Raise four fingers (the sign for “B”), touch your nose with your thumb and dip your hand down to mimic an elephant’s trunk. You’ve just said “Babar the elephant” in Nicaraguan Sign Language for the deaf – and it’s a sign that’s distinct from that for simply “elephant”.

It’s not surprising that ISN (for its initials in Spanish) is a language rich in children’s words, since it was children that developed it. Until the 1970s, there were no facilities or learning programmes for deaf children in Nicaragua, but with the Sandinista revolution came a new impetus to provide education for kids with special needs. Some four hundred deaf children were identified in the capital, Managua, and two schools created for them. The initiative could easily have back-fired, as teachers were brought from Europe who tried to teach Spanish using fingerspelling, which the kids couldn’t grasp because they’d never learned Spanish at home. Instead, each had their own signs used within their families, and in the classroom, the playground and the school bus they began to share them, eventually turning impromptu communication into a common language.

I learnt about ISN from Kath Owston, who’s from St Thomas’ Hospital and is on a three-year career break working with deaf children in the Nicaraguan city of Estelí. A journalist there called Famnuel Ubeda runs an arts and media project attended by around fifty young people who make a TV magazine show and give news broadcasts for the deaf. He also runs classes in ISN from his mother’s house. Neither project receives government help and he is looking for sponsorship to be able to continue. Kath has been learning ISN at his class, which runs for three hours on Sunday mornings, attended by 14 primary school teachers and a few parents. One is the mother of three-year old Shoskey, the child who showed Kath how to sign Babar the elephant. Brought up in a family with whom he could barely communicate, he now has hearing aids, bought by his parents with substantial help from an overseas donor. Shoskey loves using the aids, but to his family is making frustratingly slow progress in learning Spanish. It’s been Kath’s job to explain how much time it takes time to learn a language, while offering Shoskey as much help as she can, given that Spanish is not her first language.

ISN has grown from being the invention of a group of schoolchildren into an internationally recognised sign language. It might never have done so, as the teachers in the schools where it started weren’t able to understand it, much less appreciate how sophisticated it had become. So the education ministry turned for help to a US sign language expert, Judy Kegl, who in 1986 established that a structured language had indeed emerged, as the “pidgin” form that it took at the start among older students was eventually supplanted by grammar and verbs developed by the younger children. Steven Pinker, in The Language Instinct, said that ISN was like pantomime gestures being replaced by a language complex enough to be used in poetry, a life history, or to tell the plot of a surrealistic cartoon: “A language has been born before our eyes.”

It was a ten-year wait until the first ISN dictionary was published, helping the language to become more widespread, although lack of resources still prevents every deaf child from having their own copy. And it wasn’t until 2004 that interpreters were available, although in the last few years they’ve become more numerous and are seen on TV news channels and at official occasions, notably presidential speeches.

Given the environment in which it has developed, it’s not surprising that ISN has specific signs not just for international comic characters like Babar, but for key political personalities. These embody some typically Nicaraguan humour. The sign for President Daniel Ortega, for example, is one hand tapping the opposing wrist (where he always wears his Rolex watch). The late Fidel Castro, often referred to in political speeches, is signed by a bossy wagging of the finger combined with a V-sign moving away from the mouth, as in smoking a cigar.

The new sign for Donald Trump was first thought to be a gesture across the chest (indicating a presidential sash) followed by holding the nose. In the definitive version, the second part has become smoothing the hair down across the forehead from right to left. More diplomatic, perhaps. And maybe it’s better not to risk stirring Trump’s interest in Central America.

Anyone wishing to find out more about or contribute to the project in Esteli can contact Famnuel at Famnuel@gmail.com or Kathy at owstonlewis@hotmail.com

Original blog in Nicanotes and also in the London Review of Books.