for National Geographic News
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.
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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 distancesSilbador 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.
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."
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