The genetic origin of the Indo-Europeans

Abstract

The Yamnaya archaeological complex appeared around 3300 BCE across the steppes north of the Black and Caspian Seas, and by 3000 BCE reached its maximal extent from Hungary in the west to Kazakhstan in the east. To localize Yamnaya origins among preceding Eneolithic people, we assembled ancient DNA from 428 individuals, demonstrating three genetic clines. A “Caucasus-Lower Volga” (CLV) Cline suffused with Caucasus hunter-gatherer1 ancestry extended between a Caucasus Neolithic southern end, and a northern end at Berezhnovka along the Lower Volga river. Bidirectional gene flow created intermediate populations, such as north Caucasus Maikop people, and those at Remontnoye on the steppe. The “Volga Cline” was formed as CLV people mixed with upriver populations of Eastern hunter-gatherer2 ancestry, creating hyper-variable groups as at Khvalynsk. The “Dnipro Cline” was formed as CLV people moved west, mixing with Ukraine Neolithic hunter-gatherers3 along the Dnipro river to establish Serednii Stih groups from whom Yamnaya ancestors formed around 4000 BCE and grew explosively after 3750–3350 BCE. CLV people contributed four-fifths of the ancestry of the Yamnaya, and, entering Anatolia likely from the east, at least a tenth of the ancestry of Bronze Age Central Anatolians, where Hittite was spoken4,5. We thus propose that the final unity of the speakers of “Proto-Indo-Anatolian”, the language ancestral to both Anatolian and Indo-European, was among CLV people sometime between 4400–4000 BCE.