Yamnaya ancestry: mapping the Proto-Indo-European expansions

steppe-ancestry-expansion-europe

The latest papers from Ning et al. Cell (2019) and Anthony JIES (2019) have offered some interesting new data, supporting once more what could be inferred since 2015, and what was evident in population genomics since 2017: that Proto-Indo-Europeans expanded under R1b bottlenecks, and that the so-called “Steppe ancestry” referred to two different components, one – Yamnaya or Steppe_EMBA ancestry – expanding with Pro-Indo-Europeans, and the other one – Corded Ware or Steppe_MLBA ancestry – expanding with Uralic speakers.

The following maps are based on formal stats published in the papers and supplementary materials from 2015 until today, mainly on Wang et al. (2018 & 2019), Mathieson et al. (2018) and Olalde et al. (2018), and others like Lazaridis et al. (2016), Lazaridis et al. (2017), Mittnik et al. (2018), Lamnidis et al. (2018), Fernandes et al. (2018), Jeong et al. (2019), Olalde et al. (2019), etc.

NOTE. As in the Corded Ware ancestry maps, the selected reports in this case are centered on the prototypical Yamnaya ancestry vs. other simplified components, so everything else refers to simplistic ancestral components widespread across populations that do not necessarily share any recent connection, much less a language. In fact, most of the time they clearly didn’t. They can be interpreted as “EHG that is not part of the Yamnaya component”, or “CHG that is not part of the Yamnaya component”. They can’t be read as “expanding EHG people/language” or “expanding CHG people/language”, at least no more than maps of “Steppe ancestry” can be read as “expanding Steppe people/language”. Also, remember that I have left the default behaviour for color classification, so that the highest value (i.e. 1, or white colour) could mean anything from 10% to 100% depending on the specific ancestry and period; that’s what the legend is for… But, fere libenter homines id quod volunt credunt.

Sections:

  1. Neolithic or the formation of Early Indo-European
  2. Eneolithic or the expansion of Middle Proto-Indo-European
  3. Chalcolithic / Early Bronze Age or the expansion of Late Proto-Indo-European
  4. European Early Bronze Age and MLBA or the expansion of Late PIE dialects

1. Neolithic

Anthony (2019) agrees with the most likely explanation of the CHG component found in Yamnaya, as derived from steppe hunter-fishers close to the lower Volga basin. The ultimate origin of this specific CHG-like component that eventually formed part of the Pre-Yamnaya ancestry is not clear, though:

The hunter-fisher camps that first appeared on the lower Volga around 6200 BC could represent the migration northward of un-admixed CHG hunter-fishers from the steppe parts of the southeastern Caucasus, a speculation that awaits confirmation from aDNA.

neolithic-chg-ancestry
Natural neighbor interpolation of CHG ancestry among Neolithic populations. See full map.

The typical EHG component that formed part eventually of Pre-Yamnaya ancestry came from the Middle Volga Basin, most likely close to the Samara region, as shown by the sampled Samara hunter-gatherer (ca. 5600-5500 BC):

After 5000 BC domesticated animals appeared in these same sites in the lower Volga, and in new ones, and in grave sacrifices at Khvalynsk and Ekaterinovka. CHG genes and domesticated animals flowed north up the Volga, and EHG genes flowed south into the North Caucasus steppes, and the two components became admixed.

neolithic-ehg-ancestry
Natural neighbor interpolation of EHG ancestry among Neolithic populations. See full map.

To the west, in the Dnieper-Dniester area, WHG became the dominant ancestry after the Mesolithic, at the expense of EHG, revealing a likely mating network reaching to the north into the Baltic:

Like the Mesolithic and Neolithic populations here, the Eneolithic populations of Dnieper-Donets II type seem to have limited their mating network to the rich, strategic region they occupied, centered on the Rapids. The absence of CHG shows that they did not mate frequently if at all with the people of the Volga steppes (…)

neolithic-whg-ancestry
Natural neighbor interpolation of WHG ancestry among Neolithic populations. See full map.

North-West Anatolia Neolithic ancestry, proper of expanding Early European farmers, is found up to border of the Dniester, as Anthony (2007) had predicted.

neolithic-anatolia-farmer-ancestry
Natural neighbor interpolation of Anatolia Neolithic ancestry among Neolithic populations. See full map.

2. Eneolithic

From Anthony (2019):

After approximately 4500 BC the Khvalynsk archaeological culture united the lower and middle Volga archaeological sites into one variable archaeological culture that kept domesticated sheep, goats, and cattle (and possibly horses). In my estimation, Khvalynsk might represent the oldest phase of PIE.

(…) this middle Volga mating network extended down to the North Caucasian steppes, where at cemeteries such as Progress-2 and Vonyuchka, dated 4300 BC, the same Khvalynsk-type ancestry appeared, an admixture of CHG and EHG with no Anatolian Farmer ancestry, with steppe-derived Y-chromosome haplogroup R1b. These three individuals in the North Caucasus steppes had higher proportions of CHG, overlapping Yamnaya. Without any doubt, a CHG population that was not admixed with Anatolian Farmers mated with EHG populations in the Volga steppes and in the North Caucasus steppes before 4500 BC. We can refer to this admixture as pre-Yamnaya, because it makes the best currently known genetic ancestor for EHG/CHG R1b Yamnaya genomes.

From Wang et al (2019):

Three individuals from the sites of Progress 2 and Vonyuchka 1 in the North Caucasus piedmont steppe (‘Eneolithic steppe’), which harbour EHG and CHG related ancestry, are genetically very similar to Eneolithic individuals from Khvalynsk II and the Samara region. This extends the cline of dilution of EHG ancestry via CHG-related ancestry to sites immediately north of the Caucasus foothills

eneolithic-pre-yamnaya-ancestry
Natural neighbor interpolation of Pre-Yamnaya ancestry among Neolithic populations. See full map. This map corresponds roughly to the map of Khvalynsk-Novodanilovka expansion, and in particular to the expansion of horse-head pommel-scepters (read more about Khvalynsk, and specifically about horse symbolism)

NOTE. Unpublished samples from Ekaterinovka have been previously reported as within the R1b-L23 tree. Interestingly, although the Varna outlier is a female, the Balkan outlier from Smyadovo shows two positive SNP calls for hg. R1b-M269. However, its poor coverage makes its most conservative haplogroup prediction R-M343.

The formation of this Pre-Yamnaya ancestry sets this Volga-Caucasus Khvalynsk community apart from the rest of the EHG-like population of eastern Europe.

eneolithic-ehg-ancestry
Natural neighbor interpolation of non-Pre-Yamnaya EHG ancestry among Eneolithic populations. See full map.

Anthony (2019) seems to rely on ADMIXTURE graphics when he writes that the late Sredni Stog sample from Alexandria shows “80% Khvalynsk-type steppe ancestry (CHG&EHG)”. While this seems the most logical conclusion of what might have happened after the Suvorovo-Novodanilovka expansion through the North Pontic steppes (see my post on “Steppe ancestry” step by step), formal stats have not confirmed that.

In fact, analyses published in Wang et al. (2019) rejected that Corded Ware groups are derived from this Pre-Yamnaya ancestry, a reality that had been already hinted in Narasimhan et al. (2018), when Steppe_EMBA showed a poor fit for expanding Srubna-Andronovo populations. Hence the need to consider the whole CHG component of the North Pontic area separately:

eneolithic-chg-ancestry
Natural neighbor interpolation of non-Pre-Yamnaya CHG ancestry among Eneolithic populations. See full map. You can read more about population movements in the late Sredni Stog and closer to the Proto-Corded Ware period.

NOTE. Fits for WHG + CHG + EHG in Neolithic and Eneolithic populations are taken in part from Mathieson et al. (2019) supplementary materials (download Excel here). Unfortunately, while data on the Ukraine_Eneolithic outlier from Alexandria abounds, I don’t have specific data on the so-called ‘outlier’ from Dereivka compared to the other two analyzed together, so these maps of CHG and EHG expansion are possibly showing a lesser distribution to the west than the real one ca. 4000-3500 BC.

eneolithic-whg-ancestry
Natural neighbor interpolation of WHG ancestry among Eneolithic populations. See full map.

Anatolia Neolithic ancestry clearly spread to the east into the north Pontic area through a Middle Eneolithic mating network, most likely opened after the Khvalynsk expansion:

eneolithic-anatolia-farmer-ancestry
Natural neighbor interpolation of Anatolia Neolithic ancestry among Eneolithic populations. See full map.
eneolithic-iran-chl-ancestry
Natural neighbor interpolation of Iran Chl. ancestry among Eneolithic populations. See full map.

Regarding Y-chromosome haplogroups, Anthony (2019) insists on the evident association of Khvalynsk, Yamnaya, and the spread of Pre-Yamnaya and Yamnaya ancestry with the expansion of elite R1b-L754 (and some I2a2) individuals:

eneolithic-early-y-dna
Y-DNA haplogroups in West Eurasia during the Early Eneolithic in the Pontic-Caspian steppes. See full map, and see culture, ADMIXTURE, Y-DNA, and mtDNA maps of the Early Eneolithic and Late Eneolithic.

3. Early Bronze Age

Data from Wang et al. (2019) show that Corded Ware-derived populations do not have good fits for Eneolithic_Steppe-like ancestry, no matter the model. In other words: Corded Ware populations show not only a higher contribution of Anatolia Neolithic ancestry (ca. 20-30% compared to the ca. 2-10% of Yamnaya); they show a different EHG + CHG combination compared to the Pre-Yamnaya one.

eneolithic-steppe-best-fits
Supplementary Table 13. P values of rank=2 and admixture proportions in modelling Steppe ancestry populations as a three-way admixture of Eneolithic steppe Anatolian_Neolithic and WHG using 14 outgroups.
Left populations: Test, Eneolithic_steppe, Anatolian_Neolithic, WHG.
Right populations: Mbuti.DG, Ust_Ishim.DG, Kostenki14, MA1, Han.DG, Papuan.DG, Onge.DG, Villabruna, Vestonice16, ElMiron, Ethiopia_4500BP.SG, Karitiana.DG, Natufian, Iran_Ganj_Dareh_Neolithic.

Yamnaya Kalmykia and Afanasievo show the closest fits to the Eneolithic population of the North Caucasian steppes, rejecting thus sizeable contributions from Anatolia Neolithic and/or WHG, as shown by the SD values. Both probably show then a Pre-Yamnaya ancestry closest to the late Repin population.

wang-eneolithic-steppe-caucasus-yamnaya
Modelling results for the Steppe and Caucasus cluster. Admixture proportions based on (temporally and geographically) distal and proximal models, showing additional AF ancestry in Steppe groups and additional gene flow from the south in some of the Steppe groups as well as the Caucasus groups. See tables above. Modified from Wang et al. (2019). Within a blue square, Yamnaya-related groups; within a cyan square, Corded Ware-related groups. Green background behind best p-values. In red circle, SD of AF/WHG ancestry contribution in Afanasevo and Yamnaya Kalmykia, with ranges that almost include 0%.

EBA maps include data from Wang et al. (2018) supplementary materials, specifically unpublished Yamnaya samples from Hungary that appeared in analysis of the preprint, but which were taken out of the definitive paper. Their location among Yamnaya settlers from Hungary is speculative, although most uncovered kurgans in Hungary are concentrated in the Tisza-Danube interfluve.

eba-yamnaya-ancestry
Natural neighbor interpolation of Pre-Yamnaya ancestry among Early Bronze Age populations. See full map. This map corresponds roughly with the known expansion of late Repin/Yamnaya settlers.

The Y-chromosome bottleneck of elite males from Proto-Indo-European clans under R1b-L754 and some I2a2 subclades, already visible in the Khvalynsk sampling, became even more noticeable in the subsequent expansion of late Repin/early Yamnaya elites under R1b-L23 and I2a-L699:

chalcolithic-early-y-dna
Y-DNA haplogroups in West Eurasia during the Yamnaya expansion. See full map and maps of cultures, ADMIXTURE, Y-DNA, and mtDNA of the Early Chalcolithic and Yamnaya Hungary.

Maps of CHG, EHG, Anatolia Neolithic, and probably WHG show the expansion of these components among Corded Ware-related groups in North Eurasia, apart from other cultures close to the Caucasus:

NOTE. For maps with actual formal stats of Corded Ware ancestry from the Early Bronze Age to the modern times, you can read the post Corded Ware ancestry in North Eurasia and the Uralic expansion.

eba-chg-ancestry
Natural neighbor interpolation of non-Pre-Yamnaya CHG ancestry among Early Bronze Age populations. See full map.
eba-ehg-ancestry
Natural neighbor interpolation of non-Pre-Yamnaya EHG ancestry among Early Bronze Age populations. See full map.
eba-whg-ancestry
Natural neighbor interpolation of WHG ancestry among Early Bronze Age populations. See full map.
eba-anatolia-farmer-ancestry
Natural neighbor interpolation of Anatolia Neolithic ancestry among Early Bronze Age populations. See full map.
eba-iran-chl-ancestry
Natural neighbor interpolation of Iran Chl. ancestry among Early Bronze Age populations. See full map.

4. Middle to Late Bronze Age

The following maps show the most likely distribution of Yamnaya ancestry during the Bell Beaker-, Balkan-, and Sintashta-Potapovka-related expansions.

4.1. Bell Beakers

The amount of Yamnaya ancestry is probably overestimated among populations where Bell Beakers replaced Corded Ware. A map of Yamnaya ancestry among Bell Beakers gets trickier for the following reasons:

  • Expanding Repin peoples of Pre-Yamnaya ancestry must have had admixture through exogamy with late Sredni Stog/Proto-Corded Ware peoples during their expansion into the North Pontic area, and Sredni Stog in turn had probably some Pre-Yamnaya admixture, too (although they don’t appear in the simplistic formal stats above). This is supported by the increase of Anatolia farmer ancestry in more western Yamna samples.
  • Later, Yamnaya admixed through exogamy with Corded Ware-like populations in Central Europe during their expansion. Even samples from the Middle to Upper Danube and around the Lower Rhine will probably show increasing contributions of Steppe_MLBA, at the same time as they show an increasing proportion of EEF-related ancestry.
  • To complicate things further, the late Corded Ware Espersted family (from ca. 2500 BC or later) shows, in turn, what seems like a recent admixture with Yamnaya vanguard groups, with the sample of highest Yamnaya ancestry being the paternal uncle of other individuals (all of hg. R1a-M417), suggesting that there might have been many similar Central European mating networks from the mid-3rd millennium BC on, of (mainly) Yamnaya-like R1b elites displaying a small proportion of CW-like ancestry admixing through exogamy with Corded Ware-like peoples who already had some Yamnaya ancestry.
mlba-yamnaya-ancestry
Natural neighbor interpolation of Yamnaya ancestry among Middle to Late Bronze Age populations (Esperstedt CWC site close to BK_DE, label is hidden by BK_DE_SAN). See full map. You can see how this map correlated with the map of Late Copper Age migrations and Yamanaya into Bell Beaker expansion.

NOTE. Terms like “exogamy”, “male-driven migration”, and “sex bias”, are not only based on the Y-chromosome bottlenecks visible in the different cultural expansions since the Palaeolithic. Despite the scarce sampling available in 2017 for analysis of “Steppe ancestry”-related populations, it appeared to show already a male sex bias in Goldberg et al. (2017), and it has been confirmed for Neolithic and Copper Age population movements in Mathieson et al. (2018) – see Supplementary Table 5. The analysis of male-biased expansion of “Steppe ancestry” in CWC Esperstedt and Bell Beaker Germany is, for the reasons stated above, not very useful to distinguish their mutual influence, though.

Based on data from Olalde et al. (2019), Bell Beakers from Germany are the closest sampled ones to expanding East Bell Beakers, and those close to the Rhine – i.e. French, Dutch, and British Beakers in particular – show a clear excess “Steppe ancestry” due to their exogamy with local Corded Ware groups:

Only one 2-way model fits the ancestry in Iberia_CA_Stp with P-value>0.05: Germany_Beaker + Iberia_CA. Finding a Bell Beaker-related group as a plausible source for the introduction of steppe ancestry into Iberia is consistent with the fact that some of the individuals in the Iberia_CA_Stp group were excavated in Bell Beaker associated contexts. Models with Iberia_CA and other Bell Beaker groups such as France_Beaker (P-value=7.31E-06), Netherlands_Beaker (P-value=1.03E-03) and England_Beaker (P-value=4.86E-02) failed, probably because they have slightly higher proportions of steppe ancestry than the true source population.

olalde-iberia-chalcolithic

The exogamy with Corded Ware-like groups in the Lower Rhine Basin seems at this point undeniable, as is the origin of Bell Beakers around the Middle-Upper Danube Basin from Yamnaya Hungary.

To avoid this excess “Steppe ancestry” showing up in the maps, since Bell Beakers from Germany pack the most Yamnaya ancestry among East Bell Beakers outside Hungary (ca. 51.1% “Steppe ancestry”), I equated this maximum with BK_Scotland_Ach (which shows ca. 61.1% “Steppe ancestry”, highest among western Beakers), and applied a simple rule of three for “Steppe ancestry” in Dutch and British Beakers.

NOTE. Formal stats for “Steppe ancestry” in Bell Beaker groups are available in Olalde et al. (2018) supplementary materials (PDF). I didn’t apply this adjustment to Bk_FR groups because of the R1b Bell Beaker sample from the Champagne/Alsace region reported by Samantha Brunel that will pack more Yamnaya ancestry than any other sampled Beaker to date, hence probably driving the Yamnaya ancestry up in French samples.

The most likely outcome in the following years, when Yamnaya and Corded Ware ancestry are investigated separately, is that Yamnaya ancestry will be much lower the farther away from the Middle and Lower Danube region, similar to the case in Iberia, so the map above probably overestimates this component in most Beakers to the north of the Danube. Even the late Hungarian Beaker samples, who pack the highest Yamnaya ancestry (up to 75%) among Beakers, represent likely a back-migration of Moravian Beakers, and will probably show a contribution of Corded Ware ancestry due to the exogamy with local Moravian groups.

Despite this decreasing admixture as Bell Beakers spread westward, the explosive expansion of Yamnaya R1b male lineages (in words of David Reich) and the radical replacement of local ones – whether derived from Corded Ware or Neolithic groups – shows the true extent of the North-West Indo-European expansion in Europe:

chalcolithic-late-y-dna
Y-DNA haplogroups in West Eurasia during the Bell Beaker expansion. See full map and see maps of cultures, ADMIXTURE, Y-DNA, and mtDNA of the Late Copper Age and of the Yamnaya-Bell Beaker transition.

4.2. Palaeo-Balkan

There is scarce data on Palaeo-Balkan movements yet, although it is known that:

  1. Yamnaya ancestry appears among Mycenaeans, with the Yamnaya Bulgaria sample being its best current ancestral fit;
  2. the emergence of steppe ancestry and R1b-M269 in the eastern Mediterranean was associated with Ancient Greeks;
  3. Thracians, Albanians, and Armenians also show R1b-M269 subclades and “Steppe ancestry”.

4.3. Sintashta-Potapovka-Filatovka

Interestingly, Potapovka is the only Corded Ware derived culture that shows good fits for Yamnaya ancestry, despite having replaced Poltavka in the region under the same Corded Ware-like (Abashevo) influence as Sintashta.

This proves that there was a period of admixture in the Pre-Proto-Indo-Iranian community between CWC-like Abashevo and Yamnaya-like Catacomb-Poltavka herders in the Sintashta-Potapovka-Filatovka community, probably more easily detectable in this group because of the specific temporal and geographic sampling available.

srubnaya-yamnaya-ehg-chg-ancestry
Supplementary Table 14. P values of rank=3 and admixture proportions in modelling Steppe ancestry populations as a four-way admixture of distal sources EHG, CHG, Anatolian_Neolithic and WHG using 14 outgroups.
Left populations: Steppe cluster, EHG, CHG, WHG, Anatolian_Neolithic
Right populations: Mbuti.DG, Ust_Ishim.DG, Kostenki14, MA1, Han.DG, Papuan.DG, Onge.DG, Villabruna, Vestonice16, ElMiron, Ethiopia_4500BP.SG, Karitiana.DG, Natufian, Iran_Ganj_Dareh_Neolithic.

Srubnaya ancestry shows a best fit with non-Pre-Yamnaya ancestry, i.e. with different CHG + EHG components – possibly because the more western Potapovka (ancestral to Proto-Srubnaya Pokrovka) also showed good fits for it. Srubnaya shows poor fits for Pre-Yamnaya ancestry probably because Corded Ware-like (Abashevo) genetic influence increased during its formation.

On the other hand, more eastern Corded Ware-derived groups like Sintashta and its more direct offshoot Andronovo show poor fits with this model, too, but their fits are still better than those including Pre-Yamnaya ancestry.

mlba-ehg-ancestry
Natural neighbor interpolation of non-Pre-Yamnaya EHG ancestry among Middle to Late Bronze Age populations. See full map.
mlba-chg-ancestry
Natural neighbor interpolation of non-Pre-Yamnaya CHG ancestry among Middle to Late Bronze Age populations. See full map.
mlba-anatolia-farmer-ancestry
Natural neighbor interpolation of Anatolia Neolithic ancestry among Middle to Late Bronze Age populations. See full map.
mlba-iran-chl-ancestry
Natural neighbor interpolation of Iran Chl. ancestry among Middle to Late Bronze Age populations. See full map.

NOTE For maps with actual formal stats of Corded Ware ancestry from the Early Bronze Age to the modern times, you should read the post Corded Ware ancestry in North Eurasia and the Uralic expansion instead.

The bottleneck of Proto-Indo-Iranians under R1a-Z93 was not yet complete by the time when the Sintashta-Potapovka-Filatovka community expanded with the Srubna-Andronovo horizon:

early-bronze-age-y-dna
Y-DNA haplogroups in West Eurasia during the European Early Bronze Age. See full map and see maps of cultures, ADMIXTURE, Y-DNA, and mtDNA of the Early Bronze Age.

4.4. Afanasevo

At the end of the Afanasevo culture, at least three samples show hg. Q1a2-M25 (ca. 2900-2500 BC), which seemed to point to a resurgence of local lineages, despite continuity of the prototypical Pre-Yamnaya ancestry. On the other hand, Anthony (2019) makes this cryptic statement:

Yamnaya men were almost exclusively R1b, and pre-Yamnaya Eneolithic Volga-Caspian-Caucasus steppe men were principally R1b, with a significant Q1a minority.

Since the only available samples from the Khvalynsk community are R1b (x3), Q1a(x1), and R1a(x1), it seems strange that Anthony would talk about a “significant minority”, unless Q1a will pop up in some more individuals of those ca. 30 new to be published. Because he also mentions I2a2 as appearing in one elite burial, it seems Q1a (like R1a-M459) will not appear under elite kurgans, although it is still possible that hg. Q1a was involved in the expansion of Afanasevo to the east.

middle-bronze-age-y-dna
Y-DNA haplogroups in West Eurasia during the Middle Bronze Age. See full map and see maps of cultures, ADMIXTURE, Y-DNA, and mtDNA of the Middle Bronze Age and the Late Bronze Age.

Okunevo, which replaced Afanasevo in the Altai region, shows a majority of hg. Q1a2-M25, and at least one Q1a1-B284, but also some R1b-M269 samples proper of Afanasevo, suggesting partial genetic continuity.

NOTE. Other sampled Siberian populations clearly show a variety of Q subclades that likely expanded during the Palaeolithic, such as Baikal EBA samples from Ust’Ida and Shamanka with a majority of Q1a2-M25 (in particular Q1a2-L712), and hg. Q reported from Elunino, Sagsai, Khövsgöl, and also among peoples of the Srubna-Andronovo horizon (the Krasnoyarsk MLBA outlier), and in Karasuk. Q1a-M25 was earlier found in a Baltic hunter-gatherer, which supports a widespread distribution of Q1a2 and Q1a1 in North Eurasia during the Neolithic and Bronze Age.

From Damgaard et al. Science (2018):

(…) in contrast to the lack of identifiable admixture from Yamnaya and Afanasievo in the CentralSteppe_EMBA, there is an admixture signal of 10 to 20% Yamnaya and Afanasievo in the Okunevo_EMBA samples, consistent with evidence of western steppe influence. This signal is not seen on the X chromosome (qpAdm P value for admixture on X 0.33 compared to 0.02 for autosomes), suggesting a male-derived admixture, also consistent with the fact that 1 of 10 Okunevo_EMBA males carries a R1b1a2a2 Y chromosome related to those found in western pastoralists. In contrast, there is no evidence of western steppe admixture among the more eastern Baikal region region Bronze Age (~2200 to 1800 BCE) samples.

This Yamnaya ancestry has been also recently found to be the best fit for the Iron Age population of Shirenzigou in Xinjiang – where Tocharian languages were attested centuries later – despite the haplogroup diversity acquired during their evolution, likely through an intermediate Chemurchek culture (see a recent discussion on the elusive Proto-Tocharians).

Haplogroup diversity seems to be common in Iron Age populations all over Eurasia, most likely due to the spread of different types of sociopolitical structures where alliances played a more relevant role in the expansion of peoples. A well-known example of this is the spread of Akozino warrior-traders in the whole Baltic region under a partial N1a-VL29-bottleneck associated with the emerging chiefdom-based systems under the influence of expanding steppe nomads.

early-iron-age-y-dna
Y-DNA haplogroups in West Eurasia during the Early Iron Age. See full map and see maps of cultures, ADMIXTURE, Y-DNA, and mtDNA of the Early Iron Age and Late Iron Age.

Surprisingly, then, Proto-Tocharians from Shirenzigou pack up to 74% Yamnaya ancestry, in spite of the 2,000 years that separate them from the demise of the Afanasevo culture. They show more Yamnaya ancestry than any other population by that time, being thus a sort of Late PIE fossils not only in their archaic dialect, but also in their genetic profile:

shirenzigou-afanasievo-yamnaya-andronovo-srubna-ulchi-han

The recent intrusion of Corded Ware-like ancestry, as well as the variable admixture with Siberian and East Asian populations, both point to the known intense Old Iranian and Old/Middle Chinese contacts. The scarce Proto-Samoyedic and Proto-Turkic loans in Tocharian suggest a rather loose, probably more distant connection with East Uralic and Altaic peoples from the forest-steppe and steppe areas to the north (read more about external influences on Tocharian).

Interestingly, both R1b samples, MO12 and M15-2 – likely of Asian R1b-PH155 branch – show a best fit for Andronovo/Srubna + Hezhen/Ulchi ancestry, suggesting a likely connection with Iranians to the east of Xinjiang, who later expanded as the Wusun and Kangju. How they might have been related to Huns and Xiongnu individuals, who also show this haplogroup, is yet unknown, although Huns also show hg. R1a-Z93 (probably most R1a-Z2124) and Steppe_MLBA ancestry, earlier associated with expanding Iranian peoples of the Srubna-Andronovo horizon.

All in all, it seems that prehistoric movements explained through the lens of genetic research fit perfectly well the linguistic reconstruction of Proto-Indo-European and Proto-Uralic.

Related

Bronze Age cultures in the Tarim Basin and the elusive Proto-Tocharians

andronovo-xiaohe-horizon

Master’s thesis Shifting Memories: Burial Practices and Cultural Interaction in Bronze Age China: A study of the Xiaohe-Gumugou cemeteries in the Tarim Basin, by Yunyun Yang, Uppsala University, Department of Archaeology and Ancient History (2019).

Summary excerpts, mainly from the conclusions (emphasis mine):

Both the Xiaohe and the Gumugou groups are suggested as possibly originating from southern Siberia or Central Asia and being related to Afanasievo and Andronovo people (Han 1986, 1994; Li et al. 2010, 2015). But a latest research suggest that the Xiaohe males are genetic distinct from the Afanasievo males, considering the paternal lineages (Hollard et al. 2018). From genetic evidence, it is suggested that southern Siberia and Central Asia were dominated by Europeans during the Bronze Age. Southern Siberia was predominant by Europeans since the Bronze Age as a result of eastward migration of Kurgan people (Keyser et al. 2009). Central Asia started to have an eastern Eurasian maternal lineage that coexisted with the previous western maternal lineage from around 700 BCE (Lalueza-Fox et al. 2004). Based on the research mentioned above, we can conclude as that the Xiaohe and the Gumugou people possibly came from the southern Siberia or Central Asia.

Origin of the Xiaohe horizon

There are two hypotheses about the origins of the Xiaohe horizon. The “steppe hypothesis” assumes that the early settlers (Gumugou people) of the Tarim Basin came from the Afanasievo culture in the Minusinsk Basin-Altai Mountains regions (Kuz’mina et al. 2008; Mallory et al. 2008). The “oasis hypothesis” argues that the early settlers were related to the spreading of the oasis-based agricultural groups from the Bactria and Margiana parts of the southern Central Asia area (Chen et al. 1995). Both hypotheses mainly relied on the use of some materials such as animal cattle, sheep/goats, camel hair, and plant wheat, whose origins were bound to western traditions. But these proofs cannot provide enough support to claim that the Xiaohe horizon cultures were from Afanasievo or BMAC cultures, except for telling there were possible cultural connections or interactions among them. What’s more, there were no horses or potteries in the Xiaohe horizon.

It is worth noting that Ephedra plant is commonly thought as a strong candidate of the Soma or Haoma sacred drink for the ancient Indians or Iranians. Soma is the name recorded in the Vedic Brahmanism religious literature Rigveda, Haoma in the Zoroastrianism Avesta, and indicates as a ritual drink from plant juice. The reason to address Ephedra plant to Soma-Haoma drink is mainly because of its ephedrine, which works on muscle strength, low blood pressure, (and asthma) to make people get rid of tiredness (Houben 2013). Furthermore, it is thought that Ephedra with anti-fatigue function gives gods or the dead immortality, longevity, and resurrection (Mahdihassan 1987). From a mobile consideration of Vedic Aryans perspective, it is thought Vedic Aryans made use of Ephedra, cannabis and poppy to produce Soma drink in Margiana, only Ephedra in Bactria and in Indian mountains area, but other substitutes in Indian plains (Shah 2014). From the Ephedra perspective, it is agreeable that the Xiaohe-Gumugou people were related to the Indo-Aryan peoples (Mallory et al. 1997; Wang 2017).

gumugou-xiaohe
The distribution map of the sites in the Xiaohe cultural horizon.

Burial customs

Both the Xiaohe and the Gumugou groups maintained similar burial customs, but we can distinguish a developing process from the slight diverse ways of the Gumugou cemetery to the highly consistent and advanced technology in making coffins of the Xiaohe cemetery. In terms of the dressing, the dead wore a felt cap, a pair of leather boots, a bracelet twined on the right wrist, and was wrapped in a big felt mantle. The dead in the Xiaohe cemetery also wore a loin-cloth. Commonly, both cemeteries contained burials goods of Ephedra twigs, grains of wheat and millet, grass-made baskets, animal ears (such as calf ears), and livestock. Wooden coffins in the two cemeteries were constructed in a similar way, by assembling two side-planks, two end-boards, a lid consisting of a few short straight boards, and covered with livestock hide (mainly cattle hide in the Xiaohe cemetery and sheep/goats hide in the Gumugou cemetery).

Considering the similar and continuous burial behaviours in the two cemeteries, it can be assumed that both the Xiaohe and the Gumugou societies were stable and consistent. The Xiaohe cemetery had both the special clay-lid wooden coffins and the normal coffins in its early phase (burial layers 4th-5th), then turned to be stable and consistent with the normal coffins (burial layers 1st-3rd), and have developed better construction of the boat-shape coffins. The Gumugou cemetery contained two main burial patterns, type I; the sun-radiating-spokes burials and type II; the normal burials, which coexisted during the same time. Burials of type II were similar but not limited to strict rules. Burials in both the Xiaohe and the Gumugou cemetery were fairly heterogeneous, and the clay-lid wooden coffins in the Xiaohe cemetery and the sun-radiating-spokes burials in the Gumugou cemetery only took up in a small percentage of each cemetery. These special burial types could indicate special roles of the dead in their related societies. Either the dead had high social positions or possibly they actually had a different ancestry origin. It is argued here that the latter is something that is quite possible, considering the mixed populations in the two cemeteries.

The sun-radiating-spokes burials share some features with a similar type of grave, constructed of circular stone kerbs of the stone-pit graves. The sun-radiating-spokes burials might represent an adaption to the local desert environment, which had better access to wood rather than stones. Circular stone kerbs with stone-pit in centre were widely seen in Bronze Age Afanasievo and Andronovo burials, and also in the late Bronze Age and early Iron Age burials along the Tian Shan. The present study suggests a high possibility that the six males buried in the sun-radiating-spokes graves came from the contemporary parallel Andronovo horizon, and kept some of their own ancestry memories in an adapted way.

xinjiang-afanasievo-andronovo-bmac-tian-shan
An assumption of the spreading/expansion routes stone burial construct.

Societies

Although the Xiaohe and Gumugou societies were stable and consistent, it does not mean that the societies were isolated, and we can see strong indications of them being open to the outside. With time, the Xiaohe population were getting even more diverse origins, as newcomers kept joining the group from outside. However, the burial behaviours in the Xiaohe cemetery did not change as a consequence if these additions. This suggests that the newcomers inherited the local burial customs, and strongly indicates that they became part of the community and adopted the new social identity, possibly through marriage. As a result, the diverse populations can well explain the coexistence of different cultural elements in the burials, e.g. cattle, sheep/goats, camel hair (from Central Asia), grains of wheat (from the west) and millet (from the east), etc.

The Xiaohe and the Gumugou societies were similar, but the Xiaohe society developed to a more advanced level both in economy and in social structure. First, the oasis-based economic system of the Xiaohe and the Gumugou had similar husbandry, but later this was developed to different extent. Both societies mainly relied on livestock, and while the Xiaohe people favoured cattle, the Gumugou people favoured sheep/goats. The two societies also developed agriculture, which can be seen from the grains of wheat and millet. It has been shown that grains of wheat are bread wheat. The Xiaohe people also cooked porridge with millet and milk, and had dairy products.

From these evidences, we can assume that the Xiaohe people have developed a stronger economic level. Secondly, the Xiaohe society had more distinguished gender roles, resulting in different social roles for men and women in terms of work and religions. The female and male dead were buried in a distinguished way with loin-cloths and wooden monuments. Sexual identity on a social level refers to how people consider and expect different genders to act and behave under the social and cultural framework. In the Xiaohe society, men carried out hunting tasks (creatures like vultures, badgers, lizards, snakes); women were associated to the rebirth of lives. To synthesize, a possible relation between the Xiaohe and the Gumugou societies is that they represent two parallel groups who shared similar economic systems because of the similar environment, or that there is a chronological difference where the Gumugou people may have existed earlier. The absolute dating information from the two cemeteries is insufficient to rule out the second situation.

tarim-basin-regions
The area division of the Tarim Basin and its surroundings (The division is made based on the mountain ranges including Altai Mountains, Tian Shan, and Kunlun Mountains, and also the distribution of ancient cemeteries in the whole Xinjiang generally.)

Surroundings

To place the Xiaohe horizon in the larger context of the Bronze Age burials in its surroundings, the hypothesis presented in this study is that the Xiaohe-Gumugou people might possibly represent a parallel to the Andronovo groups, with an eastward migration, that developed their own societies and ethnicities in the Tarim Basin with some ancestral memories still preserved. Considering the location and the geographical features of Xinjiang, the Altai Mountains and the Tian Shan left open access from the Eurasian Steppe to the Dzungarian Basin. The Hami Basin-the Balikun Grassland was the first intersection area to combine the possible western and eastern cultural influences. To pass by the Turpan Basin and enter into the Tarim Basin, there were two possible routes, one northern route along the southern edge of Tian Shan, and one southern route along the northern edge of Kunlun Mountains.

In the early Bronze Age, the burials in Xinjiang had some clear typical geographic features that distinguish them from their surroundings. But from the late Bronze Age to the early Iron Age, the tradition with circular kerbs of stones with stone-pits burials expanded along the southern edge of the Tian Shan, which was a major shift of burial practice that possibly could be linked to the expansion of the Andronovo horizon or a general nomadic expansion.

Although there were no horses or wagons found in the Xiaohe burials, the wooden horse-hoof objects were an indication of horses, which did not exist in their daily lives anymore, but possibly were related to some settlers’ ancestral memories of their nomadic origins. However, it was more important for them to assimilate to the common social identities of their new group. After people died, it was preferred to be buried in the communal cemetery. Even if the dead bodies were lost, wooden substitutes will be used in graves to represent the dead, since they believed in afterlife and thought that the end of the death is rebirth.

Comments

While the results of Li et al. (2010, 2015) of Xiaohe mummies regarding Y-chromosome haplogroups – showing mostly R1a(xZ93) – and radiocarbon dates of the samples are yet to be confirmed, Proto-Tocharians are known to have had contacts with Samoyeds, early Indo-Iranians (in turn in contact with the BMAC language), then into Common Tocharian with ancient Iranians, and then Indo-Aryan and Iranian languages again (for more on this, see Ged Carling‘s publications).

The connection of the Tocharian branch with Afanasevo is essentially indisputable today, like that of Late Proto-Indo-European with late Repin/early Yamna, even more so than it was just 10 years ago, thanks to the most recent genetic investigation. The common genetic stock of Yamna and Afanasevo – as well as that of East Bell Beakers and Palaeo-Balkan peoples – fits perfectly earlier predictions based on the linguistic estimates of the separation and evolution of the diverse language communities, and the tentative attribution to Eurasian steppe-related cultures.

early-bronze-age-tocharian-chemurchek
Tentative identification of language groups among Early Bronze Age cultures. Pre-/Proto-Tocharian is traditionally associated with Chemurchek. See full image.

The trail leading from Afanasevo to Common Tocharians, on the other hand, seems to be more tricky, not unlike many other Indo-European-speaking groups from Europe and Asia, whose precise evolution until their historical attestation is often unclear. Nevertheless, the eventual presence of diverse haplogroups among historical Tocharians – whether they coincide with ancient DNA recovered from BMAC, South India, Andronovo, or Bronze Age Tian Shan populations – will only be relevant to understand the genetic evolution of the speakers of Tocharian during its different stages.

If the genetic trail backwards from known Tocharians to (earlier) unknown Common Tocharians, and forwards from known Pre-Tocharians to (later) unknown Proto-Tocharians leads unequivocally to these populations from the Xiaohe cultural horizon, this paper shows one of the mechanisms through which peoples of the Andronovo cultural horizon (or, more precisely, male lines derived from it) may have become integrated into a Tocharian-speaking population, not dissimilar to what happened in the steppes between Uralic-speaking Abashevo and Pre-Proto-Indo-Iranian-speaking Catacomb-Poltavka to form the Proto-Indo-Iranian-speaking Sintashta-Potapovka-Filatovka culture.

As we have discussed in this blog many times over, to solve this ethnolinguistic identification of prehistoric cultures one needs to investigate ancient DNA in combination with linguistic guesstimates and the Indo-European homeland problem from a wide anthropological perspective. People not understanding this simple concept are bound to end up in some comical Tocharo-Indo-Iranian grouping related to Corded Ware ancestry from Andronovo, similar to the Celto-Ibero-Basques of elevated CEU BA ancestry and hg. R1b-P312 to the south of the Pyrenees during the Iron Age from Olalde et al. (2019), and to the Balto-Finno-Slavs of hg. R1a-Z283 and elevated “Steppe ancestry” in the BA-IA East Baltic from Saag et al. (2019)

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