Sutherland William J
Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK.
Nature. 2003 May 15;423(6937):276-9. doi: 10.1038/nature01607.
There are global threats to biodiversity with current extinction rates well above background levels. Although less well publicized, numerous human languages have also become extinct, and others are threatened with extinction. However, estimates of the number of threatened languages vary considerably owing to the wide range of criteria used. For example, languages have been classified as threatened if the number of speakers is less than 100, 500, 1,000, 10,000, 20,000 or 100,000 (ref. 3). Here I show, by applying internationally agreed criteria for classifying species extinction risk, that languages are more threatened than birds or mammals. Rare languages are more likely to show evidence of decline than commoner ones. Areas with high language diversity also have high bird and mammal diversity and all three show similar relationships to area, latitude, area of forest and, for languages and birds, maximum altitude. The time of human settlement has little effect on current language diversity. Although similar factors explain the diversity of languages and biodiversity, the factors explaining extinction risk for birds and mammals (high altitude, high human densities and insularity) do not explain the numbers of endangered languages.
生物多样性面临着全球性威胁，当前的物种灭绝率远高于正常水平。尽管鲜为人知，但众多人类语言也已灭绝，还有其他语言也面临灭绝威胁。然而，由于所采用的标准范围广泛，对濒危语言数量的估计差异很大。例如，如果某种语言的使用者人数少于100、500、1000、10000、20000或100000，那么这种语言就被归类为濒危语言（参考文献3）。在此我表明，通过应用国际公认的物种灭绝风险分类标准，语言比鸟类或哺乳动物受到的威胁更大。珍稀语言比常见语言更有可能呈现出衰退迹象。语言多样性高的地区鸟类和哺乳动物的多样性也高，并且这三者与面积、纬度、森林面积以及（对于语言和鸟类而言）最高海拔都呈现出相似的关系。人类定居的时间对当前的语言多样性影响不大。尽管相似的因素解释了语言多样性和生物多样性，但解释鸟类和哺乳动物灭绝风险的因素（高海拔、高人口密度和岛屿性）并不能解释濒危语言的数量。
