3. The Hmong People Of China Can Communicate By Whistling
Whistling is not exclusive to the Hmong people of China. Several tribes around the world independently learned to communicate via whistling. However, they are usually located in mountainous regions where people live far apart. The Hmong live at the foot of the Himalayas.
The Hmong farmers whistle to chat on farms, while hunting in the jungle, and to send love messages at night. Everyone understands what the lovers are saying. But they do not recognize the people because a whistle is not individually identifiable like a voice. This allows the lovers to remain anonymous while passing messages. Some even add nonsense whistles to confuse the listeners.
A tribe on one of the Canary Islands also communicates via whistling. Their whistling language is called Silbo Gomero and sounds so similar to birdsong that some birds are imitating it.
Some Amazonian tribes also use whistling to communicate while hunting in the jungle. This is safer than speech because whistling will not startle game. The Inuit communities of the Bering Strait also use whistling to communicate when whale hunting.
Whistling has even been used in warfare. The Berbers of North Africa used it to pass secret messages during their resistance against France. During World War II, Australia hired Wam speakers from Papua New Guinea to transmit and decode whistled messages to prevent the interception of radio messages by the Japanese.