The following is based on an article published in 2012.

Most linguists believe proto-Indo-European, the ancestor of all Indo-European

languages, was the language of chariot-driving pastoralists who spread through

Eurasia from steppes north of the Black Sea about 4,000 years ago. But a

competing theory is that proto-Indo-European was spoken by farmers in Anatolia

(Asia Minor) about 9,000 years ago, and spread from there along with agriculture.

To evaluate these hypotheses, researchers statistically compared IndoEuropean languages’ vocabularies. Languages with more similar vocabularies are

probably more closely related, sharing more recent common ancestors.

Combining the vocabulary statistics with the known dates when certain languages

split, and with their known geographical ranges, a computer calculated the most

likely relationships among all Indo-European languages and concluded that protoIndo-European probably originated in Anatolia 9,000 years ago.

Disputing this conclusion, skeptics argue that most Indo-European languages

are similar in their words pertaining to chariots and wagons, suggesting protoIndo-European split into daughter languages only after chariots and wagons were

invented. No archaeological evidence indicates that chariots and wagons existed

before 5,500 years ago. Furthermore, proto-Indo-European had words for "horse"

and "bee" and lent many words to proto-Uralic, the mother language of Finnish

and Hungarian. The steppes north of the Black Sea were far closer than Anatolia

to areas where proto-Uralic was spoken, and had more abundant wild horses and

bees.