[3][4][5][6][7][8] Particularly, an admixture between the Khvalynsk and Caucasian Copper Age burials gave rise to the ancestry that later became known as a typical marker (WSH – Western Steppe Herders) of the Yamnaya pastoralists.
[3][4][5][6][7] It also has been proposed by some to lend support to the Indo-Hittite hypothesis, according to which both proto-Anatolian and proto-Indo-European split-off from a common mother language "no later than the 4th millennium BCE.
"[29] They further note that this lends support to the Indo-Hittite hypothesis, according to which both proto-Anatolian and proto-Indo-European split-off from a common mother language "no later than the 4th millennium BCE.
"[30] However, Wang et al. also acknowledge that according to genetic evidence, an origin of the Proto-Indo-European language in the North Pontic/Caucasus region is possible, noting: latest ancient DNA results from South Asia suggest an LMBA spread via the steppe belt.
This scenario finds support from the well attested and widely documented ‘steppe ancestry’ in European populations and the postulate of increasingly patrilinear societies in the wake of these expansions.
[31]Kristian Kristiansen, in an interview with Der Spiegel in May 2018, stated that the Yamnaya culture may have had a predecessor at the Caucasus, where "proto-proto-Indo-European" was spoken.
[32] J. Grepin wrote in a review (1986) in the Times Literary Supplement the model of linguistic relationships is "the most complex, far reaching and fully supported of this century".
[34] Anthony cites evidence from ancient DNA, that the Bronze Age Maykop people of the Caucasus (previously proposed as a possible southern source of language and genetics at the root of Indo-European), had little genetic impact on the Yamnaya (whose paternal lineages differ from those found in Maykop remains, but are instead related to those of pre-Yamnaya Eastern European steppe hunter-gatherers).
Partly for these reasons, Anthony concludes that Bronze Age Caucasus groups such as the Maykop "played only a minor role, if any, in the formation of Yamnaya ancestry."