Nicaraguan Sign Language
Idioma de Signos Nicaragüense, or Nicaraguan Sign Language, is a sign language that was spontaneously invented by deaf schoolchildren in Nicaragua in the 1970s and 1980s.  The language developed when the Sandinist government of Nicaragua created the first (elementary) school for deaf people, in the 1970s. The language is of special interest to linguists, because it allows them to study how languages develop.