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Tuesday, July 20, 2021

On the origin of the Corded Ware people


There's been a lot of talk lately about the finding that the peoples associated with the Corded Ware and Yamnaya archeological cultures were close cousins (for instance, see here). As I've already pointed out, this is an interesting discovery, but, at this stage, it's difficult to know what it means exactly.

It might mean that the Yamnayans were the direct predecessors of the Corded Ware people. Or it might just mean that, at some point, the Corded Ware and Yamnaya populations swapped women regularly (that is, they practiced female exogamy with each other).

In any case, I feel that several important facts aren't being taken into account by most of the interested parties. These facts include, in no particular order:

- despite being closely related, the Corded Ware and Yamnaya peoples were highly adapted to very different ecological zones - temperate forests and arid steppes, respectively - and this is surely not something that happened within a few years and probably not even within a couple of generations

- both the Corded Ware and Yamnaya populations expanded widely and rapidly at around the same time, but never got in each others way, probably because they occupied very different ecological niches

- despite sharing the R1b Y-chromosome haplogroup, their paternal origins were quite different, with Corded Ware males rich in R1a-M417 and R1b-L51 and Yamnaya males rich in R1b-Z2103 and I2a-L699

I suppose it's possible that the Corded Ware people were overwhelmingly and directly derived from the Yamnaya population. But right now my view is that, even if they were, then the Yamnaya population that they came from was quite different from the classic, R1b-Z2103-rich Yamnaya that spread rapidly across the steppes.

Indeed, perhaps what we're dealing with here is a very early (proto?) Yamnaya gene pool located somewhere in the border zone between the forests and the steppes, that then split into two main sub-populations, with one of these groups heading north and the other south?

I do wonder what David Anthony would say if he was made aware of the above mentioned facts? Then again, perhaps he's already aware of them, and simply chose to ignore them when formulating his latest theory about the origin of the Corded Ware people?

See also...


Monday, June 28, 2021

The PIE homeland controversy: June 2021 status report


Archeologist David Anthony has made several appearances online recently to promote his theories about the origins of the Corded Ware and Yamnaya cultures and peoples.

In a clip on Youtube he reiterated his theory that the so called Iranian-related ancestry in the Yamnaya people actually came from what is now Iran, and, more precisely, that it was carried by hunter-gatherers who travelled relatively rapidly from the South Caspian region into the Volga Delta in what is now Russia.

It's still a complete mystery to me as to why a group of hunter-gatherers from the South Caspian would undertake such a migration, instead of, say, expanding their range gradually over thousands of years, first into the Caucasus and eventually into Eastern Europe.

But there's a more serious problem with Anthony's theory: it contradicts the currently available ancient DNA. That's because the so called Iranian-related ancestry in the Yamnaya people is most closely related to the Kotias and Satsurblia hunter-gatherers from what is now Georgia, and these hunter-gatherers form a separate clade from the earliest samples from what is now Iran. For instance, see here and here.

Also, in a podcast on Razib's blog, Anthony doubled down on his theory that Y-chromosome haplogroup R1a was closely associated with Yamnaya plebs who were excluded from Kurgan burials, and, as a result, their remains haven't yet been sampled.

At least this theory isn't yet contradicted by ancient DNA, but it's more complicated and less parsimonious than my theory, which posits that R1a, or rather R1a-M417, was simply a very rare lineage in the Yamnaya population, and that it only became a common and widespread marker thanks to the Corded Ware expansion (see here).

Intriguingly, my understanding is that there are several unpublished R1a samples from the Caspian and Volga steppes at Harvard's David Reich Lab that have been classified by its scientists as Yamnaya outliers. Of course, Anthony is collaborating on at least one major paper with this lab (see here).

Ergo, I strongly suspect that Anthony's theory is in part based on these Yamnaya outliers. However, I also believe that these samples are wrongly dated and probably represent Scythians and/or Sarmatians. I'll be able to look into that if they're ever published.

Speaking of the David Reich Lab, its leading scientists, David Reich and Nick Patterson, have also made appearances online recently, on Youtube and Razib's blog, respectively, to reveal that the Corded Ware and Yamnaya peoples aren't just very similar genetically, but in fact close cousins.

This is a very interesting finding. Apparently it's based on a relatively high level of Identity-by-Descent (IBD) segment sharing between Corded Ware and Yamnaya samples, but that's all I know. I'm guessing that the relevant paper is coming soon (that is, within the next five years).

However, the long-standing question that the readers of this blog want to see answered is not whether the Corded Ware and Yamnaya peoples are close cousins, but whether Yamnaya migrants founded the Corded Ware culture. The obvious way to prove that they did is to find at least one ancient population unambiguously classified as part of the Yamnaya horizon that is rich in the typically Corded Ware Y-haplogroups R1a-M417 and R1b-L151.

See also...

On the origin of the Corded Ware people

The PIE homeland controversy: January 2019 status report

The PIE homeland controversy: August 2019 status report

Thursday, June 17, 2021

Balto-Slavic drift


A few years ago I began using the term "Balto-Slavic genetic drift" to describe the fine-scale genetic signal that is shared by the speakers of Baltic and Slavic languages to the exclusion of Europeans without significant Balto-Slavic ancestry.

As a result, nowadays, many people online use the term "Balto-Slavic drift" when referring to this phenomenon.

The easiest way to prove that Balto-Slavic drift exists is to run a fine-scale Principal Component Analysis (PCA) of European genetic variation with a lot of Balto-Slavic samples in the mix. Indeed, my Global25 PCA analysis does a great job of illustrating the impact of Balto-Slavic drift on the population structure of Europe both in PCA plots and mixture models (for instance, see here).

It's also possible to tease out Balto-Slavic drift with formal statistics. I showed this indirectly in a recent blog post about Greek population structure (see here). In this post I'm going to demonstrate how to explicitly and formally test for Balto-Slavic drift both in ancient and present-day samples.

To do this we need to find stats that basically split Baltic and Slavic speakers from other Europeans, such as f4(Outgroup,Test;Bell_Beaker_NDL,Baltic_LVA_BA). In this f4-stat, Baltic_LVA_BA is the ancient reference population with an unusually high level of Balto-Slavic drift, while Bell_Beaker_NDL is a fairly similar population overall in terms of ancient ancestry components, but with practically zero Balto-Slavic drift.

Note that the statistics with the most significant Z scores (>3) involve populations that speak Baltic or Slavic languages, or their neighbors who plausibly harbor significant Baltic and/or Slavic ancestry. Among the ancient, mostly Scandinavian, populations (from Margaryan et al. 2020 and marked with the VK2020 prefix), significant Balto-Slavic drift only appears in the more easterly and/or later groups from the Viking Age (VA).


Unfortunately, one of the problems with this analysis is that Baltic_LVA_BA and Bell_Beaker_NDL aren't identical in terms of their ancient ancestry proportions. For one, the latter has significantly more Neolithic farmer ancestry. No wonder then, that Greeks, who are mostly of early farmer stock, don't show a significant Z score, despite probably packing a significant amount of Balto-Slavic ancestry dating to the Middle Ages.

In the near future, as more ancient samples become available, it might be possible to find better reference populations for the job and create more accurate, finer-scaled tests.

See also...

Uralian genes

That old chestnut: Northeast vs Northwest Euros

Tuesday, June 1, 2021

Eagle country


I took this photo of an eagle yesterday while hiking up a steep, rocky mountain, and wanted to share it with everyone here. This bird was one of six massive eagles that were thermal surfing in the valleys below.
Right after I took the picture I stepped on a small but unusually sharp rock that was sticking out of the ground. Incredibly, it cut through the sole of my shoe like the proverbial hot knife through butter, but only grazed my foot.

Nevertheless, I was in a lot of pain and decided to call it a day. I made my way down the mountain initially by hopping on one leg, and then, after collapsing twice from exhaustion, by crawling on all fours.

Overall, despite almost losing a foot, it was an awesome experience and I'm planning to go back into the mountains soon.

See also...

Looking forward to a post-Covid world

Friday, May 14, 2021

A Greek tragedy


I wasn't going to blog about the Clemente et al. "Aegean palatial civilizations" paper, because I think that it's a rather strange effort overall. But apparently a lot of people want to know my thoughts on the topic, so here goes.

If you download the relevant PDF file (here) and do a search for "Slav", you'll see that the word doesn't even appear in the bibliography. How is that possible, considering the massive impact that the Slavs had on the Balkans, including Greece, during the Middle Ages?

Indeed, here's a quote from page 12 of the PDF: "Present-day Greeks - who also carry Steppe-related ancestry - share ~90% of their ancestry with MBA northern Aegeans, suggesting continuity between the two time periods."

That's a very optimistic view. In fact, there's no evidence whatsoever in the paper that there's even 1% genetic continuity between present-day Greeks and any ancient Greek population, let alone the MBA northern Aegeans.

The genetic impact of Medieval Slavic migrations on most present-day Greek populations is easy to see. For instance, below are several linear models based on D-statistics of the form D(Outgroup,Test;Ancient1,Ancient2). You don't need a PhD in mathematics to understand them. The relevant data file is available here.

Note that most of the present-day Greek groups cluster together, and they also form fairly neat clines with the other Greeks, as well as Cypriots, other Balkan populations, including those speaking Slavic languages, and also the Slavic-speaking Ukrainians. On the other hand, they don't overlap with any of the ancient groups from Greece and surrounds, nor do they generally form obvious clines with them.

To me this suggests that most present-day Greeks harbor significant levels of Slavic ancestry and some sort of recent Cypriot-related ancestry, and in large part they're only coincidentally similar to ancient Aegeans, including those from the MBA (labeled Greece_Helladic_MBA in my graphs).

And let me assure you that no matter which ancient populations you run in such D-stats, you'll always see similar present-day Greek clusters and present-day Balkan clines.

Obviously, it's fair enough to assume that there's been some genetic continuity in the Aegean from the Iron Age, Bronze Age, and even the Copper Age and Neolithic era to the present-day. But the point I'm making is that no one has yet proved this, or even attempted to measure it properly.

See also...

Greek confirmation bias

Monday, April 26, 2021

Uralians of the Sargat horizon


Many years ago, well before the start of the ancient DNA revolution, someone made the very clever inference that the N-Tat Y-chromosome marker was closely associated with the expansion of Uralic languages.

Since then, N-Tat has been renamed several times over, to the point that I no longer know what it's called, but the aforementioned inference has turned into a very solid consensus backed up by a wide range of studies focusing on modern and ancient DNA.

Nowadays, Y-haplogroup N-L1026, a subclade of N-Tat, is seen as the main genetic signal of the Uralic expansions, along, of course, with Nganasan-related genome-wide genetic ancestry.

A recent paper at Science Advances by Gnecchi-Ruscone et al. featured the first ever genome-wide samples from the Sargat horizon, which is an Iron Age archeological formation in western Siberia normally associated with the Ugric branch of the Uralic language family. Surprisingly, and disappointingly, the authors failed to investigate this widely accepted connection.

If we go by the Y-haplogroup classifications in the paper, which may or may not be the smart thing to do, at least two of the Sargat horizon males belong to N-L1026, and one also to the more derived N-Z1936 subclade, which has been found in the remains of Hungarian Conquerers from Medieval Hungary. Of course, Hungarian is an Ugric language generally thought to have been introduced into the Carpathian Basin by the Hungarian Conquerers who originally came from western Siberia.

That's probably enough to corroborate the association between the Sargat horizon and the spread of Ugric/Uralic languages, but let's also take a quick look at the autosomal DNA of these Sargat individuals. Firstly, here's a Principal Component Analysis (PCA), based on Global25 data and produced with the Vahaduo G25 Views online tool. The results are self-explanatory.


Interestingly, I can't get a decent statistical fit when I try to reproduce the four-way qpWave/qpAdm model done by Gnecchi-Ruscone et al., probably mostly because my right pops or outgroups are different. This suggests to me that there's something important missing in their model.

Sargat_IA
MNG_Khovsgol_LBA 0.203±0.045
RUS_Ekven_IA 0.183±0.044
RUS_Sintashta_MLBA 0.545±0.014
TKM_Gonur1_BA 0.068±0.013
chisq 16.805
tail prob 0.0186971
Full output

So how about if I replace RUS_Ekven_IA with kra001, the oldest Nganasan-like individual in the ancient DNA record (see here), and MNG_Khovsgol_LBA with KAZ_Mereke_MBA, to add a more local stream of ancestry?

Sargat_IA
KAZ_Mereke_MBA 0.135±0.017
kra001 0.301±0.007
RUS_Sintashta_MLBA 0.499±0.023
TKM_Gonur1_BA 0.066±0.015
chisq 8.872
tail prob 0.262001
Full output

That's a better statistical fit and also, I'd say, a more realistic model, at least in terms of distal ancestry proportions. Note that Nganasan-related ancestry makes up 30% of the genome-wide genetic structure of the Sargat samples, which again corroborates the view that Uralic languages were spoken within the Sargat horizon.

Update 28/04/21: This is the best qpAdm model that I could find for Sargat_IA, at least in terms of the chisq and tail prob. It shows that the Sargat population was in large part very similar to that of KAZ_Pazyryk_IA.

Sargat_IA
KAZ_Mereke_MBA 0.032±0.016
KAZ_Pazyryk_IA 0.698±0.016
RUS_Sintashta_MLBA 0.236±0.021
TKM_Gonur1_BA 0.034±0.014

chisq 2.023
tail prob 0.958561
Full output

It's missing kra001, because KAZ_Pazyryk_IA packs enough kra001-related ancestry for the job.

KAZ_Pazyryk_IA
KAZ_Mereke_MBA 0.144±0.018
kra001 0.429±0.008
RUS_Sintashta_MLBA 0.378±0.026
TKM_Gonur1_BA 0.049±0.018

chisq 8.899
tail prob 0.259983
Full output

The fact that KAZ_Pazyryk_IA can be modeled with significant kra001-related ancestry isn't surprising, considering that its territory was located in Siberia. However, my model doesn't necessarily prove that the Sargat population was largely or even partly of Pazyryk origin. Indeed, N-L1026 hasn't yet appeared in any Pazyryk remains.

See also...

The Uralic cline with kra001 - no projection this time

First taste of Early Medieval DNA from the Ural region

Hungarian Conquerors were rich in Y-haplogroup N

More on the association between Uralic expansions and Y-haplogroup N

It was always going to be this way

On the association between Uralic expansions and Y-haplogroup N

Thursday, April 22, 2021

The history of the Scythians (Gnecchi-Ruscone et al. 2021)


Over at Science Advances at this LINK. Many of the samples from this paper are in the Global25 datasheets. Look for the relevant population and individual IDs from the paper.

The Scythians were a multitude of horse-warrior nomad cultures dwelling in the Eurasian steppe during the first millennium BCE. Because of the lack of first-hand written records, little is known about the origins and relations among the different cultures. To address these questions, we produced genome-wide data for 111 ancient individuals retrieved from 39 archaeological sites from the first millennia BCE and CE across the Central Asian Steppe. We uncovered major admixture events in the Late Bronze Age forming the genetic substratum for two main Iron Age gene-pools emerging around the Altai and the Urals respectively. Their demise was mirrored by new genetic turnovers, linked to the spread of the eastern nomad empires in the first centuries CE. Compared to the high genetic heterogeneity of the past, the homogenization of the present-day Kazakhs gene pool is notable, likely a result of 400 years of strict exogamous social rules.

Gnecchi-Ruscone et al. 2021, Ancient genomic time transect from the Central Asian Steppe unravels the history of the Scythians, Science Advances, Sci Adv 7 (13), eabe4414, DOI: 10.1126/sciadv.abe4414

See also...

Uralians of the Sargat horizon

Wednesday, April 7, 2021

The Bacho Kiro surprise (Hajdinjak et al. 2021)


Over at Nature at this LINK. The paper focuses on Neanderthal ancestry in Initial Upper Paleolithic (IUP) humans from what is now Bulgaria. But, to me, much more interesting is the claim by its authors that present-day East Asians harbor ancient European, or, at least, European-related ancestry. From the paper, emphasis is mine:

When we explored models of population history that are compatible with the observations above using admixture graphs [28], we found that the IUP Bacho Kiro Cave individuals were related to populations that contributed ancestry to the Tianyuan individual in China as well as, to a lesser extent, to the GoyetQ116-1 and Ust’Ishim individuals (all |Z| < 3; Fig. 2d, Supplementary Information 6). This resolves the previously unclear relationship between the GoyetQ116-1 and Tianyuan individuals [13] without the need for gene flow between these two geographically distant individuals.

...

In conclusion, the Bacho Kiro Cave genomes show that several distinct modern human populations existed during the early Upper Palaeolithic in Eurasia. Some of these populations, represented by the Oase1 and Ust’Ishim individuals, show no detectable affinities to later populations, whereas groups related to the IUP Bacho Kiro Cave individuals contributed to later populations with Asian ancestry as well as some western Eurasian humans such as the GoyetQ116-1 individual in Belgium. This is consistent with the fact that IUP archaeological assemblages are found from central and eastern Europe to present-day Mongolia [5,15,16] (Fig. 1), and a putative IUP dispersal that reached from eastern Europe to East Asia. Eventually populations related to the IUP Bacho Kiro Cave individuals disappeared in western Eurasia without leaving a detectable genetic contribution to later populations, as indicated by the fact that later individuals, including BK1653 at Bacho Kiro Cave, were closer to present-day European populations than to present-day Asian populations [29,30].

Hajdinjak, M., Mafessoni, F., Skov, L. et al. Initial Upper Palaeolithic humans in Europe had recent Neanderthal ancestry. Nature 592, 253–257 (2021). https://doi.org/10.1038/s41586-021-03335-3

See also...

Ust'-Ishim belongs to K-M526

Wednesday, March 31, 2021

Against the conventional wisdom


I've read some very strange theories over the years trying to explain who was responsible for the so called Caucasus/Iranian-related ancestry in the Yamnaya people.

Proto-Indo-European speaking farmers from what is now Iran? How about Uruk invaders from Mesopotamia? No, wait, they were migrants from India who spoke Sanskrit. Haha.

Nope, it seems that hunter-gatherers rich in this type of ancestry lived north of the Caucasus already during the so called Pottery Neolithic or even the Mesolithic. That's the impression that I'm getting from watching the clip HERE.

This is basically also the idea that I gradually developed at this blog during the last few years, following common sense and logic, but totally against the conventional wisdom in regards to this topic. For instance, see here...

But here's my prediction: Steppe_EMBA only has 10-15% admixture from the post-Mesolithic Near East not including the North Caucasus, and basically all of this comes via female mediated gene flow from farming communities in the Caucasus and perhaps present-day Ukraine.
Modeling Steppe_EMBA

Of course, I could've done better with many of the details in my posts, like the dates and archeological links. But hey, at least I was smart enough to ignore the conventional wisdom.

I can't wait for the new ancient samples from the Pontic-Caspian steppe that David Anthony featured in his talks recently. Once I have them we'll be able to work out the details here for ourselves.

See also...

Ahead of the pack

Ancient DNA vs Ex Oriente Lux

Understanding the Eneolithic steppe

Sunday, March 14, 2021

How the Shirenzigou nomads became Proto-Tocharians


A couple of years ago, the authors of a paper about a group of Iron Age nomads from the site of Shirenzigou, in the eastern Tian Shan, made a mistake. They wrongly assigned two of these nomads to Y-haplogroup R1b-M269.

This faux pas made them believe that the Shirenzigou nomads were closely related to the M269-rich population associated with the Afanasievo culture.

Indeed, since the Afanasievo culture was often credited with the spread of Tocharian languages to the Tarim Basin, these authors, led by Chao Ning, also concluded that the Shirenzigou nomads were potentially the missing link between the Afanasievo culture and the Tocharians (see here).

Moreover, Ning et al. used formal statistics to argue that the Shirenzegou nomads harbored Afanasievo-related genome-wide ancestry, rather than Sintashta-related genome-wide ancestry, despite the fact that the latter ancestry was widespread in the Tian Shan and surrounds during the Bronze and Iron ages. Soon after, another group of authors, led by Chuan-Chao Wang, also went out of their way to link the Shirenzigou nomads to the Afanasievo people with genome-wide DNA using formal statistics (see here).

Interestingly, one of the Shirenzigou nomads belongs to Y-haplogroup R1a-Z93, which is an obvious Sintashta-related lineage. Both Ning et al. and Wang et al. missed this important fact.

They also missed the key fact that the R1b lineage found in the Shirenzigou nomads actually belongs a native Central Asian subclade, which is only very distantly related to the originally Eastern European R1b-M269.

Now, formal stats are a very useful tool for studying genome-wide ancestry. But they're not infallible, and that's actually something of an understatement. Indeed, if you don't run sanity checks when using formal stats, you're likely to come to some unusual, even arse about face, conclusions. Uniparental markers, like Y-chromosome haplogroups, can provide a robust sanity check when running formal stats on genome-wide data.

One problem with formal stats is that Sintashta-related ancestry often looks very much like Afanasievo-related ancestry when it's mixed with indigenous Central Asian ancestry. Basically, the reason why this happens is that the Central Asian ancestry dampens the Early European Farmer (EEF) signal in the Sintashta-related ancestry.

This is an artifact that once caused scientists at Harvard to believe that Central Asian Scythians and present-day South Asians lacked Sintashta-related ancestry.

Unfortunately, since the publication of the Ning et al. paper, a consensus has emerged in academia that the Shirenzigou nomads are indeed the missing link between the Afanasievo culture and the Tocharians. But, let's be objective and honest here, it's a consensus based on nothing more than a comedy of errors.

On the other hand, me and most of the commentators at this blog have formed opinions about the Shirenzigou nomads that are totally at odds with the academic consensus, that:

- they're a complex mixture of Sintashta-related, indigenous Central Asian and Tibetan-related ancestries, with no clear, unambiguous signal of Afanasievo-related ancestry

- they weren't the speakers of Proto-Tocharian or even related in any specific way to the Tocharians

- they were probably the speakers of a now extinct Indo-Iranian language, and, at least based on geographic proximity, possibly related to the Yuezhi.

Feel free to make up your own mind. But for me, the question of how Tocharian languages ended up in the Tarim Basin remains wide open. I admit though, I'm currently quite partial to the idea floated here by commentator Copper Axe that the Chemurchek culture may have had something to do with it.

See also...

Don't believe everything you read in peer reviewed papers