There are about 7,000 recognised languages worldwide, but many of them could soon be lost forever.
According to a study from Australia, about half of all languages are endangered, and 1,500 could be extinct by the end of the century.
"Without intervention, language loss could triple within 40 years, with at least one language lost per month," the authors write. They advise creating curricula that support bilingual education and encourage both indigenous language mastery and the use of regionally dominant languages.
Fifty-one independent variables were analysed, including education policy, socioeconomic indicators and environmental characteristics.
The study, led by the Australian National University (ANU), was published in the online journal Nature Ecology and Evolution.
The research also uncovered unexpected and surprising causes of language threat, said co-author Lindell Bromham. These include a well-developed road network, for example, he said.
"(We) found that the more roads there are, connecting country to city, and villages to towns, the higher the risk of languages being endangered. It's as if roads are helping dominant languages 'steamroll' over other smaller languages," Bromham said.
Contact with other local languages, on the other hand, is not the problem: in fact, languages that come into contact with many other indigenous languages are less at risk.
The study also contains lessons for the preservation of endangered Indigenous Australian languages.
"Australia has the dubious distinction of having one of the highest rates of language loss worldwide," said co-author Felicity Meakins. Of the 250 languages once spoken by Indigenous people, she said, only 40 remain – and children learn only a dozen of them in the first place.
"When a language is lost, or is 'sleeping' as we say for languages that are no longer spoken, we lose so much of our human cultural diversity," Bromham pointed out. "Every language is brilliant in its own way."
Many of the languages that are expected to be lost this century are still actively used at present, the expert said.
"So there is still the chance to invest in supporting communities to revitalize indigenous languages and keep them strong for future generations," he said, referring to the upcoming Unesco Decade of Indigenous Languages (2022-32).
With the initiative, the United Nations wants to protect linguistic diversity around the globe and strengthen the rights of people from language minorities. – dpa