The birth of a language
Deaf children reveal brain's ability to break down concepts.
A group of deaf Nicaraguan children who have created their own way of signing are giving linguists a precious glimpse of a language in its infancy. The kids are revealing how our brains are wired for learning language.
It has long been debated to what extent our brains are a 'blank slate', able to learn any structure of language to which we are exposed, or whether they are hard-wired with grammatical rules. Existing languages do share fundamental rules. But this may simply be because different languages have influenced each other as they evolved.
Linguists have attempted to answer the question by examining languages as they arise. For example, when people who speak different languages are pulled together, as they were by immigration or slavery, they rapidly evolve a pidgin language that can be polished over the years into a more sophisticated creole.
But in these cases the communications are based on pre-existing languages. The Nicaraguan children are special because they have created a language from scratch. Deaf kids in the country lived in effective isolation until they were brought together in specialist schools in the late 1970s and 80s.
Once the deaf children started to mingle, they began to communicate in their free time using gestures. They tend to stick with the signs they have acquired by the time they reach adolescence, so oldest set of children uses a relatively crude set of gestures. But younger generations have continued to refine them, forming a completely new language with its own grammatical rules.
The sum of its parts
Ann Senghas of Columbia University, New York, has been studying the group's signs each year since 1990. She believes the way the language has developed reveals some secrets about the way our brains are wired.
In her latest study, published in Science1, Senghas studied a property common to most spoken and sign languages around the world: that expressions are constructed from pieces with smaller meaning. For example, if we say a wheel is rolling down the hill, we use different words for 'rolling' and 'down', even though both are part of the same action. This provides us with a flexible vocabulary that can be mixed and matched to describe other events.
Senghas asked signers of different ages to tell a story and found that, by the second 'generation' of children, those speaking the newborn Nicaraguan language had a similar system. Rather than have one sign for 'rollingdown', which would be the most economical option, they had two separate gestures.
This suggests that children are born with a natural ability to break down language in this way. Hard wired rules like this help explain how language is acquired so easily.
"It's a dramatic demonstration of how un-learned this whole thing is," says Lila Gleitman who studies language acquisition at the University of Pennsylvania in Philadelphia.
It is not clear whether this ability to break concepts into parts is specific to language, or whether it might be part of a wider ability that could be applied to other learning tasks.
But the real beauty of the study, say linguists, is that it shows how children conjure and adapt language so quickly and from scratch. "You think it takes years and years of evolution, and then boom, one [language] emerges in a generation," says Senghas. "It's kind of amazing."
- Senghas A., Kita S. & Ozyurek A. Science, 305. 1779 - 1782 (2004).