How did deaf children in Nicaragua invent a brand-new language?

Deaf children in Nicaragua invented a language simply by being brought together. Before the late 1970s, deaf Nicaraguans were isolated, each communicating with family through simple home-made gestures. Then, from 1977, new schools gathered hundreds of deaf children in Managua. The teachers tried to teach spoken Spanish and lipreading, and it largely failed. But in the schoolyard, on the street and on the school bus, the children pooled their gestures and home signs, and a new language quickly took shape.

The teachers did not realize it. They saw mime and a failure to learn Spanish, and in 1986 they called in Judy Kegl, an American sign language linguist. She and other researchers found something remarkable: the younger children, who arrived later, had not just learned the older children's signing, they had made it richer, adding grammar such as verb agreement. The children were changing the language as they learned it.

That is why Nicaraguan Sign Language is famous among scientists. Unlike creoles, which grow from communities of fluent speakers, it came from kids with only scraps of gesture. Steven Pinker, author of The Language Instinct, called it the only time we have seen a language created out of thin air. Some see it as proof that the brain is wired for language; others dispute that, and the debate continues.