The inhabitants of La Gomera in the Canary Islands still 'speak' an ancient whistling language that was once necessary for communicating across long distances, valleys and ravines. The language is called Silbo Gomero, and is taught to all children in school, alongside Spanish. In 2009, UNESCO declared the language a 'Masterpiece of the Oral and Intangible Heritage of Humanity'. You can read more about Silbo Gomero here, or listen to a BBC programme about it here. Two short films on the language can be seen below.