New insights into the origin of Indo-European languages have been published in a study in the journal Science.
Two main theories are known to have dominated the origins debate - the 'Steppe' hypothesis and the 'Anatolian' or 'farming' hypothesis.
The Steppe hypothesis proposes the origin to be in the Pontic-Caspian Steppe around 6000 years ago, while the farming one suggests an older origin tied to early agriculture around 9000 years ago.
Previous evolutionary analyses of Indo-European languages have come to conflicting conclusions about the age of the family, due to the combined effects of inaccuracies and inconsistencies in the datasets they used and limitations in the way that phylogenetic methods analyzed ancient languages.
Researchers at the Max Planck Institute for Evolutionary Anthropology, Germany, used recently developed ancestry-enabled Bayesian phylogenetic analysis to test whether ancient written languages, such as Classical Latin and Vedic Sanskrit, were the direct ancestors of modern Romance and Indic languages, respectively.
"Our chronology is robust across a wide range of alternative phylogenetic models and sensitivity analyses," said Russell Gray, senior author of the study.
Estimating the Indo-European family to be approximately 8100 years old, with five main branches already split off by around 7000 years ago, the analyses' results agreed entirely with neither the Steppe nor the Anatolian hypotheses.
"Recent ancient DNA data suggest that the Anatolian branch of Indo-European did not emerge from the Steppe, but from further south, in or near the northern arc of the Fertile Crescent as the earliest source of the Indo-European family. Our language family tree topology, and our lineage split dates, point to other early branches that may also have spread directly from there, not through the Steppe," said the study's first author, Paul Heggarty.
The study authors have now proposed a new hybrid hypothesis for the origin of the Indo-European languages, with an ultimate homeland south of the Caucasus and a subsequent branch northwards onto the Steppe, as a secondary homeland for some branches of Indo-European entering Europe with the later Yamnaya and Corded Ware-associated expansions.
"Ancient DNA and language phylogenetics thus combine to suggest that the resolution to the 200-year-old Indo-European enigma lies in a hybrid of the farming and Steppe hypotheses," said Gray.