Where in the world do people communicate by whistling?

The answer

Whistled languages transpose the phonemes of spoken language into whistled melodies, enabling communication across distances of 2 to 8 kilometers in mountainous terrain. Silbo Gomero, used on the Canary Island of La Gomera, was inscribed by UNESCO in 2009 as Intangible Cultural Heritage and is now taught in all island schools. Turkey's kuş dili ('bird language') in the Pontic mountains of Giresun province was recognized by UNESCO in 2017. Whistled forms of Mazatec exist in Oaxaca, Mexico, and the Hmong in Southeast Asia whistle tonal language across valleys. Researchers have documented over 70 whistled language cultures worldwide. A 2005 study in Nature by Manuel Carreiras showed that Silbo speakers process whistled language in the same brain regions as spoken language, confirming these are true linguistic systems rather than simple signal codes.