Trypillia and Greece Neolithic outliers: the smoking gun of Proto-Anatolian migrations?

neolithic-migrations-khvalynsk-novodanilovka-anatolian

(Continued from the post Corded Ware culture origins: The Final Frontier).

Looking at the PCA of Wang et al. (2018), I realized that Sredni Stog / Corded Ware peoples seem to lie somewhere between:

  • the eastern steppe (i.e. Khvalynsk-Yamna); and
  • Lower Danube and Balkan cultures affected by Anatolian- and steppe-related (i.e. Khvalynsk-Novodanilovka) migrations.

This multiethnic interaction of the western steppe fits therefore the complex archaeological description of events in the North Pontic, Lower Danube, and Dnieper-Dniester regions. Here are some interesting samples related to those long-lasting contacts:

1. I3719 (mtDNA H1, Y-DNA I2a2a) Ukraine Neolithic sample from Dereivka ca. 4949–4799 BC, described in Mathieson et al. (2018) as of “entirely northwestern-Anatolian-Neolithic-related ancestry”.

2. ANI163 from Varna I ca. 4711–4550 BC (mtDNA H7a1), and I2181 from Balkans Chalcolithic (Smyadovo, in Bulgaria) ca. 4500 BC (mtDNA HV15, Y-DNA R) show the first steppe ancestry in regions known to be affected by the expansion of Suvorovo chiefs.

3. The Yamna Bulgaria outlier (Y-DNA I2a2a1b1b), 3012-2900 calBCE, shows apparently an admixture with cultures of that region (but 1,500 years later).

PCA-trypillia-greece-neolithic-outlier-anatolian
Image modified from Wang et al. (2018). Samples projected in PCA of 84 modern-day West Eurasian populations (open symbols). Previously known clusters have been marked and referenced. Marked and labelled are the Balkan samples referenced in this text An EHG and a Caucasus ‘clouds’ have been drawn, leaving Pontic-Caspian steppe and derived groups between them. See the original file here.

Trypillia and Corded Ware

4. There is one ‘Trypillia outlier’ among five samples from the Verteba cave in Wang et al. (2018): I1927 (Y-DNA G2a2b2a1a1b1a1a1, mtDNA H1b), ca. 3619-2936 BC, a sample published previously in Nikitin et al. (2017) and Mathieson et al. (2017). We were very quick to dismiss Trypillia (three samples of haplogroup G2a, one sample E) and GAC as a source of Corded Ware admixture, but archaeology clearly shows important population movements at the end of the fourth millennium between late Trypillia groups, GAC, and post-Sredni Stog populations, and genetics is showing that in both cultures, too.

I am not a fan of the ‘lack of samples’ argument, but (similar to Old Hittite samples related to all Anatolian speakers) one site is not enough to describe a culture that spanned millennia and many different early and late groups. One among five Trypillian samples (from a single site), showing a late date (ca. 3228 BC) compared to the other samples (ca. 3700 BC), and quite close to the only three Ukraine Eneolithic samples we have may mean much more than what we may a priori think, i.e. some simplistic unidirectional punctual ‘intrusion’ of steppe ancestry, and instead hint at the known close contacts of late Trypillian groups and North Pontic cultures, including also the Caucasus.

NOTE. The big difference in PCA among GAC-like Hungary LCA – EBA samples (see above two star symbols close to Ukraine Neolithic outlier in the PCA, in contrast with the other three at the bottom) may also be significant, although we don’t have any data about their culture, sites, or the relationship between them.

trypillia-verteba-cave
Location of Verteba Cave in relation to different stages and neighbouring groups of the Cucuteni-Trypillia culture. Image from the paper A Subterranean Sanctuary of the Cucuteni-Trypillia Culture in Western Ukraine, by Kadrow and Pokutta (2016).

Greece Neolithic outlier: Proto-Anatolians?

5. Especially interesting is I6423, one of the Greece Neolithic samples referred to in Wang et al. (2018), which is obviously an outlier among the three used in the paper. It does not seem to correspond to any of the ancient DNA samples published to date; it is not in Hofmanova et al. (2016), in Lazaridis et al. (2017), or in Mathieson et al. (2018).

Since the Neolithic in Greece could mean any period from ca. 6500 BC to ca. 3200 BC, I guess we are talking here about some migration related to the expansion of Khvalynsk-Novodanilovka chieftains after ca. 4500 BC, because it appears on the PCA precisely on the same spot as Varna and Smyadovo outliers, and its ADMIXTURE shows similar components

admixture-ukraine-eneolithic-greece-neolithic
Image modified from Wang et al. (2018). “ADMIXTURE results of relevant prehistoric individuals mentioned in the text (filled symbols)”. ‘Outlier’ samples referred to in this post have been marked in red. See the original file here.

So, this may be the smoking gun of Proto-Anatolian (or maybe early Common Anatolian) expansion with steppe migrants up to the border of Western Anatolia, and we may be able to get rid of those unfounded doubts about Anatolian origins once and for all…

NOTE. Also interesting seems another Greece Neolithic sample, I6420, in ADMIXTURE, although its position in the PCA (near Minoans and Mycenaeans) does not necessarily point to potential steppe influence, but rather to the extra ‘eastern (Caucasus/Iran-related) ancestry’ contribution found in Minoans and in Mycenaeans (and Anatolia Chalcolithic) compared to previous samples of the region. The third Greece Nelithic sample, I5427 (mtDNA K1a24), from Diros, Alepotrypa Cave, is dated 6005-5879 BC (mean 5892 BC), and appeared first in Mathieson et al. (2018).

greece-neolithic
Modified from Wang et al. (2018) (Greece_Neolithic in red). Supplementary Table 6. P values of rank=1 in modelling the two-way admixture in the Caucasus cluster. 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. Source 2 populations in bold print are used as examples in modelling the Caucasus cluster groups (See Supplementary Table 7).
greece-neolithic-caucasus
Modified from Wang et al. (2018) (Greece_Neolithic in red). Supplementary Table 10. P values of rank=2 and ancestry proportions in modelling a three-way admixture in the Caucasus cluster testing additional contribution from Iran_ChL. Here, we used an extended set of outgroup populations populations to constrain standard errors: 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, EHG, WHG, Levant_N.

If this Greece Neolithic sample is not related to Yamna migrations – and its use for statistical analysis of Caucasus samples from Wang et al. (2018) suggests that it is not – , it may have important consequences:

If it is located near the Western Anatolian coast – especially near Troy – there won’t be much to add about the potential site of entry of Common Anatolian languages into Anatolia… I have read some comments about how ‘impossible’ it was for steppe migrants and their language to ‘invade’ the more advanced cultures of Anatolia from the west, but it seems as ‘impossible’ as it was for Barbarians to invade the Roman Empire and impose their language as elites in certain regions. (And yes, we have at least one important weak political period among Middle Eastern cultures in the early 3rd millennium BC, similar to the period of the Fall of the Western Roman Empire).

indo-european-anatolian-uralic-migrations
Most likely Proto-Anatolian expansion in the North Pontic and Balkan area with Khvalynsk-Novodanilovka chieftains, including ADMIXTURE data from Wang et al. (2018).

If it is located somewhere more ‘central’ in the Greek Peninsula, then it could also be used to support the Anatolian nature of the controversial Pre-Greek (‘Pelasgian’) substrate. While we know that Greek (at least since Mycenaean) shows a strong Pre-Greek cultural and linguistic heritage (also reflected in its genetic continuity), the nature of that language is usually believed to be non-Indo-European, and Anatolian contacts are rather few and coincident with the Mycenaean period. I don’t think this sample can tell much about the Pre-Greek language, though, because – if it is really Neolithic, and comparing it with later Minoan and Mycenaean samples – it seems a clear outlier.

suvorovo-novodanilovka-expansion-europe
Heyd (2016): The Southeast European distribution of graves of the Suvorovo-Novodanilovka group and such unequipped ones mentioned in the text which can be attributed by burial custom and stratigraphic position in the barrow, plus zoomorphic and abstract animal head sceptres as well as specific maceheads with knobs as from Decea Maresului (mid-5th millennium until around 4000 BC). The site in the south-west Balkans is Suvodol-Šuplevec, Northern Macedonia (FYROM).

If it is, however, related to later Yamna migrations after ca. 3000 BC (and, like the ‘Ukraine Eneolithic’ sample that is likely from Catacomb, it is classified as Neolithic just because it cannot be attributed to precise Helladic periods), then we may be in front of the first obvious Yamna migrants in Greece. If that is the case (which I doubt), the sample wouldn’t be so informative for PIE dialectal expansions, because by now it is evident that we will find steppe ancestry and R1b-Z2103 subclades accompanying Yamna migrants in the southern Balkans, and probably well into Mycenaean Greece.

NOTE. Whatever the case, I am sure that for those fond of absurd autochthonous continuity theories, as well as for anti-steppe conspirationists, this sample will be just another good way of arguing for anything, ranging from a rejection of the Middle PIE – Late PIE division, to a support for some mythic ancient autochtonous Proto-Graeco-Anatolian group, or maybe some ancient Graeco–Indo-Slavonic split, or whatever new dialectal stage one can invent to support the own genealogical fantasies…

So, if it actually is a Neolithic sample, let’s hope that it shows a clear R1b-M269 (xL23 or early L23) subclade distinct from those (likely Z2103) expanded later with Late PIE-speaking Yamna (and probably to be found among Mycenaeans), so that there can be no more place for ethnic fantasies.

EDIT (28 JUL 2018): Added information on Greece Neolithic and Trypillia samples

Related

Corded Ware culture origins: The Final Frontier

corded-ware-yamna-bell-beaker

As you can imagine from my latest posts (on kurgan origins and on Sredni Stog), I am right now in the middle of a revision of the Corded Ware culture for my Indo-European demic diffusion model, to see if I can add something new to the draft. And, as you can see, even with ancient DNA on the table, the precise origin of the Corded Ware migrants – in spite of the imaginative efforts of the Copenhagen group to control the narrative – are still unknown.

Corded Ware origins

The main objects of study in Corded Ware origins are necessarily the region where the oldest Corded Ware vessels appeared, Lesser Poland, as well as the adjacent (traditionally considered Proto-Corded Ware regions) Volhynia, Podolia, and upper Dniester river basin. These are some relevant points, continuing where I left the Eneolithic steppe developments (following Szmyt 1999, Rassamakin 1999, Kadrow 2008, Furholt 2014):

gac-trypillia-yamna-usatovo
Kadrow (2008). Cultural interactions around Carpathians at the beginnings of the 3rd millennium BC: 1 – Globular Amphora culture; 2 – Sofievka group of Trypillia culture; 3 – Funnel Beaker culture; 4 – Baden culture; 5 – Kostolac culture; 6 – Coţofeni culture; 7 – Cernavoda II culture; 8 – Yamnaya culture and Usatovo group of Trypillia culture (apud Kadrow, 2001).
  • More frequent contacts were seen ca. 3500-3000 BC, with an interaction showing multidirectional migrations of larger human groups in the centuries around 3000 BC, involving a significant part of the population of central-east Europe.
  • The easternmost area of the Funnel Beaker culture had become more Baden-like with the expansion of the Baden culture in its western area ca. 3300-2900 BC (with findings up to 2600 BC), and these younger groups with Baden features moved increasingly into the western part of Volhynia.
  • The influence of the neighbouring Trypillian culture is seen in the eastern parts of Volhynia, from ca. 3000 BC, either from a younger phase CII (cf. Troyaniv, Koshilivtsy, Brînzeni, Zhvaniets, or Vychvatintsy) or later groups (cf. Gorodsk, Kasperivtsy, Sofievka, Horodiştea-Folteşti, Usatovo).
  • In the forest-steppe zone, herding and hunting activities intensified, while agricultural traditions were preserved, as shown by the Sofievka, Kasperivtsy, and Gorodsk groups. From the end of the 4th millennium BC mobile parts of the late Trypillian populations moved to the steppe zone, absorbing more and more steppe elements; among others, cord ornamentation (in Vykhvatintsy, Troyaniv, and Gorodsk groups), pottery forms (Vykhvatintsy, which served as prototype for the Thuringian Apmphorae, dispersed along the Dniester river, too), flat burials with bodies in contracted position on the left or right side (Vykhvatintsy, reminding of Polgár culture different male-female position, and later Corded Ware burials, and also Lower Mikhailovka, under a mound without stone constructions). At the end of the Trypillia culture, its agricultural system collapsed completely.
gac-trypillia-usatovo-corded-ware
Globular Amphorae culture „exodus” to the Danube Delta: a – Globular Amphorae culture; b – GAC (1), Gorodsk (2), Vykhvatintsy (3) and Usatovo (4) groups of Trypillia culture; c – Coţofeni culture; d – northern border of the late phase of Baden culture;red arrows – direction of Globular Amphora culture expansion; blue arrow – direction of „reflux” of Globular Amphora culture (apud Włodarczak, 2008, with changes).
  • Slash and burn techniques of agriculture – especially those practiced by Trypillian and Funnel Beaker populations – must have intensified effects of natural growth of humidity (ca. 3400-2400), increasing fluvial activities in west Ukrainian river valleys, and increasing deforestation processes, which favoured pastoralism and nomadisation of the settlement system, and a consequent change of the social structure
  • At the same time, Yamna communities expanded along the lower and central Danube to the west, while the populations of the late phase of the Baden culture took the opposite direction and reached as far as Kiev in the north-east, contributing to the culture of the Sofievka group.
  • Globular Amphora communities migrated from the north-west, from eastern Poland, towards the Danube Delta and as far as the Dnieper in the east, destroying the primary structures of the communities in the supposed cradle territories of the Corded Ware culture. These communities found refuge and conditions for further development in south-eastern margin zone of the Funnel Beaker culture territories, penetrating at first the upper parts of the loess uplands like typical Funnel Beaker sites, but on the margins of their range, and also on areas avoided by Funnel Beaker settlement agglomerations. They brought with them the so-called Thuringian amphora up to Lesser Poland, borrowed from the late Trypillian Usatovo group. This resulted in the Złota culture, which eventually gave rise to the A-Amphorae.
funnelbeaker-trypillia-corded-ware
Map of territorial ranges of Funnel Beaker Culture (and its settlement concentrations in Lesser Poland), local Tripolyan groups and Corded Ware Culture settlements (■) at the turn of the 4th/3rd millennia BC.

In the end, we are left with this information about the oldest CWC (Furholt 2014):

  • The earliest radiocarbon-dated groups associated with the Corded Ware culture come from new single graves from Jutland in Denmark and Northern Germany, ca. 2900 BC. This Early Single Grave culture is associated with the appearance of individual graves (some time after the decline of the megalithic constructions), composed of a small round barrow and a new gender-differentiated burial practice emphasising male individuals orientated west-east (with regional exceptions), combined with the internment with new local battle-axe types (A-Axe). However, there is no single type of burial or burial custom in Corded Ware:
    • In southern Sweden the prevailing orientation is north-east – south-west, and south-north, contrary to the supposed rule male individuals are regularly deposited on their left and females on their right side.
    • In the Danish Isles and north-eastern Germany, the Final Neolithic / Single Grave Period is characterized by a majority of megalithic graves, with only some single graves from typical barrows. In south Germany, west-east and collective burials prevail, while in Switzerland no graves are found.
    • In Kujawia (south-eastern Poland), Hesse (Germany), or the Baltic, west-east orientation and gender differentiation cannot be proven statistically.
corded-ware-regions-main
Furholt (2014). Map of the Corded Ware regions of central Europe. The dark shading indicates those regions where Corded Ware burial rituals are present regularly
  • The oldest Corded Ware vessels (the A-Amphorae, which define the A-Horizon of the CWC) come probably from the Złota (or a related) group in Lesser Poland, where a mixed archaeological culture connecting Funnel Beaker, Baden, Globular Amphorae and Corded Ware appears ca. 2900-2600 BC. No cultural (typological) break is seen between earlier Globular Amphorae and the first Corded Ware Amphorae, but rather a continuum of traits and characteristics among the recovered vessels. This strengthens the connection of Corded Ware with Globular Amphorae peoples. The A-horizon expanded thus probably from Lesser Poland ca. 2800-2600, as seen in local contexts.
  • And of course we have a third way of defining Corded Ware individuals, which is the presence of herding, and thus a transition from hunter-gatherers to agropastoralists. This is how some Baltic Late Neolithic individuals with no archaeological data have been classified as members of the Corded Ware culture: Even though no cultural remains were extracted with the two ‘outlier’ individuals, their haplogroup and ancestry point to a direct origin in or around the steppe and forest-steppe region (yes, that risks circular reasoning).
globular-amphorae-corded-ware-zlota-amphorae
Correspondence analysis of amphorae from the Złota-graveyards reveals that there is no typological break between Globular Amphorae and Corded Ware Amphorae, including ‘Strichbündelamphorae’ (after Furholt 2008)

Corded Ware peoples in genetics

So, no clear origin of Corded Ware migrants, a lot of data pointing to intense migrations and interaction among GAC, Trypillia and the western steppe population (remember Kristiansen’s ‘long-lasting GAC-CWC connection’, now ignored to favour their Yamnaya admixture™ concept), and also three ways of defining Corded Ware culture…

Maybe genetics can help:

Ukraine Neolithic cultures – mainly from Dereivka – show haplogroups R1b-V88, R1a1, and R1b-L754 (xP297, xM269), which is similar to the haplogroup distribution found in Ukraine Mesolithic, but apparently with an expanding group marked by haplogroup I2a2a1b1 (possibly I2a2a1b1b).

The first thing that stands out about Ukraine Eneolithic samples is that only two of them can be said to be really Ukraine Eneolithic (i.e. from “Sredni Stog”-related groups):

  • I5876 (Y-DNA R1a-Z93(Y3+), mtDNA U5a2a), from Alexandria, 4045-3974 calBCE (5215±20BP, PSUAMS-2832)
  • I4110 (mtDN AJ2b1), from Dereivka, 3634-3377 calBCE (4725±25 BP, UCIAMS-186349), J2b1

The other two samples are quite late, and in fact one of them is clearly too late (maybe from the Catacomb culture):

  • I5882 (mtDNA U5a2a), from Dereivka, 3264-2929 calBCE (4420±20BP, PSUAMS-2826)
  • I3499 (Y-DNA R1b-Z2103, mtDNA T2e), from Dereivka, 2890-2696 calBCE (4195±20BP, PSUAMS-2828)

Corded Ware samples from Mittnik et al. (2018) offer very wide radiocarbon dates, so it is unclear which of them may be the oldest one. Most of them cluster closely to the older Ukraine Eneolithic sample I5876, but also to later steppe_MLBA samples i.e. Sintashta, Potapovka, and especially Srubna and Andronovo). This points to a genetic continuity from Pre-Corded Ware to Classic and late Corded Ware peoples. Therefore, much like Khvalynsk-Yamna and apparently many other Neolithic cultures, these peoples did not really admix; at least not with the male population.

pca-mittnik-late-neolithic
File modified by me from Mittnik et al. (2018) to include the approximate position of the most common ancestral components, and an identification of potential outliers. Zoomed-in version of the European Late Neolithic and Bronze Age samples. “Principal components analysis of 1012 present-day West Eurasians (grey points, modern Baltic populations in dark grey) with 294 projected published ancient and 38 ancient North European samples introduced in this study (marked with a red outline).

Lucky for us, even though the culture remains undefined, haplogroup R1a-Z645 seems like a unifying trait, as I said long ago, so we only have to wait for more samples to trace their origin. Nevertheless, it is clear that Corded Ware may not have been as genetically homogeneous as Khvalynsk, Yamna and Yamna-related cultures, further supporting its archaeological complexity:

  • Jagodno1 and Jagodno2 (Silesia), dated ca. 2800 BC, show haplogroup G? and I/J? – compatible with an origin of CWC in common with Trypillia (which shows 3 samples of haplogroup G2a2b2a, and one E) and Ukraine Neolithic (showing the expansion of I2a2a1b1 subclades).
  • I7272, from Brandýsek (Czech Republic), dated ca. 2900-2200 BC shows haplogroup I2a2a2 (compatible with an origin in Ukraine Neolithic peoples – this haplogroup is also found in Yamna Kalmykia and in the Yamna Bulgaria outlier, i.e. late western samples from the Early Yamna culture).

NOTE. This precise subclade is only present to date in Chalcolithic samples from Iberia, which points (possibly like the Esperstedt family) to local Central European haplogroups integrated in a mixed Proto-Corded Ware population. The upper subclade I2a2a is found in Neolithic samples from Iberia, the British Isles, Hungary (Koros EN, ALPc), and also south-east European Mesolithic and Neolithic samples.

  • RISE1, from Oblaczkowo (Greater Poland), ca. 2865-2578 BC, shows haplogroup R1b1.
  • The Esperstedt family samples have been analysed as R1a-M417 (xZ645), although the supposed ‘xZ645’ has not been confirmed – not even in the risky new Y-calls from Wang et al. (2018) supplementary materials.
corded-ware-regions-network
Network analysis based on the quantitative occurrence of Corded Ware pottery forms, pottery ornamentation styles, tools,
weapons and ornaments as stated in Table 1, based on the catalogues given in Table 2, line thickness representing similarity

Maybe this heterogeneity is a problem of better defining the culture, but from what we can see the oldest CWC regions and the unifying ‘Corded Ware province’ – formed after ca. 2700 BC by Jutland and Northern Germany, the Netherlands, Saale, Bohemia, Austria and the Upper Danube regions – are for the moment not the most genetically homogeneous groups.

Homogeneity comes later – which we may tentatively identify with the expansion of the A-horizon from the northern Dnieper-Dniester and Lesser Poland area – , as seen around the Baltic (like the Battle Axe culture) with R1a-Z283 subclades, and around Sintashta (i.e. probably Abashevo – Balanovo) with R1a-Z93 subclades, which is compatible with the late spread of different Z645 groups (and potentially a unifying language) .

Related

The concept of “Outlier” in Human Ancestry (II): Early Khvalynsk, Sredni Stog, West Yamna, Iron Age Bulgaria, Potapovka, Andronovo…

yamna-corded-ware-bell-beaker

I already wrote about the concept of outlier in Human Ancestry, so I am not going to repeat myself. This is just an update of “outliers” in recent studies, and their potential origins (here I will repeat some of the examples):

Early Khvalynsk: the three samples from the Samara region have quite different positions in PCA, from nearest to EHG (of Y-DNA haplogroup R1a) to nearest to ANE ancestry (of Y-DNA haplogroup Q). This could represent the initial consequences of the second wave of ANE ancestry – as found later in Yamna samples from a neighbouring region -, possibly brought then by Eurasian migrants related to haplogroup Q.
With only 3 samples, this is obviously just a tentative explanation of the finds. The samples can only be reasonably said to show an unstable time for the region in terms of admixture (i.e. probably migration), judging by the data on PCA.

Ukraine Eneolithic samples offer a curious example of how the concept of outlier can change radically: from the third version (May 30th) of the preprint paper of Mathieson et al. (2017), when the Ukraine Eneolithic sample with steppe ancestry (and clustering with central European samples) was the ‘outlier’, to the fourth version (September 19th), when two samples with steppe ancestry clustering close to Corded Ware samples were now the ‘normal’ ones (i.e. those representing Ukraine Eneolithic population), and the outlier was the one clustering closely with Ukraine Mesolithic samples…

pca-admixture-yamna
PCA and Admixture for south-eastern Europe. Image modified from Mathieson et al. (2017) – Third revision (May 30th), used in the 2nd edition of the Indo-European demic diffusion model.

This is one of the funny consequences of the wrong interpretation of the ‘yamnaya component’, that made geneticists believe at first that, out of two samples (!), the ‘outlier’ was the one with ‘yamnaya’ ancestry, because this component would have been brought by an eastern immigrant from early Khvalynsk…

This example offers yet another reason why precise anthropological context is necessary to offer the right interpretation of results. Within the Indo-European demic diffusion model – based mainly on Archaeology and Linguistics – , the sample with steppe ancestry was the most logical find in the region for a potential origin of the Corded Ware culture, and it was interpreted as such, well before the publication of the fourth version of Mathieson et al. (2017).

pca-south-east-europe
PCA of South-East European and other European samples. Image modified from Mathieson et al. (2017) – Fourth revision (September 19th), used in the 3rd edition of the Indo-European demic diffusion model.

West Yamna (to insist on the same question, the ‘yamnaya’ component): we have only four western Yamna samples, two of them showing Anatolian Neolithic ancestry (one of them, from Ukraine, with a strong ‘southern’ drift). On the other hand, Corded Ware migrants do not show this. So we could infer that their migrations were not coetaneous: whereas peoples of Corded Ware culture expanded ca. 3300 BC to the north – in the natural corridor to the Baltic that has been proposed for this culture in Archaeology for decades (and that is well represented by Ukraine Eneolithic samples) -, peoples of Yamna culture expanded to the west, replacing the Ukraine Eneolithic population (i.e. probably those of ‘Proto-Corded Ware culture’), and eventually mixing with Balkan populations of Anatolian Neolithic ancestry.

Potapovka, Andronovo, and Srubna: while Potapovka clusters closely to the steppe, and Andronovo (like Sintashta) clusters closely to Corded Ware (i.e. Ukraine Neolithic / Central-East European), both have certain ‘outliers’ in PCA: the former has one individual clustering closely to Corded Ware, and the latter to the steppe. Both ‘outliers’ fit well with the interpretation of the recent mixture of Corded Ware peoples with steppe populations, and they offer a different image for the evolution of populations of Potapovka and Sintashta-Petrovka, potentially influencing their language. The position of Srubna samples, nearer to Sintashta and Andronovo (but occupying the same territory as the previous Potapovka) offers the image of a late westward conquest from Corded Ware-related populations.

asia-early-bronze
Diachronic map of migrations ca. 2250-1750 BC

Iron Age Bulgaria: a sample of haplogroup R1a-z93, with more ‘yamnaya’ ancestry than any other previous sample from the Balkans. For some, it might mean continuity from an older time. However – as with the Corded Ware outlier from Esperstedt before it – it is more likely a recent migrant from the steppe. The most likely origin of this individual is therefore people from the steppe, i.e. either the Srubna culture or a related group. Its relatively close cluster in PCA to certain recent Slavic populations can be interpreted in light of the multiple back and forth migrations in the region: of steppe populations to the west (Srubna, Cimmerians, Scythians, Sarmatians,…), and of Slavic-speaking populations:

middle-bronze-age-middle-east
Diachronic map of Bronze Age migrations ca. 1750-1250 BC.

Well-defined outliers are, therefore, essential to understand a recent history of admixture. On the other hand, the very concept of “outlier” can be a dangerous tool – when the lack of enough samples makes their classification as as such unjustified -, leading to the wrong interpretations.

Related:

The concept of “outlier” in studies of Human Ancestry, and the Corded Ware outlier from Esperstedt

pca-yamna-corded-ware

While writing the third version of the Indo-European demic diffusion model, I noticed that one Corded Ware sample (labelled I0104) clusters quite closely with steppe samples (i.e. Yamna, Afanasevo, and Potapovka). The other Corded Ware samples cluster, as expected, closely with east-central European samples, which include related cultures such as the Swedish Battle Axe, and later Sintashta, or Potapovka (cultures that are from the steppe proper, but are derived from Corded Ware).

I also noticed after publishing the draft that I had used the wording “Corded Ware outlier” at least once. I certainly had that term in mind when developing the third version, but I did not intend to write it down formally. Nevertheless, I think it is the right name to use.

pca-yamna-corded-ware
PCA of dataset including Minoans and Mycenaeans, and Scythians and Sarmatians. The graphic has been arranged so that ancestries and samples are located in geographically friendly axes similar to north-south (Y), east-west(X). Symbols are used, in a simplified manner, in accordance with symbols for Y-DNA haplogroups used in the maps. Labels have been used for simplification of important components. Areas are drawn surrounding Yamna, Poltavka, Afanasevo, Corded Ware (including samples from Estonia, Battle Axe, and Poltavka outlier), and succeeding Sintashta and Potapovka cultures, as well as Bell Beaker. Corded Ware sample I0104, from Esperstedt, has also been labelled.

Outlier in Statistics, as you can infer from the name, is a sample (more precisely an observation) that lies distant to others. It is a slippery concept in Human Evolutionary Biology, because it has no clear definition, and it is thus dependent on a certain degree of subjective evaluation. It seems to be mainly based on a combination of PCA and ADMIXTURE analyses, but should obviously be dependent on the number of samples available for a certain culture, and the regional distribution of the samples available.

We have thus certain clear cases, like the Poltavka outlier, of R1a-M417 lineage, clustering close to Corded Ware (and Sintashta, and Potapovka) samples, but far from other R1b-L23 samples from Poltavka or Yamna cultures, from neighbouring regions in the steppe.

We have also less clear observations, like Balkan Chalcolithic samples, which may or may not have been part of different cultural groups (say, related to the Suvorovo-Novodanilovka expansion, or not), which may justify their differences in ancestral components in ADMIXTURE, and in their position in PCA.

And we have a Yamna sample from western Ukraine, which – unlike the other two available samples – clusters “to the south” of east Yamna samples. Taking into account the Yamna sample from Bulgaria, clustering closely with south-eastern European samples, could you really call this an outlier? Two outliers out of four western Yamna samples? Well, maybe. If you take east and west Yamna from the steppe as a whole, and exclude the Yamna sample from Bulgaria, of course you can. Whether that classification is useful, or actually hinders a proper interpretation of western Yamna samples, and of the “Yamna component” seen in them, is a different story…

pca-yamna
PCA for European samples of Mathieson et al. (2017)

But what then about the Corded Ware male from Esperstedt, labelled I0104, dated ca. 2430 BC, which clusters among contemporaneous steppe (Poltavka) samples, and has the greatest proportion of ‘Yamna component’ in ADMIXTURE? After all, it is different in both respects from any other Corded Ware individual – including the oldest samples available, from Latvia (ca. 2885 BC) and Tiefbrunn (ca. 2755 BC).

This sample is one of the direct links between the steppe and Corded Ware in late times, and has been the main reason for the confusion a lot of people seem to have about the “Yamna component” in Corded Ware, with some supporting a direct migration from one into the other, and a few even daring to say that “Corded Ware is indistinguishable from Yamna”(!?).

His family members – all males of haplogroup R1a-M417 (like I0104 and most males from the Corded Ware culture) -, few generations later, show a decreased Yamna component, which clearly indicates that this individual’s admixture came directly from the steppe, and most likely from one or multiple female ancestors. That is compatible with the nomadic nature of the Corded Ware culture (and its known exogamy practices), which connected central Europe with the steppes, up to the North Caspian region.

If labelling other samples as outliers may be interesting to improve the conclusions one can obtain from genetic research, labelling this sample is, in my opinion, essential, to avoid certain strong misconceptions about the origin of the Corded Ware culture.

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