Nicaraguan Sign Language (NSL) has evolved from a series of crude pantomimes to a proper language, complete with its own grammar, in just 3 decades. As researchers report in the 17 September issue of Science, it's the language's newest speakers--young children--who have led the way in setting grammar rules and creating new forms of expression. The researchers say their findings bolster the argument, long made by some linguists, that children's brains are wired for language innovation.
In 1977, a school for the deaf was established in Managua, Nicaragua, providing a desperately needed opportunity for deaf Nicaraguans, who had been isolated. It also gave cognitive scientists and linguists a unique opportunity to study human communication. The newly formed deaf community quickly modified idiosyncratic gestures to create common usages, and each new class of students refined the language. Now more than 800 speakers from ages 4 to 45 use NSL.
Cognitive scientist Ann Senghas of Barnard College of Columbia University in New York City and colleagues have been studying the language's evolution since the early 1990s. They recently conducted a study of three categories of NSL users grouped by the decade in which they learned NSL. Older NSL users often contribute new vocabulary, but no new grammar rules or signing techniques, the researchers found.
The youngest learners, on the other hand, are more innovative. For example, they sign to their right or left side, or high or low, to indicate who is doing what. Younger NSL users depict simultaneous actions by embedding one sign within another and describe motion events using sign words for the direction of action (such as up or down) and the manner of action (such as slow or fast). Older speakers generally don't adopt the newest NSL innovations and sometimes complain that the youngsters aren't "doing it right," Senghas says. That suggests to her that there may be a biological reason why significant language refinements are more likely to occur during childhood.
The study provides a "dramatic and important" case study of the evolution of a "rough-and-ready pantomime" into a classically defined language, says linguist Lila Gleitman of the University of Pennsylvania in Philadelphia. Even so, not everyone agrees that the work demonstrates that only the young can be language innovators. "Differences between children and adults are a matter of skill in standardizing language,” not overall aptitude, says cognitive scientist Daniel Slobin of the University of California, Berkeley.