants hear in their right ear, which corresponds to the speech sound processing centers in the left hemisphere.

^{A village in Turkey where some inhabitants have mastered whistled Turkish. Onur Güntürkün.}

When the Turkish syllables were spoken, researchers found that the participants understood the syllable played from the right ear a lot more frequently, which suggests a dominance of the left brain hemisphere. When they did the same test in whistled Turkish, however, participants understood the syllables played in both ears. The asymmetry found in spoken Turkish didn't exist when the syllables were whispered.

Researchers note in a statement that: “The results have shown that brain asymmetries occur at a very early signal processing stage.” Though it’s unclear why this asymmetry doesn't occur in whistled Turkish. Güntürkün told the New Yorker:  “They [the results] tell us that the organization of our brain, in terms of its asymmetrical structure, is not as fixed as we assume.” 

“The way information is given to us appears to change the architecture of our brain in a radical way,” he added.

Researchers speculate on whether these findings could have implications for stroke victims. Güntürkün would like to further investigate whether Turkish whistlers who have suffered from a stroke affecting their left hemisphere could still whistle Turkish.  

[H/T New Scientist]