Ever since British jurist Sir William Jones noted in 1786 that there are marked similarities between diverse languages such as Greek, Sanskrit, and Celtic, linguists have assumed that most of the languages of Europe and the Indian subcontinent derive from a single ancient tongue. But researchers have fiercely debated just when and where this mother tongue was first spoken. Now a bold new study asserts that the common root of the 144 so-called Indo-European languages, which also include English and all the Germanic, Slavic, and Romance languages, is very ancient indeed. In this week's issue of Nature, evolutionary biologist Russell...