WASHINGTON (Reuters) -- Deaf children thrown together in a school in Nicaragua without any type of formal instruction invented their own sign language -- a sophisticated system that has evolved and grown, researchers reported on Friday.
Their observations show that children, not adults, are key to the evolution and development of language, the researchers report in Friday's issue of the journal Science.
"It is the birth of a language," said Ann Senghas of Columbia University's Barnard College, who led the study.
The living laboratory of up to 1,000 children at a school in Managua was made possible because of the neglect of deaf people before the 1970s, a time of political and social turmoil in Nicaragua.
Deaf children were isolated and almost never learned formal sign language, Senghas and her international team of collaborators said.
"They didn't let them go out and socialize. You meet deaf people who are 50 and they really can't communicate," Senghas said.
But in 1977, a school for special education opened in Managua, followed four years later by a vocational school. For the first time, deaf children could meet and learn together, and could stay together as they grew up.
No one was there to teach them formal sign language, so they made up their own.
"The founding cohort of children started out with gesture," Senghas, a psycholinguist, said in a telephone interview.
Her team reports specifically on how the children described motion -- in one case, a ball rolling down a hill.
"They were doing rolling-down movement (with their hands), but what happened was that children who were around in the early '80s looked at that and took as input but produced something very different," Senghas said.
Building blocks of language
"They broke it down into these little elements like a roll element and a down element and an up element."
In spoken languages these elements can be words, or smaller modifiers of words, tones or even word order. They are the building blocks of language.
In the sign language, they were hand motions, but far different from mere gestures.
"They broke it down into bricks and they ended up with elements that you never see alone with gesture. They could assemble these into an infinite number of elements. They had a language."
The founding children, now adults in their 30s, have a different version of the sign language than the younger members of the community.
"They are a living record of the earlier stages of the language," Senghas said.
"It is the first time anyone has been able to study a language this early. We can really see how a new language emerges."
And, it seems, it is children who drive the evolution of language. "It is the child learners who are injecting the learning, the structure, into the language," Senghas said.
This process can be seen to a degree when a small child learns to talk and "breaks" the rules of grammar.
"She'll start out trying to make her own rules and as she ages she'll become more like people in her environment," Senghas said.
"By the time she is an adult, she'll talk a lot like you. But not exactly like you."
