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 start 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 populations of Europe, Central Asia, South Asia and West Asia. This ancestry is often referred to as Yamnaya ancestry, Yamnaya-related ancestry, Steppe ancestry, or Steppe-related ancestry.

Western Steppe Herders are considered to be descended from a merger between Eastern Hunter-Gatherers (EHGs) and Caucasus Hunter-Gatherers (CHGs). The WSH component is modeled as an admixture of EHG and CHG ancestral components in roughly equal proportions, with the majority of the Y-DNA haplogroup contribution from EHG males. The Y-DNA haplogroups of Western Steppe Herder males are not uniform, with the Yamnaya culture individuals mainly belonging to R1b-Z2103 with a minority of I2a2, the earlier Khvalynsk culture also with mainly R1b but also some R1a, Q1a, J, and I2a2, and the later, high WSH ancestry Corded Ware culture individuals mainly belonging to haplogroup R1b in the earliest samples, with R1a-M417 becoming predominant over time.

Around 3,000 BC, people of the Yamnaya culture or a closely related group, who had high levels of WSH ancestry with some additional Neolithic farmer admixture, 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. WSH ancestry from this period is often referred to as Steppe Early and Middle Bronze Age (Steppe EMBA) ancestry.

This migration is linked to the origin of both the Corded Ware culture, whose members were of about 75% WSH ancestry, and the Bell Beaker ("Eastern group"), who were around 50% WSH ancestry, though the exact relationships between these groups remains uncertain.

The expansion of WSHs resulted in the virtual disappearance of the Y-DNA of Early European Farmers (EEFs) from the European gene pool, significantly altering the cultural and genetic landscape of Europe. During the Bronze Age, Corded Ware people with admixture from Central Europe remigrated onto the steppe, forming the Sintashta culture and a type of WSH ancestry often referred to as Steppe Middle and Late Bronze Age (Steppe MLBA) or Sintashta-related ancestry.

The modern population of Europe can largely be modeled as a mixture of WHG (Western Hunter-Gatherers), EEF (Early European Farmers), and WSH (Western Steppe Herders), with proportions varying among different Indo-European groups such as Balts, Slavs, Germanics, and others. Contemporary Indo-Aryans of South Asia, especially upper caste populations, can largely be modeled as a mix of Bronze Age_Steppe and Indus Periphery (Iranian hunter-gatherer and AASI) ancestry, with proportions varying among different communities. In contrast, non-Indo-European South Asian Dravidian populations show significant extra AASI (Ancient Ancestral South Indian) and Indus Periphery ancestry also, with relatively less Steppe contribution.

WSH ancestry peaks in Northern Europe, particularly among Irish people, Norwegians, Swedes, Belarusians, Lithuanians, Scots and Icelanders. In South Asia, WSH ancestry reaches its highest levels in the northern Indian subcontinent, especially among Brahmin, Bhumihar, Ror, Jat, and Kalash. Modern-day south-central Asians, particularly the Yaghnobis and Tajiks, both Eastern Iranian peoples, exhibit strong genetic continuity with Iron Age Central Asians (Indo-Iranians). They may serve as proxies for the source of "Steppe ancestry" found among many Central Asian and Middle Eastern (or West Asian) groups, who also carry a significant BMAC (Bactria–Margiana Archaeological Complex) genetic component.