Herders' Whistled Language Shows Brain's Flexibility

James Owen in London
for National Geographic News
January 5, 2005
Shepherds who whistle to each other across the rocky terrain of the Canary Islands off northwest Africa are shedding light on the language-processing abilities of the human brain, according to scientists.

Researchers say the endangered whistled "language'" of Gomera island activates parts of the brain normally associated with spoken language, suggesting that the brain is remarkably flexible in its ability to interpret sounds as language.

The findings are published in tomorrow's issue of the science journal Nature.

"Science has developed the idea of brain areas that are dedicated to language, and we are starting to understand the scope of signals that can be recognized as language," said David Corina, co-author of the study and associate professor of psychology at the University of Washington in Seattle.

Silbo Gomero is a substitute for Spanish, with individual words recoded into whistles. Vowels and consonants are replaced by tones that are whistled at different frequencies. ("Silbo" comes from the Spanish "silbar"—to whistle.)

Known as silbadores, the whistlers of Gomera are traditionally shepherds and other isolated mountain folk. Their novel means of staying in touch allows them to communicate over long distances—Silbador whistles can travel up to six miles (ten kilometers).

"Spanish consonants are mapped into four different whistles and the five vowels into two whistles," explained lead researcher Manuel Carreiras, psychology professor at the University of La Laguna on the Canary island of Tenerife. "There is much more ambiguity in the whistled signal than in the spoken signal," he added.

Because whistled "words" can be hard to distinguish, silbadores also rely on repetition and context to make themselves understood.

Brain Activity

The study team used neuroimaging equipment to contrast the brain activity of silbadores while listening to whistled and spoken Spanish. Results showed the left temporal lobe of the brain, which is usually associated with spoken language, was engaged during the processing of Silbo Gomero.

The researchers found that other regions in the brain's frontal lobe also responded to the whistles, including those activated in response to sign language among deaf people. However, brain areas activated in experienced Silbadores differed significantly from those in nonwhistlers who listened to the same sounds but could not understand them.

"Our results provide more evidence about the flexibility of human capacity for language in a variety of forms," Corina said. "These data suggest that left-hemisphere language regions are uniquely adapted for communicative purposes, independent of the modality of signal. The non-Silbo speakers were not recognizing Silbo as a language. They had nothing to grab onto, so multiple areas of their brains were activated."

Carreiras said silbadores are able to pass a surprising amount of information via their whistles.

"The shepherds could whistle a conversation about relativity theory if they wanted, however, they usually talk about other things," he said. "In daily life they use whistles to communicate short commands, but any Spanish sentence could be whistled."

A silbador sticks a finger in his or her mouth to increase the whistle's pitch. The other hand can be cupped like a megaphone to direct the sound.

African Roots

Carreiras says the origins of Silbo Gomero remain obscure but that indigenous Canary Islanders, who were of North African extraction, already had a whistled language when Spain conquered the volcanic islands in the 15th century.

Whistled languages survive today in Papua New Guinea, Mexico, Vietnam, Guyana, China, Nepal, Senegal, and a few mountainous pockets in southern Europe. There are thought to be as many as 70 whistled languages still in use, though only 12 have been described and studied scientifically.

This form of communication is an adaptation found among cultures where people are often isolated from each other, according to Julien Meyer, a researcher at the Institute of Human Sciences in Lyon, France. "They are mostly used in mountains or dense forests," he said.

Whistled languages, Meyer said, "are quite clearly defined and represent an original adaptation of the spoken language—like a local cellular phone—for the needs of isolated human groups."

But with modern communication technologies now widely available, researchers say whistled languages like Silbo Gomero are threatened with extinction.

"It was a way of communication over deep valleys and steep mountains," Carreiras said. "Now you can do that with cell phones."

With dwindling numbers of Gomera islanders still fluent in the language, Canaries authorities are taking steps to try to ensure its survival.

Since 1999 Silbo Gomero has been taught in all of Gomera's elementary schools. In addition, locals are seeking assistance from the United Nations Educational, Scientific and Cultural Organization (UNESCO).

"The local authorities are trying to get an award from UNESCO to declare [Silbo Gomero] as something that should be preserved for humanity," Carreiras added.

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