Many people know about the threatened polar bear and extinct passenger pigeon, but few have heard of endangered and extinct languages such as Eyak in Alaska, whose last speaker died in 2008, or Ubykh in Turkey, whose last fluent speaker died in 1992, says Tatsuya Amano, a zoologist at the University of Cambridge in the United Kingdom and lead author of the new study. Two types of language loss hotspots emerged from the study, published online today in the Proceedings of the Royal Society B. People are forced to adopt the dominant language or risk being left out in the cold - economically and politically Tatsuya Amano, University of Cambridge 
 
 The researchers found that the more successful a country was economically, the more rapidly its languages were being lost.
– There are some 6,909 languages spoken today, but many are on the decline, and the biggest reason, researchers find, is economic growth. Researchers studied the 649 languages for which growth and decline data was available to determine the leading factors driving the change, Science magazine reports. In order to reach their conclusions, they turned to methods typically employed to track endangered animal populations; interestingly, the study's lead author, Tatsuya Amano, is a zoologist. His team examined the relationships between a language's disappearance and a country's GDP, altitude, and other possible influences. Economic growth showed the strongest correlation to the fading of a language. "As economies develop, one language often comes to dominate a nation's political and educational spheres," Amano says, as per the BBC. "People are forced to adopt the dominant language or risk being left out in the cold—economically and politically." A quarter of the world's languages may be in danger, he notes; fewer than 25 people currently speak Upper Tanana in Alaska, for instance. (Meanwhile, the English language keeps growing.)