Western Steppe Herders

In archaeogenetics, the term Western Steppe Herders (WSH), or Western Steppe Pastoralists, is the name given to a distinct ancestral component first identified in individuals from the Chalcolithic steppe around the turn of the 5th millennium BC, subsequently detected in several genetically similar or directly related ancient populations including the Khvalynsk, Repin, Sredny Stog, and Yamnaya cultures, and found in substantial levels in contemporary European, Central Asian, South Asian and West Asian populations.

[7][8][9] Around 3,000 BC, people of the Yamnaya culture or a closely related group,[2] who had high levels of WSH ancestry with some additional Neolithic farmer admixture,[5][10] embarked on a massive expansion throughout Eurasia, which is considered to be associated with the dispersal of at least some of the Indo-European languages by most contemporary linguists, archaeologists, and geneticists.

[15][16][17] A summary of several genetic studies published in Nature and Cell during the year 2015 is given by Heyd (2017): 'Steppe ancestry' can be classified into at least three distinctive clusters.

In its simplest and earliest form, it can be modelled as an admixture of two highly divergent ancestral components; a population related to Eastern Hunter-Gatherers (EHG) as the original inhabitants of the European steppe in the Mesolithic, and a population related to Caucasus Hunter-Gatherers (CHG) that had spread northwards from the Near East.

[22][10] The precise location of the initial formation of so-called 'Eneolithic steppe' ancestry, which can be modeled as a relatively simple admixture of EHG and Near Eastern (CHG-related) populations, remains uncertain.

[4][10] Admixture between populations with Near Eastern ancestry and the EHG on the Pontic-Caspian steppe had begun by the fifth millennium BC, predating the Yamnaya culture by at least 1,000 years.

[5][26] Archaeologist David Anthony speculates that the Khvalynsk/Progress-2 mating network, located between the middle Volga and the North Caucasus foothills, makes a "plausible genetic ancestor for Yamnaya".

[10] Genetic evidence demonstrates a major and relatively sudden population turnover in Europe during the early third millennium BC, resulting in the rapid spread of steppe ancestry along with the Corded Ware and Bell Beaker cultures.

[2][9] Corded Ware individuals have been shown to be genetically distinct from preceding European Neolithic cultures of North-Central and Northeastern Europe, with around 75% of their ancestry derived from a Yamnaya-like population.

[9] A 2021 study suggests that Early Corded Ware from Bohemia can be modelled as a three way mixture of Yamnaya-like and European Neolithic-like populations, with an additional c. 5% to 15% contribution from a northeast European Eneolithic forest-steppe group (such as Pitted Ware, Latvia Middle Neolithic, Ukraine Neolithic, or a genetically similar population), a cluster the authors term 'Forest Steppe' ancestry.

[9] In the Bell Beaker culture, high proportions (c. 50%) of steppe related ancestry are found in individuals from Germany, the Czech Republic, and Britain.

Individuals from the Sintashta, Andronovo, and Srubnaya cultures are all genetically similar and may ultimately descend from a secondary migration of the Fatyanovo population, an eastern Corded Ware group.

It has been suggested that the Central Steppe MLBA cluster was the main vector for the spread of Yamnaya-related ancestry to South Asia in the early 2nd millennium BC.

Anthony cites this as additional evidence that the Indo-European languages were initially spoken among EHGs living in Eastern Europe.

[28] Geneticist David Reich concludes that the massive migration of Western Steppe Herders probably brought this mutation to Europe, explaining why there are hundreds of millions of copies of this SNP in modern Europeans.

"[44] In one study, five ancient DNA samples from Yamnaya sites had a frequency of over 25% of an allele that is associated with lactase persistence, conferring lactose tolerance into adulthood.

Main genetic ancestries of Western Steppe Herders (Yamnaya pastoralists): a confluence of Eastern Hunter-Gatherers (EHG) and Caucasus Hunter-Gatherers (CHG). [ 1 ]
Scheme of Indo-European migrations from c. 4000 to 1000 BC according to the widely held Kurgan hypothesis . These migrations are thought to have spread WSH ancestry and Indo-European languages throughout large parts of Eurasia. [ 2 ] [ 3 ] [ 4 ]
Migration of Yamnaya-related people, according to Anthony (2007), [ 18 ] (2017); [ 19 ] Narasimhan et al. (2019); [ 4 ] Nordqvist & Heyd (2020): [ 20 ]
Admixture proportions of Yamnaya populations. They combined Eastern Hunter Gatherer ( EHG), Caucasian Hunter-Gatherer ( CHG), Anatolian Neolithic ( ) and Western Hunter Gatherer ( WHG) ancestry. [ 21 ]
Scheme of Indo-European migrations from c. 3000 to 800 BC
The eastern part of the Corded Ware culture contributed to the Sintashta culture (c. 2100–1800 BC), where the Indo-Iranian languages and culture emerged.
Archaeogenetic analysis of human skin pigmentation in populations across prehistoric Europe