Their observations show that children, not adults, are key
to the evolution and development of language, the researchers reported 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 1000 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 socialise. You meet deaf
people who are 50 and they really can't communicate," she said.

New language

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.

"We can really see how a new language emerges"

Psycholinguist Ann Senghas,
Columbia University

"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.     

"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.

More than gestures

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," Senghas said.

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," she 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."

Own rules

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."