You probably know that much of the world’s environment is under threat. But a new study says languages are disappearing alongside plants and animals.

The study, from the World Wildlife Fund, measured the threat to languages using a scale that tracks how threatened species are. Not only are many languages steadily losing speakers, says co-author Jonathan Loh, but “the rate of decline, globally, is actually very close to the rate of decline in populations of wild vertebrate species.”

There’s the obvious threat of in-demand languages, which many people start speaking more and more as the speakers of smaller languages dwindle. “Thousands of indigenous languages spoken around the world are being replaced by one of a dozen or so dominant world languages like English, Spanish, Mandarin Chinese,” Loh says.

But Loh, who’s also a research associate at the Zoological Society of London, says that languages are dying off due to many of the same issues that plants and animals face.

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