Languages evolve in a similar way to biological organisms, with ancestral languages splitting into descendent ones. In language evolution, 'lexical borrowing', whereby a word is transferred from one language to another, is also common. Linguists have struggled to distinguish between words that have descended and those that have been borrowed.

Tal Dagan at the Heinrich Heine University in Düsseldorf, Germany, and her colleagues looked for instances of borrowing by analysing the relationships between 2,346 words of basic vocabulary with similar meanings from 84 Indo–European languages. By studying networks of related words, the researchers found that, on average, 8% of the basic vocabulary in each of the languages is borrowed. Basic vocabulary was previously assumed to be fairly immune to borrowing.

Proc. R. Soc. B doi: 10.1098/rspb.2010.1917 (2010)