Biologists using tools developed for drawing evolutionary family trees say that they have solved a longstanding problem in archaeology: the origin of the Indo-European family of languages.

The family includes English and most other European languages, as well as Persian, Hindi and many others. Despite the importance of the languages, specialists have long disagreed about their origin.

Linguists believe that the first speakers of the mother tongue, known as proto-Indo-European, were chariot-driving pastoralists who burst out of their homeland on the steppes above the Black Sea about 4,000 years ago and conquered Europe and Asia. A rival theory holds that, to the contrary, the first Indo-European speakers were peaceable farmers in Anatolia, now Turkey, about 9,000 years ago, who disseminated their language by the hoe, not the sword....