At a school in Managua, Nicaragua, deaf children are speaking a new language entirely their own, which nonetheless has remarkable similarities to the world's other languages. Researchers studying these similarities suggest this week in Science that, in fact, children give language its most fundamental, universal features just by the way they learn it.
As varied as they may sound to the untrained ear, all languages share certain basic traits that have been the subject of debate for decades.
While some researchers have argued that these traits come hard-wired in the human brain, others have argued that they developed gradually over generations through experimentation and improvement. In contrast, the new study suggests that the source of these similarities is the way languages are learned.
Ann Senghas of Barnard College of Columbia University and her colleagues propose that even if children aren't born with a "blueprint" for language (as Noam Chomsky, for example, has argued), their brains do use a specific approach to learning that can turn a simple communication system into a true language in a surprisingly short period of time.
The researchers compared the ways that deaf children and adults used Nicaraguan Sign Language (NSL) to tell a story. The signers had learned the language at different stages of its brief history.
While the oldest signers described actions using pantomime-like gestures, the younger generations carved the gestures into simpler, basic words, following rules fundamental to all languages.
The authors suggest that as subsequent groups of children have learned NSL, they have, all on their own, turned what was once more like gesture into a true language. Their study appears in the 17 September 2004 issue of the journal Science, published by AAAS, the nonprofit science society.
"We're seeing evolution in action, but what's evolving here isn't an organism. It's a language system," Senghas said.
"Languages essentially 'reproduce' when they are passed from one mind to the next -- that is, when they are learned by a new child. That means the moment of learning is potentially a very powerful moment, an opportunity for shaping and restructuring," she said.
But is it powerful enough to create a whole new language from raw materials such as gestures? According to Senghas and her colleagues, the Nicaraguan case shows that it is.
Senghas' coauthors are Sotaro Kita of the University of Bristol in England and Aslý Özyürek of Nijmegen University and Max Planck Institute for Psycholinguistics in Nijmegen, The Netherlands and of Koç University in Istanbul, Turkey.
Before the 1970s, most deaf people in Nicaragua stayed at home and had little contact with each other, according to Senghas. The government expanded opportunities for special education with a new elementary school in Managua in 1977 and a vocational school in 1981.
Approximately 50 deaf students enrolled the first year, and the number grew to over 200 by 1981. No one taught the children to sign, but as soon as they were together they began to develop a system of gestures for communicating with each other, both in and out of school. Today there are approximately 800 deaf signers of NSL, ranging from four to 45 years old.
Each wave of children that enters the community develops NSL further, making it more complex and versatile, and signing with greater speed and fluidity.
"It's an unusual community, sort of upside-down, in the sense that the children lead the way. The children are the most fluent users of the language, not the older adults," Senghas said.
The researchers studied a trait central to all developed languages called "discreteness," meaning that information is packaged into separate elements that can be put together according to various rules. For example, no matter what the language, it consists of words, which combine to make sentences.
Expressions of motion are particularly useful for studying discreteness in spoken and signed languages. In developed languages we break up the idea of a continuous movement into separate words. For example, in the expression, "rolling down the hill," one word ("rolling") conveys the type of movement while another ("down") conveys the direction.
In contrast, a typical gesture describing "rolling down a hill" would be a single, unbroken movement of the hand, such as a circular motion along a downward path.
Senghas and her colleagues studied deaf individuals from each of the three age-groups that use NSL and hearing individuals who speak Spanish. They showed each participant a cartoon in which a cat swallows a bowling ball and then wobbles down a steep road. Then, they asked the participants to tell the story in their language.
The signing of the oldest group looked much like the gestures produced by the hearing group as they spoke, combining movement type and direction in a single hand motion.
The two younger groups, however, separated the movement type and direction into different signs, as is done in spoken language.
"So what they're doing looks very language-like and does not look gesture-like, even though they're taking gestures to make the language. And that tells me there's something really core about that drive," Senghas said.
Even without being taught, children automatically seek out rules of language such as discreteness to communicate, according to Senghas.
"Everything surrounding the children is telling them that manner and path belong together -- they happen together in the event, and they happen together in the gestures speakers make. But, the children go against everything they're seeing, in favor of something that takes more effort -- they separate manner and path into independent elements. And it so happens that this is what we see in language after language," Senghas said.
Thus, parents may not need to worry too much about teaching children to talk by a certain age or using special tools like flashcards or vocabulary drills, she said. All they need is natural social interaction.
"Kids have their radar out from the beginning; they're looking for language-like information in the world. And they're ready to process that information in a specific way. You don't need to teach children language any more than you need to teach them to walk," Senghas said.