Son of Yamnaya.

In this 700+-comment thread, which seems to have become a dumping-ground for all DNA-related commentary, Dmitry Pruss said mildly but convincingly:

An ob gripe, I don’t think that it’s the best idea to discuss “everything DNA” in this, already oversize, thread…

So I’m hereby opening this as a continuation. If you have thoughts about genomic components and Denisovan signatures, this is the place for them!

Comments

  1. Trond Engen says

    I did recently link to a paper on Mongolia and the, eh, genetogenesis of the Xiongnu and the Mongolians in They Perished like Avars, where we have discussed much Post-Indo-European Steppe stuff. It didn’t attract any follow-up comments, so feel free to move it here.

  2. David Eddyshaw says

    Will we be seeing “Bride of Yamnaya” in due course?

  3. And possibly eventually Second Cousin Twice Removed of Yamnaya.

  4. Canonically, “Bride of Yamnaya” should have come first. Then “Son of Yamnaya”, then “Ghost of Yamnaya”, then “Yamnaya meets Dravidian”, then “House of Yamnaya”. The final(?) one should probably be a duo of comedians meet Yamnaya — I’d suggest “Nyland and Goropius”, but there is a surfeit of them to choose from.

    /Hammertime

  5. David Eddyshaw says

    Yamnaya in the KONGO. (Perhaps too controversial for these politically correct times …)

  6. Oh, the wind that blew through the whiskers on the flea in the hair on the tail of
    the dog of the daughter of the wife of the Dayak has just come to town….

  7. A new paper by Ioannidis et al., Native American gene flow into Polynesia predating Easter Island settlement is the most careful approach I have seen toward demonstrating early Polynesian-American contact using genetics. The paper finds an American genetic signature in Eastern Polynesian populations. What’s distinguishes this paper from earlier such studies is that it clearly separates the purported American signal from a European one; that it dates both plausibly; and that it clearly distinguishes different coastal American populations, and ties the source of the Polynesian signal specifically to a population in Colombia.

  8. Interesting!

  9. Trond Engen says

    Y: Ioannidis et al 2020

    We briefly discussed it here back in July. I still haven’t read the full text.

    Dmitry (in Mother of Yamnaya): (Huang et al 2020).

    I love it. This seems to take historical genetics to a whole new level, using the sheer power of numbers to shake out genetic commonalities that can be traced back to a common ancestor. The multi-ethno-linguistic matrixes are essentially the comparative method on genomes, but used to identify the oldest common elements rather than to reconstruct a complete ancestral genome.

  10. Trond Engen says

    A few seconds late to edit I meant to add a few random observations:

    They identify a “Northeast Asian Cluster”, which must be more or less identical with what Jeong et al dub ‘Ancient North Asians’ in the paper on the genetic history of Mongolia..

    They identify a gene flow from “European” into “Inland South Asian” (likely including the group speaking Proto-Sino-Tibetan) at ~5800 kA. I wonder where that came from.

    Note the predictive force. They posit a yet unsampled group in a specific location and with a specific genetic signature as the linguistic ancestors of Kra-Dai.

  11. Thanks, Trond. I somehow missed that discussion (and what followed it, which was very interesting, too.)

  12. Trond Engen says

    (This connects to several discussions. Most immediately me (July 29, 2020 at 7:25 am) in They perished like Avars:

    I got the Yu paper (thanks!) and just finishen reading it. Not much time to digest, but my takeout is that it’s a complementation to what we already knew about Eastern Siberia. On the ancient and basal level, it fills out the picture of the North Asian population that is ancestral to Non-Arctic Native Americans. Additionally it starts to untangle the movements and admixtures of the Late Neolithic and Early Bronze Age that eventually would lead to the formation of the ethnic and linguistic groups we know today. The plague is part of that. Intriguingly it’s found in two individuals without Steppe ancestry. They were from the same site, but one of them had migrated in his early childhood. The date and the strain of Yersinia pestis are practically identical to those of a Corded Ware individual from the Baltic. This fits well with the population crisis in Scandinavia before the arrival of the Bell Beakers.)

    A new Siberian archaeo-genetics paper from Dmitry on Facebook:

    Kılınç et al “Human population dynamics and Yersinia pestis in ancient northeast Asia” Sci. Adv. 2021; 7 : eabc4587.

    Their conclusions corroborate and expands on earlier studies:

    Conclusions
    Northeast Asia, particularly the Baikal adjacent area and the entire Russian Far East, presents a complex demographic picture with hitherto unknown genetic shifts since the post-LGM. The Trans-Baikal area displays few genetic turnovers with an extended period of genetic continuity over a period of c.6000 years. This unique demographical pattern throughout the Holocene stands in sharp contrast to the recurrent gene flow events of Cis-Baikal and Yakutia. We document that the human group that was represented by Khaiyrgas-1 must have dispersed to Yakutia after the LGM. This group was genetically distinct from the first inhabitants of the Siberia who settled the area before the LGM. The genetic legacy of this group is visible among human groups in the area ~6000 years later. Our data fit well with Belkachi groups as having key position in the ancestry of Paleo-Inuits who launched the second wave of gene flow into the Americas c.5000 years ago. We also document the presence of the most northeastern occurrence of ancient Y. pestis in the less populated Yakutia region and in the highly connected Cis-Baikal area. The bacterium may well have had consequences in shaping human population dynamics in both regions, visible in the reduction in the effective population size and the genetic diversity levels ~4400 years ago. Consistent with the finding of the same bacterium in the Lake Baikal region during the Bronze Age ([Yu et al 2020]), this finding suggests that a plague pandemic in this part of northeast Asia could be a hypothesis worth exploring with more data. Our results demonstrate a complex demography in northeast Asia from the Late Upper Paleolithic up until the Medieval era in which Siberian populations expanded interacting with each other and with populations from distant geographical areas.

    Apart from that, the paper is unusually hard to digest, but the supplementary text is more readable. I guess they had to edit it down to the available number of pages. Anyway…

    Expanding on Yu et al this study makes it very likely that there was a regional plague pandemic at around the year 2500 BCE. In my view the region could well turn out to be the entire continent, but there’s not enough data to tell yet. A few centuries later the bacterium is found at the Kolyma river in the farthest end of Yakutia. I’d think that to spread in a sparsely populated region like that, this early incarnation of the plague must have been both a slow killer and independent of rats.

    Something close to the source population of Paleo-Eskimos (and hence also of Na-Dene?) is found with the sampling of two 7th millennium BP individuals from the region of Yakutsk in Yakutia, associated with the Belkachi culture and its immediate predecessor, the Syalakh culture. This is in line with earlier hypotheses based on material culture. The two seem to be close to a mid-9th millennium BP individual from east of Lake Baikal, also in line with hypotheses from material culture. All three are said to show genetic affinity with modern Chukotko-Kamchatkans — as is Saqqaq.

    Two 5th millenium BP individuals from the Lena Basin and three 4th millenium BP individuals from the Kolyma River further northeast form a distinct group, apparently descended from Syalakh/Belkachi with additional admixture from southeast. An interesting outlier was left unmentioned in the main text but shown on the maps and diagrams, where it’s intriguingly grouped with the Yakutian individuals. This is a mid-5th millenium BP individual from south of Krasnoyarsk who seems to fit perfectly within the contemporary population in the Lena Basin. Is this the first Yeniseian? This individual also shows evidence of a recent genetic bottleneck, in line with the plague hypothesis.

    The Syalakh/Belkachi cultures are also thought to be ancestral to the Bronze Age Ymyyakhtakh culture that spread almost explosively along the Arctic coast in the late 2nd millennium BCE. The Kolyma individuals are late enough that they could be part of this movement, but I can’t find anything on their cultural affinity.

  13. Trond Engen says

    I’m on record suggesting a Dene-Yeniseian homeland (providing there is such a thing as Dene-Yeniseian) on the Arctic Coast. I’ll note that a mobile riverine culture on the Lena could easily spill over into the Yenisei Basin via the Angara or Tunguska rivers (or vice versa). It’s the distance from there to Alaska that disturbs me. The ancestors of the Paleo-Eskimos (and/or Na-Dene) would have migrated from the Lena Basin long before those of the Syalakh-Belkachi descendants found on the Kolyma River. For the Yeniseian branch to have been brought from the Lena to the Yenisei in the 5th millennium BP, we’d have to suppose that the stay-behind groups on the Lena were Pre-Proto-Yeniseian for a long time, even as new East Asian groups moved into the area and were integrated in its genetic profile. If so, also the movers north should be (Para-)Pre-Proto-Yeniseians. Maybe these coastal Leniseians were yukagrified from the west.

  14. It is a mainstream view in Russia that Yukaghir languages came into region with the Bronze Age Ymyyakhtakh culture in late 2nd millennium BC.

    From Baikal region, but their original homeland was further west, closer to Urals.

  15. Trond Engen says

    Since this is the Great Eurasian Plague thread, I’ll link to

    Julian Susat et al: A 5,000-year-old hunter-gatherer already plagued by Yersinia pestis Cell Reports, 2021

    Summary
    A 5,000-year-old Yersinia pestis genome (RV 2039) is reconstructed from a hunter-fisher-gatherer (5300–5050 cal BP) buried at Riņņukalns, Latvia. RV 2039 is the first in a series of ancient strains that evolved shortly after the split of Y. pestis from its antecessor Y. pseudotuberculosis ∼7,000 years ago. The genomic and phylogenetic characteristics of RV 2039 are consistent with the hypothesis that this very early Y. pestis form was most likely less transmissible and maybe even less virulent than later strains. Our data do not support the scenario of a prehistoric pneumonic plague pandemic, as suggested previously for the Neolithic decline. The geographical and temporal distribution of the few prehistoric Y. pestis cases reported so far is more in agreement with single zoonotic events.

    (Link from Dmitry, as usual)

    The oldest and most basal strain of Y, pestis yet has been discovered in a 5300-5050 cal. BP hunter-gatherer from northern Latvia. Needless to say, the last line of the summary is controversial. But since every instance of the plague is a zoonosis, the controverse is really about whether the plague is spreading as a pandemic among rodent parasites on human society. It’s when Y. pestis becomes pandemic (or endemic) among rodents, and the bacterium gains the ability to infect humans easily, that the zoonosis in humans becomes pandemic by extension.

    Here’s a thought-provoking paragraph from the discussion:

    Modern Y. pestis can be transmitted from animals (e.g., rodents) to humans (Demeure et al., 2019). It is possible that hunter-gatherers, who frequently killed rodents for food or personal decoration, contracted Y. pestis or its antecessor Y. pseudotuberculosis directly from animals. Interestingly, at the Riņņukalns site, beaver (Castor fiber) was the most frequently recorded species among the archaeozoological finds excavated by Sievers (Rütimeyer, 1877). Beavers are a common carrier of Y. pseudotuberculosis, which directly precedes our early Y. pestis strain (Gaydos et al., 2009). Despite this interesting observation, it remains unknown to what degree hunter-gatherers may have played a role in the zoonotic emergence, early evolution, or spread of Y. pestis.

    The question of how a rodent disease could trigger a human pandemic in a sparsely populated region of Eurasia is important, and I’m trying to get my head around it upthread. So maybe the authors are right and the first instances were isolated infections. Maybe, even, that the plague never was pandemic among hunter-gatherers. Still, I think hunter-gatherers with early Y. pestis are significant. As incrisingly deadly ad/or infectious strains of Yersinia spread among wild rodents, hunter-gatherers (beaver hunters?) could have adapted (by non-fatal exposure or genetic selection) before it infected the rats of the agriculturalists, and they would then be in a position to fill the void after the first plague.

  16. @Trond Engen: It seems to me that the terminology with early plague strains is bit tricky—being based, in part, on what appears to have been an erroneous assumption about how the modern plague strain developed (and thus where to place the dividing line between Yersinia pseudotuberculosis and Y. pestis). As I understand it, it is conventional to call all bacterial lineages with the pMT1 and pPCP1 plasmids Y. pestis. However, it is now known from very early genomes (and according to that Cell Reports paper, the Rinnukalns genetic data confirms this) that pMT1 was actually acquired without the gene for the key virulence factor ymt (Yersinia murine toxin). Only later was the gene for ymt, which makes it much easier for the bacteria to thrive inside the flea vectors, added to the plasmid—meaning that assimilation of the plasmid itself was not one of the primary enablers in the development pestis-level human infectivity. Nomenclature will presumably get even trickier if fossil genomes with only one of the pMT1 or pPCP1 plasmids are found (which has not, to my knowledge, been observed thus far).

  17. Trond Engen says

    @Brett: Thanks. I couldn’t have written that, but I agree.

  18. Dmitry Pruss on Facebook linked to these interesting papers:

    The origins and spread of domestic horses from the Western Eurasian steppes:

    Our results reject the commonly held association between horseback riding and the massive expansion of Yamnaya steppe pastoralists into Europe ~3,000 BCE driving the spread of Indo-European languages. This contrasts with the situation in Asia where Indo-Iranian languages, chariots and horses spread together, following the early second millennium BCE Sintashta culture.

    Dairying enabled Early Bronze Age Yamnaya steppe expansions:

    Our results point to a potential epicentre for horse domestication in the Pontic–Caspian steppe by the third millennium bc, and offer strong support for the notion that the novel exploitation of secondary animal products was a key driver of the expansions of Eurasian steppe pastoralists by the Early Bronze Age.

  19. horse domestication … the novel exploitation of secondary animal products

    Is transport an “animal product” ? Or is primarily horse dung meant ?

  20. Aren’t dairy products the reference there — meat being the only use considered primary?

  21. Yes, if one bothers to click through, one finds (bolding added):

    Here we draw on proteomic analysis of dental calculus from individuals from the western Eurasian steppe to demonstrate a major transition in dairying at the start of the Bronze Age. The rapid onset of ubiquitous dairying at a point in time when steppe populations are known to have begun dispersing offers critical insight into a key catalyst of steppe mobility. The identification of horse milk proteins also indicates horse domestication by the Early Bronze Age, which provides support for its role in steppe dispersals.

    Of course, the reference to “dairying” in the title might have been a clue.

  22. Adding a reference to “Horsing around” in the title would have been yet another welcome clue.

  23. Perhaps “dairying” was misread as “draying”, a nonce synonym for “drayage” . . .

  24. It”s the same paper jack morava linked to in another thread recently. I haven’t had time to read it, but I immediately like it. And I don’t know if it rejects the horse hypothesis as much as nuances and complements it.

  25. @Trond Engen,

    I started trying to take this seriously when I saw

    https://en.wikipedia.org/wiki/Trundholm_sun_chariot

  26. David Marjanović says

    Open-access paper on how Japan was settled in three stages.

  27. David Marjanović says

    Five open-access papers and their abstracts:

    Ancient Mitochondrial Genomes Reveal Extensive Genetic Influence of the Steppe Pastoralists in Western Xinjiang

    The population prehistory of Xinjiang has been a hot topic among geneticists, linguists, and archaeologists. Current ancient DNA studies in Xinjiang exclusively suggest an admixture model for the populations in Xinjiang since the early Bronze Age. However, almost all of these studies focused on the northern and eastern parts of Xinjiang; the prehistoric demographic processes that occurred in western Xinjiang have been seldomly reported. By analyzing complete mitochondrial sequences from the Xiabandi (XBD) cemetery (3,500–3,300 BP), the up-to-date earliest cemetery excavated in western Xinjiang, we show that all the XBD mitochondrial sequences fall within two different West Eurasian mitochondrial DNA (mtDNA) pools, indicating that the migrants into western Xinjiang from west Eurasians were a consequence of the early expansion of the middle and late Bronze Age steppe pastoralists (Steppe_MLBA), admixed with the indigenous populations from Central Asia. Our study provides genetic links for an early existence of the Indo-Iranian language in southwestern Xinjiang and suggests that the existence of Andronovo culture in western Xinjiang involved not only the dispersal of ideas but also population movement.

    Genomic Insight Into the Population Admixture History of Tungusic-Speaking Manchu People in Northeast China

    Manchu is the third-largest ethnic minority in China and has the largest population size among the Tungusic-speaking groups. However, the genetic origin and admixture history of the Manchu people are far from clear due to the sparse sampling and a limited number of markers genotyped. Here, we provided the first batch of genome-wide data of genotyping approximate 700,000 single-nucleotide polymorphisms (SNPs) in 93 Manchu individuals collected from northeast China. We merged the newly generated data with data of publicly available modern and ancient East Asians to comprehensively characterize the genetic diversity and fine-scale population structure, as well as explore the genetic origin and admixture history of northern Chinese Manchus. We applied both descriptive methods of ADMIXTURE, fineSTRUCTURE, FST, TreeMix, identity by decedent (IBD), principal component analysis (PCA), and qualitative f-statistics (f3, f4, qpAdm, and qpWave). We found that Liaoning Manchus have a close genetic relationship and significant admixture signal with northern Han Chinese, which is in line with the cluster patterns in the haplotype-based results. Additionally, the qpAdm-based admixture models showed that modern Manchu people were formed as major ancestry related to Yellow River farmers and minor ancestry linked to ancient populations from Amur River Bain, or others. In summary, the northeastern Chinese Manchu people in Liaoning were an exception to the coherent genetic structure of Tungusic-speaking populations, probably due to the large-scale population migrations and genetic admixtures in the past few hundred years.

    Genomic Insight Into the Population Structure and Admixture History of Tai-Kadai-Speaking Sui People in Southwest China

    Sui people, which belong to the Tai-Kadai-speaking family, remain poorly characterized due to a lack of genome-wide data. To infer the fine-scale population genetic structure and putative genetic sources of the Sui people, we genotyped 498,655 genome-wide single-nucleotide polymorphisms (SNPs) using SNP arrays in 68 Sui individuals from seven indigenous populations in Guizhou province and Guangxi Zhuang Autonomous Region in Southwest China and co-analyzed with available East Asians via a series of population genetic methods including principal component analysis (PCA), ADMIXTURE, pairwise Fst genetic distance, f-statistics, qpWave, and qpAdm. Our results revealed that Guangxi and Guizhou Sui people showed a strong genetic affinity with populations from southern China and Southeast Asia, especially Tai-Kadai- and Hmong-Mien-speaking populations as well as ancient Iron Age Taiwan Hanben, Gongguan individuals supporting the hypothesis that Sui people came from southern China originally. The indigenous Tai-Kadai-related ancestry (represented by Li), Northern East Asian-related ancestry, and Hmong-Mien-related lineage contributed to the formation processes of the Sui people. We identified the genetic substructure within Sui groups: Guizhou Sui people were relatively homogeneous and possessed similar genetic profiles with neighboring Tai-Kadai-related populations, such as Maonan. While Sui people in Yizhou and Huanjiang of Guangxi might receive unique, additional gene flow from Hmong-Mien-speaking populations and Northern East Asians, respectively, after the divergence within other Sui populations. Sui people could be modeled as the admixture of ancient Yellow River Basin farmer-related ancestry (36.2–54.7%) and ancient coastal Southeast Asian-related ancestry (45.3–63.8%). We also identified the potential positive selection signals related to the disease susceptibility in Sui people via integrated haplotype score (iHS) and number of segregating sites by length (nSL) scores. These genomic findings provided new insights into the demographic history of Tai-Kadai-speaking Sui people and their interaction with neighboring populations in Southern China.

    Peopling History of the Tibetan Plateau and Multiple Waves of Admixture of Tibetans Inferred From Both Ancient and Modern Genome-Wide Data

    Archeologically attested human occupation on the Tibetan Plateau (TP) can be traced back to 160 thousand years ago (kya) via the archaic Xiahe people and 30∼40 kya via the Nwya Devu anatomically modern human. However, the history of the Tibetan populations and their migration inferred from the ancient and modern DNA remains unclear. Here, we performed the first ancient and modern genomic meta-analysis among 3,017 Paleolithic to present-day Eastern Eurasian genomes (2,444 modern individuals from 183 populations and 573 ancient individuals). We identified a close genetic connection between the ancient-modern highland Tibetans and lowland island/coastal Neolithic Northern East Asians (NEA). This observed genetic affinity reflected the primary ancestry of high-altitude Tibeto-Burman speakers originated from the Neolithic farming populations in the Yellow River Basin. The identified pattern was consistent with the proposed common north-China origin hypothesis of the Sino-Tibetan languages and dispersal patterns of the northern millet farmers. We also observed the genetic differentiation between the highlanders and lowland NEAs. The former harbored more deeply diverged Hoabinhian/Onge-related ancestry and the latter possessed more Neolithic southern East Asian (SEA) or Siberian-related ancestry. Our reconstructed qpAdm and qpGraph models suggested the co-existence of Paleolithic and Neolithic ancestries in the Neolithic to modern East Asian highlanders. Additionally, we found that Tibetans from Ü-Tsang/Ando/Kham regions showed a strong population stratification consistent with their cultural background and geographic terrain. Ü-Tsang Tibetans possessed a stronger Chokhopani-affinity, Ando Tibetans had more Western Eurasian related ancestry and Kham Tibetans harbored greater Neolithic southern EA ancestry. Generally, ancient and modern genomes documented multiple waves of human migrations in the TP’s past. The first layer of local hunter-gatherers mixed with incoming millet farmers and arose the Chokhopani-associated Proto-Tibetan-Burman highlanders, which further respectively mixed with additional genetic contributors from the western Eurasian Steppe, Yellow River and Yangtze River and finally gave rise to the modern Ando, Ü-Tsang and Kham Tibetans.

    The Opportunities and Challenges of Integrating Population Histories Into Genetic Studies for Diverse Populations: A Motivating Example From Native Hawaiians

    There is a well-recognized need to include diverse populations in genetic studies, but several obstacles continue to be prohibitive, including (but are not limited to) the difficulty of recruiting individuals from diverse populations in large numbers and the lack of representation in available genomic references. These obstacles notwithstanding, studying multiple diverse populations would provide informative, population-specific insights. Using Native Hawaiians as an example of an understudied population with a unique evolutionary history, I will argue that by developing key genomic resources and integrating evolutionary thinking into genetic epidemiology, we will have the opportunity to efficiently advance our knowledge of the genetic risk factors, ameliorate health disparity, and improve healthcare in this underserved population.

  28. Thanks for those!

  29. David Marjanović says

    I haven’t had time to read them myself yet.

  30. Trond Engen says

    Thanks! Will read.

  31. Trond Engen says

    I’m frantically trying to get up to date with all these papers.

    The origins and spread of domestic horses from the Western Eurasian steppes has showed up as open access in Nature.

    (Quoting a bit more)

    Abstract
    Domestication of horses fundamentally transformed long-range mobility and warfare. However, modern domesticated breeds do not descend from the earliest domestic horse lineage associated with archaeological evidence of bridling, milking and corralling at Botai, Central Asia around 3500 BC. Other longstanding candidate regions for horse domestication, such as Iberia and Anatolia, have also recently been challenged. Thus, the genetic, geographic and temporal origins of modern domestic horses have remained unknown. Here we pinpoint the Western Eurasian steppes, especially the lower Volga-Don region, as the homeland of modern domestic horses. Furthermore, we map the population changes accompanying domestication from 273 ancient horse genomes. This reveals that modern domestic horses ultimately replaced almost all other local populations as they expanded rapidly across Eurasia from about 2000 BC, synchronously with equestrian material culture, including Sintashta spoke-wheeled chariots. We find that equestrianism involved strong selection for critical locomotor and behavioural adaptations at the GSDMC and ZFPM1 genes. Our results reject the commonly held association between horseback riding and the massive expansion of Yamnaya steppe pastoralists into Europe around 3000 BC driving the spread of Indo-European languages. This contrasts with the scenario in Asia where Indo-Iranian languages, chariots and horses spread together, following the early second millennium BC Sintashta culture.

    […]

    Discussion
    This work resolves longstanding debates about the origins and spread of domestic horses. Whereas horses living in the Western Eurasia steppes in the late fourth and early third millennia BC were the ancestors of DOM2 horses, there is no evidence that they facilitated the expansion of the human genetic steppe ancestry into Europe as previously hypothesized. Instead of horse-mounted warfare, declining populations during the European late Neolithic may thus have opened up an opportunity for a westward expansion of steppe pastoralists. Yamnaya horses at Repin and Turganik carried more DOM2 genetic affinity than presumably wild horses from hunter-gatherer sites of the sixth millennium BC (NEO-NCAS, from approximately 5500–5200 BC), which may suggest early horse management and herding practices. Regardless, Yamnaya pastoralism did not spread horses far outside their native range, similar to the Botai horse domestication, which remained a localized practice within a sedentary settlement system. The globalization stage started later, when DOM2 horses dispersed outside their core region, first reaching Anatolia, the lower Danube, Bohemia and Central Asia by approximately 2200 to 2000 BC, then Western Europe and Mongolia soon afterwards, ultimately replacing all local populations by around 1500 to 1000 BC. This process first involved horseback riding, as spoke-wheeled chariots represent later technological innovations, emerging around 2000 to 1800 BC in the Trans-Ural Sintashta culture. The weaponry, warriors and fortified settlements associated with this culture may have arisen in response to increased aridity and competition for critical grazing lands, intensifying territoriality and hierarchy. This may have provided the basis for the conquests over the subsequent centuries that resulted in an almost complete human and horse genetic turnover in Central Asian steppes. The expansion to the Carpathian basin, and possibly Anatolia and the Levant, involved a different scenario in which specialized horse trainers and chariot builders spread with the horse trade and riding. In both cases, horses with reduced back pathologies and enhanced docility would have facilitated Bronze Age elite long-distance trade demands and become a highly valued commodity and status symbol, resulting in rapid diaspora. We, however, acknowledge substantial spatiotemporal variability and evidential bias towards elite activities, so we do not discount additional, harder to evidence, factors in equine dispersal.

    Our results also have important implications for mechanisms underpinning two major language dispersals. The expansion of the Indo-European language family from the Western Eurasia steppes has traditionally been associated with mounted pastoralism, with the CWC serving as a major stepping stone in Europe. However, while there is overwhelming lexical evidence for horse domestication, horse-drawn chariots and derived mythologies in the Indo-Iranian branch of the Indo-European family, the linguistic indications of horse-keeping practices at the deeper Proto-Indo-European level are in fact ambiguous (Supplementary Discussion) . The limited presence of horses in CWC assemblages and the local genetic makeup of CWC specimens reject scenarios in which horses were the primary driving force behind the initial spread of Indo-European languages in Europe. By contrast, DOM2 dispersal in Asia during the early-to-mid second millennium BC was concurrent with the spread of chariotry and Indo-Iranian languages, whose earliest speakers are linked to populations that directly preceded the Sintashta culture. We thus conclude that the new package of chariotry and improved breed of horses, including chestnut coat colouration documented both linguistically (Supplementary Discussion) and genetically (Extended Data Fig. 8), transformed Eurasian Bronze Age societies globally within a few centuries after about 2000 BC. The adoption of this new institution, whether for warfare, prestige or both, probably varied between decentralized chiefdoms in Europe and urbanized states in Western Asia. The results thus open up new research avenues into the historical developments of these different societal trajectories.

    That is, the rapid spread of Steppe ancestry in Europe wasn’t carried on horseback. It wasn’t even bringing horses along. Horses bred for riding and chariotry came a millennium later, and we may ask what upheavals that caused.

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