The Yamnaya Steppe Herders from Russia

Discussion
For Europe, ancient genomics have revealed extensive population migrations, replacements, and admixtures from the Upper Paleolithic to the Bronze Age (1, 2, 27, 64, 65), with a strong influence across the continent from the Early Bronze Age (~3000–2500 BCE) western steppe Yamnaya. In contrast, for Central Asia, continuity is observed from the Upper Paleolithic to the end of the Copper Age (~3500–3000 BCE), with descendants of Paleolithic hunter-gatherers persisting as largely isolated populations after the Yamnaya and Afanasievo pastoralist migrations. Instead of western pastoralists admixing with or replacing local groups, we see groups with East Asian ancestry replacing ANE populations in the Lake Baikal region. Thus, unlike in Europe, the hunter/gathering/herding groups of Inner Asia were much less impacted by the Yamnaya and Afanasievo expansion. This may be due to the rise of early horse husbandry, likely initially originated through a local “prey route” (40) adaptation by horse-dependent hunter-gatherers at Botai. Since work on ancient horse genomes (32) indicates that Botai horses were not the main source of modern domesticates, this suggests the existence of a second center of domestication, but whether this second center was associated with the Yamnaya and Afanasievo cultures remains uncertain in the absence of horse genetic data from their sites.

Our finding that the Copper Age (~3300 BCE) Namazga-related population from the borderlands between Central and South Asia contains both “Iran Neolithic” and EHG ancestry but not CHG-specific ancestry provides a solution to problems concerning the Western Eurasian genetic contribution to South Asians. Rather than invoking varying degrees of relative contribution of “Iran Neolithic” and Yamnaya ancestries, we explain the two western genetic components with two separate admixture events. The first event, potentially prior to the Bronze Age, spread from a non-IE-speaking farming population from the Namazga culture or a related source down to Southern India. Then the second came during the Late Bronze Age (~2300–1200 BCE) through established contacts between pastoral steppe nomads and the Indus Valley, bringing European Neolithic as well as CHG-specific ancestry, and with them Indo-Iranian languages into northern South Asia. This is consistent with a long-range South Eurasian trade network around 2000 BCE (4), shared mythologies with steppe-influenced cultures (41, 60), linguistic relationships between Indic spoken in South Asia, and written records from Western Asia from the first half of the 18th century BCE onwards (49, 52).

In Anatolia, our samples do not genetically distinguish Hittite and other Bronze Age Anatolians from an earlier Copper Age sample (~3943-3708 BCE). All these samples contain a similar level of CHG ancestry but no EHG ancestry. This is consistent with Anatolian / Early European farmer ancestry, but not steppe ancestry, in the Copper Age Balkans (67) and implies that the Anatolian clade of IE languages did not derive from a large-scale Copper Age / Early Bronze Age population movement from the steppe (contra (4)). Our findings are thus consistent with historical models of cultural hybridity and “Middle Ground” in a multi-cultural and multi-lingual but genetically homogenous Bronze Age Anatolia (68, 69).

Current linguistic estimations converge on dating the Proto-Anatolian split from residual PIE to the late 5th or early 4th millennia BCE (58, 70) and place the breakup of Anatolian IE inside Turkey prior to the mid-3rd millennium (53, 71, 72). In (49) we present new onomastic material (51) that pushes the period of Proto-Anatolian linguistic unity even further back in time. We cannot at this point reject a scenario in which the introduction of the Anatolian IE languages into Anatolia was coupled with the CHG-derived admixture prior to 3700 BCE, but note that this is contrary to the standard view that PIE arose in the steppe north of the Caucasus (4) and that CHG ancestry is also associated with several non-IE-speaking groups, historical and current. Indeed, our data are also consistent with the first speakers of Anatolian IE coming to the region by way of commercial contacts and small-scale movement during the Bronze Age. Among comparative linguists, a Balkan route for the introduction of Anatolian IE is generally considered more likely than a passage through the Caucasus, due, for example, to greater Anatolian IE presence and language diversity in the west (73). Further discussion of these options is given in the archaeological and linguistic supplementary discussions (48, 49).

Thus, while the “Steppe hypothesis,” in the light of ancient genomics, has so far successfully explained the origin and dispersal of IE languages and culture in Europe, we find that several elements must be re-interpreted to account for Asia. First, we show that the earliest unambiguous example of horse herding emerged amongst hunter-gatherers, who had no significant genetic interaction with western steppe herders. Second, we demonstrate that the Anatolian IE language branch, including Hittite, did not derive from a substantial steppe migration into Anatolia. And third, we conclude that Early Bronze Age steppe pastoralists did not migrate into South Asia but that genetic evidence fits better with the Indo-Iranian IE languages being brought to the region by descendants of Late Bronze Age steppe pastoralists.

​Supplementary Materials
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www.ncbi.nlm.nih.gov/pmc/articles/PMC6748862/bin/EMS84309-supplement-Supplementary_Materials.docx

First bioanthropological evidence for Yamnaya horsemanship

Abstract
The origins of horseback riding remain elusive. Scientific studies show that horses were kept for their milk ~3500 to 3000 BCE, widely accepted as indicating domestication. However, this does not confirm them to be ridden. Equipment used by early riders is rarely preserved, and the reliability of equine dental and mandibular pathologies remains contested. However, horsemanship has two interacting components: the horse as mount and the human as rider. Alterations associated with riding in human skeletons therefore possibly provide the best source of information. Here, we report five Yamnaya individuals well-dated to 3021 to 2501 calibrated BCE from kurgans in Romania, Bulgaria, and Hungary, displaying changes in bone morphology and distinct pathologies associated with horseback riding. These are the oldest humans identified as riders so far.

INTRODUCTION
Multidisciplinary sources of evidence for earliest horsemanship
Using horses for transport was a decisive step in human cultural development. Trade and cultural exchange as well as conflicts and migrations leapt with the increase in speed and range provided by horsemanship. Archeological, archeozoological, and paleogenetic research into the beginnings of horse domestication and the initial expansion of domesticated horses (Equus caballus) has recently seen much progress (1, 2), as has our understanding of the appearance of horse-drawn fast chariots with spoked wheels ~2000 BCE (3).
However, information for earliest horseback riding so far is sparse (see section S1 for a detailed review). Possible bit wear in premolar teeth of horses from Botai (Kazakhstan) dating to <3500 BCE were extensively debated during the past three decades (4–6). Information from the Botai site such as horse demography, horse dung finds, potential paddock fences, or horse milk traces in pot shards (7, 8), as well as horse milk peptides in the calculus of Yamnaya individuals from Krivyanskiy 9 (Russia; ~3000 BCE) (9), suggests that domestication became widely established during the second half of the fourth millennium BCE. However, these do not provide direct evidence for riding.
Depictions from the Mesopotamian Ur III period shortly before 2000 BCE may be the earliest figurative evidence for riding, probably on a horse (rider seated forward, falling mane, and bushy tail hair) but possibly on an ass (Equus asinus) or ass-onager (Equus hemionus) hybrid (10). During the Old Babylonian period of the early second millennium BCE, indubitable images and literary mentions in cuneiform texts (11) prove that horses were ridden. However, it is apparent that organized cavalry was introduced not before the very end of the second millennium BCE (4).
While this provides a rough time frame and geographical setting, our understanding of how horsemanship developed between mid-fourth and early second millennium BCE in the Pontic-Caspian steppe and the Middle East is still vague. This time span also sees the first horse dispersals to the west and south (1, 2, 10, 12), the origins of modern horse breeds (1), the widespread introduction of cattle-pulled wheeled carts and wagons (13), and the Yamnaya (~3200 to 2500 BCE) expansions eastward to the Altai and Mongolia in the form of the Afanasievo culture (14) and westward into the southeast of Europe, coming to a hold at the Tisza river in eastern Hungary (15). Latest research into this event (Fig. 1) indicates its rapid accomplishment within one or two centuries just before and after 3000 BCE. Considering the vast geographical distances of 4500 km between the Tisza river and the Altai mountains, the absence of roads, and the small overall population sizes, it is difficult to envision how this expansion could have taken place without improved means of transport.



Fig. 1. Map of the Yamnaya and Afanasievo overall distribution.
Sites with individuals with skeletal markers for horsemanship are marked (black circles, Yamnaya; yellow circles, graves dated to other periods) (the background map is made with Natural Earth; free vector and raster map data at naturalearthdata.com; QGIS software). 1a, Strejnicu mound I grave 3 (I/3) grave in situ (photo credit: A. Frînculeasa, Prahova County Museum of History and Archaeology).