Michael Krauss, a language researcher at the University of Alaska, warned that the rate at which native tongues were going would cause irreparable damage to human civilisation.
"Languages are being lost at an unbelievable and unprecedented rate which is almost the inverse of the population curve, which we know is going straight up. The loss-of-languages curve is going straight down."
At present between 20 and 50 per cent of the world's languages are no longer being learnt by children, he said. "For the next century something up to 95 per cent of mankind's languages will either become extinct or become moribund and headed towards extinction."
The pressures leading to language extinction stem from encroachment on the territories of indigenous peoples, mass migration and the desire to learn the dominant languages of the world, notably English. Even surviving languages are becoming more homogeneous as more prestigious dialects replace their less prestigious relatives.
"Why should we care? The first argument is that the world would be a less interesting place to live in," Dr Krauss said. The second argument is that "mankind's way of thinking in different ways is reduced". For instance, some medicinal plants are only known to certain native people, so cultural knowledge is lost with a language.
Dr Krauss identified medicinal plants such as curare and quinine that are unlikely to have come to prominence without understanding the South American languages that gave the plants their names. "You can imagine how many we don't know," he said.
"The last argument is that we do not yet realise that we are living in an eco-system of human diversity which is essential to our survival. Do we know what we are doing when we eliminate that diversity? We do not have the right to make that decision for posterity."
Lea Anne Hinton, a linguist from the University of California, said the loss of native languages had been especially acute in America. "There are still 50 native American languages being spoken in California but not a single one of them is spoken by children. The vast majority are spoken by less than 10 individuals over 70 years old."
Three weeks ago, Dr Hinton said, the Northern Pomo language, one of the 50 native languages of California, became extinct with the death of its last speaker. "This happens at least once a year where a Californian language goes extinct."
Dr Krauss said that it would be inconceivable for new languages to evolve at the rate at which old languages are being lost. "I cannot imagine that rediversification will do anything but slow down to practically nil and that we're not going to regenerate anything like the diversity we are losing."Reuse content