AROUND a quarter of the world's population speaks just three languages: Mandarin, English and Spanish. But out of the 6,700 of the world's identified languages, nearly 2,500 are deemed at risk according to UNESCO, the UN's cultural body. The imposition of a colonial language long ago in big countries such as Brazil and America is still endangering the diversity of native tongues. In America, 53 languages have become extinct since 1950, more than in any other country.