New research shows economic growth to be main driver of language extinction and reveals global 'hotspots' where languages are most under threat.
The study's authors urge for "immediate attention" to be paid to hotspots in the most developed countries - such as north Australia and the north-western corners of the US and Canada - where conservation efforts should be focused.
They also point to areas of the tropics and Himalayan regions that are undergoing rapid economic growth as future hotspots for language extinction, such as Brazil and Nepal.
The study is published today in the journal Proceedings of Royal Society B.
The researchers used the criteria for defining endangered species to measure rate and prevalence of language loss, as defined by the International Union for Conservation of Nature.
The three main risk components are: small population size (small number of speakers), small geographical habitat range and population change - in this case, the decline in speaker numbers.
By interrogating huge language datasets using these conservation mechanisms, the researchers found that levels of GDP (Gross Domestic Product) per capita correlated with the loss of language diversity: the more successful economically, the more rapidly language diversity was disappearing.
"As economies develop, one language often comes to dominate a nation's political and educational spheres. People are forced to adopt the dominant language or risked being left out in the cold - economically and politically," said Dr Tatsuya Amato, from the University of Cambridge's Department of Zoology.
"Of course everyone has the right to choose the language they speak, but preserving dying language is important to maintaining human cultural diversity in an increasingly globalised world."
In the northwest corner of North America, the languages of the indigenous people are disappearing at an alarming rate. Upper Tanana, for example, a language spoken by indigenous Athabaskan people in eastern Alaska, had only 24 active speakers as of 2009, and was no longer being acquired by children. The Wichita language of the Plains Indians, now based in Oklahoma, had just one fluent speaker as of 2008.
In Australia, aboriginal languages such as the recently extinct Margu and almost extinct Rembarunga are increasingly disappearing from the peninsulas of the Northern Territories.
As the researchers point out, "languages are now rapidly being lost at a rate of extinction exceeding the well-known catastrophic loss of biodiversity". Major international organisations such as the United Nations and Worldwide Fund for Nature are now actively engaged in the conservation of linguistic diversity.
Amano says the global meta-analysis produced by the team using the species criteria is designed to complement the more specific, localised examples featured in many linguistic and anthropological research.
Unlike species extinction, however, language diversity has a potentially saving grace - bilingualism. Previous research from Cambridge's Department of Theoretical and Applied Linguistics has shown that children who speak more than one language have multiple advantages in education, cognition and social interaction.
"As economies develop, there is increasing advantage in learning international languages such as English, but people can still speak their historically traditional languages. Encouraging those bilingualisms will be critical to preserving linguistic diversity," added Amano.