La Gomera is small and hard to cross. Deep ravines cut the Canary Island in such a way that two people can see each other without being able to meet in under an hour. The paths follow the ridges and the ravines, not the straight line. Shouting does not help, the voice does not carry far enough. A whistle does.
Out of that mismatch came Silbo Gomero, a whistled form of Spanish. It is not a code of agreed signals in which one whistle means come here and two mean danger. It is the language itself, transposed into pitch. Two different whistled tones stand for the five Spanish vowels, four more for the consonants. Anyone who commands Silbo whistles not messages but sentences, and the person across the valley understands them because they speak Spanish.
Five kilometres instead of fifty metres
The range explains why the effort paid off: messages travel up to five kilometres. For a herder on the far side of a ravine that was the difference between news in seconds and a walk of several hours. What was whistled was therefore nothing ceremonial, but the everyday business you would otherwise have had to walk across for.
Anyone who commands Silbo whistles not messages, but sentences.
— TerraTally · Languages desk
Whistled languages exist in several places in the world, almost always in broken terrain where sound carries across a valley better than any path does. What is special about Silbo is therefore not that it exists but the state it is in. It is the only whistled language that is fully developed and practised by a large community. Fully developed means there is hardly anything that can be said in Spanish but not whistled. The island has more than 22,000 inhabitants, and the whistling there is not the speciality of a few.
Scale
5
Kilometres of range
1999
Compulsory subject in island schools
2009
UNESCO heritage
That this is still the case was not a given. The telephone, and later the mobile network, made Silbo practically superfluous. Anyone who wanted to get word from one slope to the other simply called. The number of whistlers fell sharply, the knowledge concentrated among older people, and children grew up with a skill they saw no use for. A dying language, going by the usual course of things.
The course was interrupted because somebody made a decision. Since 1999 Silbo has been taught in the island's schools, not as an afternoon option but in regular lessons. In 2009 UNESCO added it to the Representative List of the Intangible Cultural Heritage, which gave the subject further backing. Today almost every islander understands it. It is practised by the old, who never unlearned it, and by the young, who learned it in the classroom.
Silbo is not a museum piece, then, but a counterexample. Languages do not disappear because they become useless; Silbo became useless decades ago. They disappear when nobody makes sure they are passed on. On La Gomera somebody did, and in time.