Highly read on www.pnas.org in May

An analysis of a global data set tracking the geographical extent of some 6,900 languages has revealed that highly biodiverse areas accounting for 24% of Earth's land surface contain about 70% of the world's languages.

Biologists and linguists have previously noted that areas with high species diversity also tend to show high language diversity. The data set, published in 2010, has enabled Larry Gorenflo at Pennsylvania State University in University Park and his colleagues to perform a more detailed analysis. Regions that are particularly rich linguistically include parts of west Africa and southeast Asia and some of the Indonesian islands, which have more than 250 native languages each. These languages are often unique to their regions and many are at risk of extinction.

The authors suggest a range of possible reasons for this link. For one, the spread of a few dominant European languages tended to occur in more temperate areas, and not in the biodiverse tropics.

Proc. Natl Acad. Sci. USA 109, 8032–8037 (2012)