The PIE homeland controversy: December 2024 open thread

It seems like we're getting close to the moment when Iosif Lazaridis has to finally admit that the Proto-Indo-European (PIE) homeland was located in Eastern Europe, and also that the ancestors of the Hittites and other Anatolian speakers entered Anatolia via the Balkans.

Let's discuss.

However, please note that comments from total morons, trolls and/or mentally unstable people will not be approved.

See also...

Indo-European crackpottery

Romans and Slavs in the Balkans (Olalde et al. 2023)

It's always amusing to see some random Jovan or Dimitar arguing online that Slavic speakers have been in the Balkans since at least the Neolithic.

Obviously, Slavic peoples only turned up in the Balkans during the early Middle Ages. It's just that their linguistic and genetic impact on the region was so profound that it may seem like they've been there forever.

A new paper at Cell by Olalde et al. makes this point well. See here.

That's not to say, however, that it's an ideal effort. The paper's qpAdm mixture models probably could've been more precise and realistic. Genes of the Ancients has a useful discussion on the topic here.

Interestingly, Olalde et al. admit that they can't detect much, if any, admixture from the Italian Peninsula in the Balkans, even in samples dating to the Roman period. And yet, this doesn't stop them from accepting that the Roman Empire had a massive cultural and demographic impact on the Balkans.

I also assume that, by extension, they don't deny that Latin was introduced into the Balkans from the Italian Peninsula.

That is, Latin spread into the Balkans without any noticeable genetic tracer dye, and it eventually gave rise to modern Romanian spoken by millions of people today in the eastern Balkans. This might be a useful data point to keep in mind when discussing the spread of Indo-European languages into Anatolia.

See also...

Dear Iosif, about that ~2%

The Yassitepe challenge

This is about the only successful qpAdm model that I can find for the pair of Early Bronze Age (EBA) females from Yassitepe, Turkey, using a decent set of outgroups and markers. I wouldn't take it too literally, but it does suggest a potentially significant level of European ancestry, including some steppe ancestry, in these Yassitepe individuals.

TUR_Aegean_Yassitepe_EBA
AZE_Caucasus_lowlands_LN 0.565±0.054
ROU_N 0.387±0.041
RUS_Progress_En 0.048±0.022
P-value 0.103248
Full output

If anyone reading this can find a better, more convincing solution then I'd love to see it. Feel free to share it in the comments below.

Obviously, both of the Yassitepe samples are from the recent Lazaridis, Alpaslan-Roodenberg et al. paper. Their EBA dating suggests that they might be relevant to the debate over the origins of Anatolian speakers, such as the Hittites and Luwians.

See also...

Dear Iosif, about that ~2%

The precursor of the Trojans

Dear Iosif, about that ~2%

The debate over the location of the so called Indo-Anatolian homeland won't be decided by the persistence of any type of genetic ancestry in ancient Anatolia.

It'll be decided by a multidisciplinary study on the interactions between the ancient peoples of the North Pontic steppe, the eastern Balkans, and western Anatolia.

If such a study finds a pulse of steppe-related gene flow from the Balkans into Anatolia sometime during the early metal ages, it'll corroborate the linguistic hypothesis that a language ancestral to Hittite, Luwian and related tongues moved into Anatolia from Eastern Europe.

Why do we only need a pulse of gene flow, you might ask? Obviously, because:

- language and genetic ancestry can start with a strong association but, since they're not linked, they can eventually follow very different trajectories

- the dilution of genetic ancestry is an important factor, especially in ancient West Asia, and it must be taken into account in models of language spread, rather than ignored in favor of simple, elegant models that do not reflect reality.

Here's my favorite quote from the recent Lazaridis, Alpaslan-Roodenberg et al. paper, because, probably unbeknownst to the authors, it's exceptionally revealing about the spread of a wide range of Indo-European speakers into Anatolia.

However, in individuals from Gordion, a Central Anatolian city that was under the control of Hittites before becoming the Phrygian capital and then coming under the control of Persian and Hellenistic rulers, the proportion of Eastern hunter-gatherer ancestry is only ~2%, a tiny fraction for a region controlled by at least four different Indo-European–speaking groups.

Indeed, this is exactly what the Lazaridis, Alpaslan-Roodenberg et al. paper should've been about. That is, the authors should've given us a painstaking account of the spread of different ancient Indo-European speaking groups into Anatolia and explained how, overall, their DNA was rapidly diluted to a trace amount.

However, instead they treated us to a make-believe tale about a so called Indo-Anatolian homeland in what is now Armenia.

See also...

Dear Iosif...Yamnaya

But Iosif, what about the Phrygians?

Dear Iosif...

Dear Iosif #2

Dear Iosif #3

But Iosif, what about the Phrygians?

A paper in Science co-authored by around 200 scientists from some of the world's top academic institutions surely must mean something, right? Not necessarily.

In this short blog post I'll try to explain, as simply as I can, why the Lazaridis, Alpaslan-Roodenberg et al. paper doesn't get us any closer to solving the riddle of the so called Indo-Anatolian homeland.

However, it must be said that the paper does include many interesting and valuable samples. I'll be using six of these samples, labeled TUR_C_Gordion_Anc, to argue my case.

The TUR_C_Gordion_Anc sample set is from Gordion, the capital of ancient Phrygia, and thus, in all likeliness, it represents Phrygian speakers.

Phrygian is an Indo-European language and the leading hypothesis is that it originated in the Balkans.

In terms of fine scale ancestry, TUR_C_Gordion_Anc can be reliably divided into two genetic clusters. In the Principal Component Analysis (PCA) below these clusters are labeled TUR_C_Gordion_Anc1 and TUR_C_Gordion_Anc2.

Note that TUR_C_Gordion_Anc1 is obviously pulling away from TUR_C_Gordion_Anc2 towards samples from the Balkans. I've used ancient samples from what is now North Macedonia, labeled MKD_Anc, to represent the Balkans. To see an interactive version of the plot, paste the PCA coordinates from here into the relevant field here.

Visually, this is not an especially dramatic outcome, but it's an incredible result nonetheless, because it shows that even a few ancient samples can help to solve an age old mystery.

Across many dimensions of genetic variation, the shift in the PCA from TUR_C_Gordion_Anc1 to TUR_C_Gordion_Anc2 represents about 20% admixture from the Balkans, and about 8% from the Eastern European steppe. That's plenty enough to corroborate the linguistic hypothesis that the Phrygians originated in the Balkans, and that some of their ancestors came from the steppe. The mixture models below were done with the tools here.

Target: TUR_C_Gordion_Anc1
Distance: 1.6634% / 0.01663373
40.6 Kura-Araxes_ARM_Kaps
22.2 Anatolia_Barcin_N
21.8 MKD_Anc
13.6 Levant_PPNB
1.4 IRN_Ganj_Dareh_N
0.4 Han

Target: TUR_C_Gordion_Anc1
Distance: 1.7109% / 0.01710904
40.2 Kura-Araxes_ARM_Kaps
37.8 Anatolia_Barcin_N
12.4 Levant_PPNB
8.0 Yamnaya_RUS_Samara
1.2 IRN_Ganj_Dareh_N
0.4 Han

Target: TUR_C_Gordion_Anc2
Distance: 2.0293% / 0.02029339
51.0 Kura-Araxes_ARM_Kaps
26.8 Anatolia_Tepecik_Ciftlik_N
17.6 Anatolia_Barcin_N
4.6 Levant_PPNB

Surprisingly, Lazaridis, Alpaslan-Roodenberg et al. didn't have much to say about this topic. This quote basically sums it up:

However, in individuals from Gordion, a Central Anatolian city that was under the control of Hittites before becoming the Phrygian capital and then coming under the control of Persian and Hellenistic rulers, the proportion of Eastern hunter-gatherer ancestry is only ~2%, a tiny fraction for a region controlled by at least four different Indo-European–speaking groups.

I have no doubt that Lazaridis, Alpaslan-Roodenberg et al. can run a very decent PCA, and then blow it up to a size big enough to show that the Gordion samples represent two genetically somewhat distinct groups. I'm also sure that, if they really try, they can locate significant levels of proximate and relevant European ancestry in some of these samples.

They don't have to use my methods; they can use any methods they like. My point is that they won't find much if they're just looking for genetic signals from the Upper Paleolithic or Mesolithic.

Now, considering the way that the Phrygian question was treated by Lazaridis, Alpaslan-Roodenberg et al., despite the fact that they managed to sequence a few likely Phrygian speakers from none other than the Phrygian capital, let's not pretend that their paper brought us any closer to understanding the genetic origins of Anatolian speakers or pinpointing their ancestral homeland.

In order to even try to solve these problems with ancient DNA, we need a wide range of samples from Hittite, Luwian and other key sites where Anatolian languages were spoken. And then we must analyze them properly.

I'm guessing that Lazaridis, Alpaslan-Roodenberg et al. went out of their way to get such samples, but for one reason or another they failed. If so, that's OK, but I have a feeling that even if they got them, they wouldn't know what to do with them, because at best these samples would only show ~2% Eastern hunter-gatherer ancestry. Haha.

For what it's worth, I believe that the ancient data in the Lazaridis, Alpaslan-Roodenberg et al. paper point to the North Pontic steppe as the Indo-Anatolian homeland, and I'll lay out my arguments in an upcoming blog post.

See also...

Dear Iosif...Yamnaya

Dear Iosif, about that ~2%

Dear Iosif...

Dear Iosif #2

Dear Iosif #3

The genomic formation of modern Balkan peoples (Olalde et al. 2021 preprint)

Over at bioRxiv at this LINK. This preprint deals with some very complex issues, so I can't say much about it until I have a good look at the relevant genotype data. However, for now, my impression is that the authors have oversimplified the genetic origins of most Balkan peoples.

For instance, they model the present-day Greek population as a two way mixture between ancient Greeks from a Greek colony in Iberia and present-day Mordovians. The Mordovians are basically a proxy for the Slavs who moved into the Balkans during the Medieval period.

However, the problem is that, strictly speaking, this isn't a historically plausible model, because Mordovians are actually a Uralic-speaking group from the Volga region with significant Siberian ancestry. Needless to say, it's extremely unlikely that anyone like them had an appreciable impact on the present-day Greek gene pool.

So instead I'd like to see the authors try three-way and four-way models with ancients from Mycenae, Anatolia and some places (well to the west of the Volga River) likely to have been inhabited by early Slavs.

Feel free to let me know what you think about this preprint in the comments below. Here's the abstract:

The Roman Empire expanded through the Mediterranean shores and brought human mobility and cosmopolitanism across this inland sea to an unprecedented scale. However, if this was also common at the Empire frontiers remains undetermined. The Balkans and Danube River were of strategic importance for the Romans acting as an East-West connection and as a defense line against “barbarian” tribes. We generated genome-wide data from 70 ancient individuals from present-day Serbia dated to the first millennium CE; including Viminacium, capital of Moesia Superior province. Our analyses reveal large scale-movements from Anatolia during Imperial rule, similar to the pattern observed in Rome, and cases of individual mobility from as far as East Africa. Between ∼250-500 CE, we detect gene-flow from Central/Northern Europe harboring admixtures of Iron Age steppe groups. Tenth-century CE individuals harbored North-Eastern European-related ancestry likely associated to Slavic-speakers, which contributed >20% of the ancestry of today’s Balkan people.

Olalde et al., Cosmopolitanism at the Roman Danubian Frontier, Slavic Migrations, and the Genomic Formation of Modern Balkan Peoples, bioRxiv, posted August 31, 2021, doi: https://doi.org/10.1101/2021.08.30.458211

See also...

A Greek tragedy

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

The precursor of the Trojans

Who remembers kum4 from Omrak et al. 2016? I'm pretty sure now that this individual packs a lot of ancestry from the Pontic-Caspian (PC) steppe.

If so, that's a big deal, because her Chalcolithic (or Late Neolithic?) burial was located at Kumtepe. That is, in the same part of Anatolia as the later settlement of Troy, which may have been founded by early Anatolian speakers from Eastern Europe (see here).

The qpAdm mixture models below, featuring kum4 and the likely older kum6, also from Kumtepe, are based on qpfstats output. qpfstats is a new program from the David Reich Lab specifically designed to help analyze low coverage ancients (see here). And kum4 is certainly that.

TUR_Kumtepe_N_kum4
RUS_Progress_En 0.383±0.114
TUR_Barcin_N 0.617±0.114
chisq 7.868
tail prob 0.247957
Full output

TUR_Kumtepe_N_kum4
IRN_Seh_Gabi_C 0.325±0.150
TUR_Barcin_N 0.675±0.150
chisq 14.736
tail prob 0.0224096
Full output

TUR_Kumtepe_N_kum6
RUS_Progress_En 0.121±0.042
TUR_Barcin_N 0.879±0.042
chisq 21.790
tail prob 0.00132149
Full output

TUR_Kumtepe_N_kum6
IRN_Seh_Gabi_C 0.283±0.059
TUR_Barcin_N 0.717±0.059
chisq 6.289
tail prob 0.391566
Full output

Indeed, kum4 and kum6 offer just ~10,000 and ~100,000 "valid SNPs", respectively (see here). However, if nothing else, the results are clearly not random.

For one, because they fit the expected pattern, with the likely older individual lacking ancestry from the PC steppe (her model with RUS_Progress_En shows a weak statistical fit). Moreover, the qpAdm mixture ratios align almost perfectly with the results in my Principal Component Analysis (PCA) of ancient West Eurasian genetic variation. Coincidence?

See also...

Perhaps a hint of things to come

Perhaps a hint of things to come

It's still a mystery how the Hittites and other Anatolian speakers ended up in the Near East. However, the leading theory is that their ancestors migrated from the steppes of Eastern Europe to western Anatolia via the Balkans sometime during the Copper Age.

Consider the qpAdm mixture models below, made possible thanks to some of the ancient samples published recently along with Skourtanioti et al. 2020. The key ancients are described in a text file available here.

TUR_Barcin_C
AZE_Caucasus_lowlands_LN 0.471±0.094
RUS_Vonyuchka_En 0.148±0.040
TUR_Barcin_N 0.381±0.069
chisq 12.874
tail prob 0.116261
Full output

TUR_Barcin_C
RUS_Vonyuchka_En 0.107±0.029
TUR_Buyukkaya_EC 0.893±0.029
chisq 12.107
tail prob 0.207331
Full output

I'd say it's quite clear now that TUR_Barcin_C harbors minor ancestry from the Pontic-Caspian (PC) steppe. The reason this isn't widely accepted yet is because demonstrating it convincingly hasn't been possible without a proximate Anatolian ancestry source for TUR_Barcin_C, precisely like TUR_Buyukkaya_EC.

Admittedly, though, the statistical fits in my models aren't all that great. I suspect the problem lies with RUS_Vonyuchka_En, which is likely to be a rather poor stand in for the people who brought steppe ancestry, and possibly early Anatolian speech, to western Anatolia.

So let's see what happens when I try a more proximate reference for the steppe ancestry in TUR_Barcin_C. How about Yamnaya_BGR, an individual of mixed Balkan and steppe origin from what is now Bulgaria?

TUR_Barcin_C
AZE_Caucasus_lowlands_LN 0.518±0.075
TUR_Barcin_N 0.203±0.056
Yamnaya_BGR 0.279±0.067
chisq 10.602
tail prob 0.225269
Full output

TUR_Barcin_C
TUR_Buyukkaya_EC 0.749±0.058
Yamnaya_BGR 0.251±0.058
chisq 9.687
tail prob 0.376414
Full output

That's a little better. Unfortunately, the problem now is that the models are anachronistic, because TUR_Barcin_C is about a thousand years older than Yamnaya_BGR. Clearly, we need more Copper Age samples from the western edge of the PC steppe, the eastern Balkans, and especially northwestern Anatolia.

The Principal Component Analysis (PCA) below effectively illustrates why my qpAdm models work. It was produced with Global25 data using the Vahaduo PCA tools freely available here. Note that TUR_Barcin_C is shifted away from the essentially perfect cline formed by AZE_Caucasus_lowlands_LN, TUR_Barcin_N and TUR_Buyukkaya_EC towards samples from ancient Eastern Europe, including Yamnaya_BGR.

See also...

Steppe invaders in the Bronze Age Balkans

Early chariot riders of Transcaucasia came from...

I'm finding it increasingly difficult nowadays to fully appreciate all of the ancient DNA samples that are accumulating in my dataset. But it's not entirely my fault.

Among the hundreds of ancient samples published last year there was a couple of Middle Bronze Age (MBA) individuals from what is now Armenia labeled "Lchashen Metsamor" (see here). I wasn't planning to do much with these samples because, even after reading the Nature paper that they came with a couple times over, I didn't have a clue what they were about. But after some digging around, I now know that their people, those associated with the Lchashen Metsamor archeological culture, were among the earliest in Transcaucasia, and indeed the Near East, to use the revolutionary spoked-wheel horse chariot. How awesome is that?

The invention of the spoked-wheel chariot is generally credited to the Middle Bronze Age Sintashta culture of the Trans-Ural steppe in Central Asia, and its rapid spread is often associated with the early expansions of Indo-European languages deep into Asia. On the other hand, some have argued that this type of chariot was first developed in the Near East, and directly derived from solid-wheeled wagons pulled by donkeys.

It's now obvious, thanks to ancient DNA, that the Sintashta people were by and large migrants to Central Asia from somewhere in Eastern Europe, and that they didn't harbor any recent ancestry from the Near East. So if chariot technology spread into the steppes from the Near East, then it did so without any accompanying gene flow, which is possible but not entirely convincing. This begs the question of whether the Lchashen Metsamor population was of Sintashta-related origin, because if it was, then this would corroborate the consensus that spoked-wheel chariots were introduced into Transcaucasia from the steppes to the north.

Below is a Principal Component Analysis (PCA) of West Eurasian genetic variation. It does suggest that the Lchashen Metsamor pair (labeled Armenia_MBA_Lchashen), as well as most of the other currently available samples from what is now Armenia dating to the Middle to Late Bronze Age (MLBA), harbor some steppe ancestry. That's because they appear to form a cline between samples associated with the Sintashta and Kura-Araxes cultures. Of course, the Kura-Araxes culture was a major Early Bronze Age (EBA) archeological phenomenon centered on Transcaucasia and surrounds, so its population can be reasonably assumed to have formed the genetic base of most subsequent populations in the region. The relevant PCA datasheet is available here.

To investigate the possibility of Sintashta-related admixture in Lchashen Metsamor with formal methods, I ran a series of mixture models with the qpAdm software. Here are the three statistically most sound outcomes that I was able to come up with for Lchashen Metsamor:

Armenia_MBA_Lchashen
CWC_Kuyavia 0.183±0.036
Kura-Araxes_Kaps 0.817±0.036
chisq 13.941
tail prob 0.378021
Full output

Armenia_MBA_Lchashen
Balkans_BA_I2163 0.193±0.045
Kura-Araxes_Kaps 0.807±0.045
chisq 14.780
tail prob 0.321267
Full output

Armenia_MBA_Lchashen
Kura-Araxes_Kaps 0.788±0.043
Sintashta_MLBA 0.212±0.043
chisq 14.871
tail prob 0.315451
Full output

I sorted the output by "tail prob", but the fact that Sintashta_MLBA is in third place isn't a problem because the stats in all of these models are basically identical. Indeed, CWC_Kuyavia (Corded Ware culture samples from present-day Kuyavia, North-Central Poland) and Balkans_BA_I2163 (a Bronze Age singleton from what is now Bulgaria) are both very similar and probably closely related to each other and to the Sintashta samples.

Interestingly, and, I'd say, importantly, ancients from the steppe that are closest to Lchashen Metsamor in both space and time, but not particularly closely related to the Sintashta people, don't work too well as a mixture source in such models.

Armenia_MBA_Lchashen
Kubano-Tersk 0.184±0.046
Kura-Araxes_Kaps 0.816±0.046
chisq 22.179
tail prob 0.0526526
Full output

A couple of months ago I suggested that populations associated with the Early to Middle Bronze Age (EMBA) Catacomb culture were the vector for the spread of steppe ancestry into what is now Armenia during the MLBA (see here). After taking a closer look at the Lchashen Metsamor samples, I now think that the peoples of the Sintashta and related cultures were also important in this process. If so, they may have moved from the steppe into Transcaucasia both from the west via the Balkans and the east via Central Asia, and brought with them spoked-wheel chariots. I don't have a clue what language they spoke, but I'm guessing that it may have been something Indo-European.

See also...

The mystery of the Sintashta people

A potentially violent end to the Kura-Araxes Culture (Alizadeh et al. 2018)

Late PIE ground zero now obvious; location of PIE homeland still uncertain, but...

Late PIE ground zero now obvious; location of PIE homeland still uncertain, but...

All of the post-Middle Neolithic samples from the recent Mittnik et al. and Saag et al. preprints on the ancient population history of the Baltic region belonged to Y-chromosome haplogroup R1a. And most of them belonged to the R1a-M417 (R1a1a) subclade that makes up almost 100% of the R1a lineages in the world today. This is what the results look like in a table (the sample IDs are of my own design):

Earlier samples from the same region belonged to Y-haplogroups I2a and R1a, but this was a subclade of R1a defined by the YP1272 mutation that is extremely rare today even in Northeastern Europe.

And now shifting our focus west of Scandinavia: all but two of the post-Middle Neolithic samples from around the North Sea from the recent Olalde et al. preprint on the Bell Beaker phenomenon and ancient population history of Northwest Europe belonged to Y-chromosome R1b, and more specifically to the R1b-M269 (R1b1a1a2) subclade, which makes up almost 100% of the R1b lineages in the world today. Here's a table:

Earlier samples from the same region belonged to Y-haplogroups I2a, I, G2a and CF, and most of the instances of I and the CF would probably be classified as I2a if not for missing data.

Interestingly, despite the R1a vs R1b dichotomy between these post-Middle Neolithic obvious newcomers to the Baltic and North Sea regions, respectively, they were very similar in terms of overall genetic structure, obviously closely related, starkly different from Middle Neolithic Northern Europeans, and in all likelihood mainly derived from the same homeland that was not located in Northern Europe.

So can we locate this homeland with any degree of certainty, you might wonder? In fact, you might ask, isn't this a futile search for the time being, as we await ancient DNA from many prehistoric Eurasian populations?

Not at all, because when attempting to answer this question we're bounded by two key constraints: the exceptionally high frequencies of R1a and R1b in the post-Middle Neolithic Baltic and North Sea samples, and their close genetic affinity to earlier and contemporaneous populations from the Pontic-Caspian steppe, part of which is due to significant Caucasus Hunter-Gatherer (CHG) admixture that was lacking in Middle Neolithic Northern Europeans.

Indeed, to date, the Pontic-Caspian steppe is the only region where both R1a and R1b have been found in ancient remains from the same sites dating to the Mesolithic, Neolithic and Eneolithic. Here's a table based on results from Mathieson et al. 2015 and 2017. The R and R1 might really be R1a or R1b if not for missing data.

The Pontic-Caspian steppe also abuts the Caucasus foothills, and we know that CHG admixture was a major feature of its inhabitants from at least the Eneolithic. So odds are, and make no mistake, these are indeed excellent odds, that the homeland we're looking for was on the Pontic-Caspian steppe.

But of course I2a has also been recorded in prehistoric samples from the Pontic-Caspian steppe. So, you might ask, why did the populations migrating out of the steppe belong to R1a and R1b, and why did some of them seemingly carry only R1a while others only R1b? This can be explained by local founder effects on the steppe due to patrilocality. Moreover, it's possible that some groups moving out of the steppe did carry high frequencies of I2a, but they're yet to enter the ancient DNA record. [Edit: Maybe they already have? See here]

Now, the aforementioned post-Middle Neolithic newcomers to the Baltic and North Sea regions are most certainly in large part the direct ancestors of modern-day Northern Europeans, speaking languages belonging to the three daughter branches of late Proto-Indo-European (PIE): Balto-Slavic, Celtic and Germanic. It's highly unlikely that languages ancestral to these present-day languages were spoken by Middle Neolithic farmers, nor introduced into Northern Europe after it was colonized by the migrants from the Pontic-Caspian steppe.

What this strongly suggests is that the Pontic-Caspian steppe was also the late PIE homeland.

But, you might argue, the Pontic-Caspian steppe may have just been the expansion point for some of the late PIE language branches. No, that won't work. For one, modern-day populations speaking languages belonging to all other late PIE branches, such as Armenian, Greek, Indo-Iranian and Italic, show signals of the same population expansion from the Pontic-Caspian steppe that gave rise to modern-day Northern Europeans, in the form of Yamnaya-related genome-wide genetic admixture and appreciable frequencies of Y-chromosome haplogroups R1a-M417 and/or R1b-M269.

Some of these signals are certainly due to fairly recent admixture from Northern Europeans, like in much of Greece as a result of the Slavic expansions during the Early Middle Ages, but most cannot be explained in this way.

Secondly, Balto-Slavic, Celtic and Germanic are not more closely related to each other than to some of the other late PIE branches. For instance, Balto-Slavic is considered far more closely related to Indo-Iranian than to Celtic, which is generally seen as a sister branch to Italic. Therefore, if Balto-Slavic and Celtic derive from a homeland on the Pontic-Caspian steppe, then logically this is also where we should look for the origins of Indo-Iranian and Italic.

So as far as the late PIE homeland is concerned, thanks to ancient DNA, the debate is now practically over. But the PIE homeland debate is still wide open, or so we're told.

Apparently, Mathieson et al. 2017 aren't comfortable with putting the PIE homeland on the Pontic-Caspian Steppe because they can't find any evidence in their ancient DNA dataset of a significant migration through the Balkans that would potentially bring Anatolian languages from the Pontic-Caspian steppe to Anatolia. From the paper:

One version of the Steppe Hypothesis of Indo-European language origins suggests that Proto-Indo European languages developed in the steppe north of the Black and Caspian seas, and that the earliest known diverging branch – Anatolian – was spread into Asia Minor by movements of steppe peoples through the Balkan peninsula during the Copper Age around 4000 BCE, as part of the same incursions from the steppe that coincided with the decline of the tell settlements. [51] If this were correct, then one way to detect evidence of it would be the appearance of large amounts of characteristic steppe ancestry first in the Balkan Peninsula, and then in Anatolia. However, our genetic data do not support this scenario. While we find steppe ancestry in Balkan Copper Age and Bronze Age individuals, this ancestry is sporadic across individuals in the Copper Age, and at low levels in the Bronze Age. Moreover, while Bronze Age Anatolian individuals have CHG/Iran Neolithic related ancestry, they have neither the EHG ancestry characteristic of all steppe populations sampled to date [20] , nor the WHG ancestry that is ubiquitous in southeastern Europe in the Neolithic (Figure 1A, Supplementary Data Table 2, Supplementary Information section 1). This pattern is consistent with that seen in northwestern Anatolia [11] and later in Copper Age Anatolia [23], suggesting continuing migration into Anatolia from the East rather than from Europe.

And this...

On the other hand, our data could still be consistent with the Steppe-Balkans-Anatolia route hypothesis model, albeit with constraints. It remains possible that populations dating to around 1600 BCE in the regions where the Indo-European Luwian, Hittite and Palaic languages were spoken did have European hunter-gatherer ancestry. However, our results would require that such ancestry was not ubiquitous in Bronze Age Anatolia, and was perhaps tightly linked to Indo-European speaking groups. We predict that additional insight about the genetic origins of the potential speakers of early Indo-European languages will be obtained when ancient DNA data become available from additional sites in this key period in Anatolia and the Caucasus.

But I'd say the authors are taking that one particular version of the Steppe Hypothesis way too seriously. They might even be implying things that the creator(s) of the said hypothesis never posited.

Why do they seemingly expect a massive surge of steppe admixture into the Balkans during the Copper Age? If the steppe people are just shooting through the Balkans on their way to Anatolia, why would they leave a lot of admixture along the way? And if the locals are abandoning their tell settlements and running for the hills as far away from the oncoming steppe invaders as they can, how exactly would they acquire steppe admixture? Osmosis or what?

The Balkans is not Northern Europe, and the hypothesized migration of the proto-Anatolians from the Pontic-Caspian Steppe to Anatolia through the Balkans was never, as far as I know, meant to parallel the massive Corded Ware expansion across Northern Europe. In other words, why should all of the early Indo-European expansions have been of the same character, especially considering that they moved into such starkly different areas of Eurasia?

Indeed, as Mathieson et al. 2017 point out in the quote above, the evidence for the fleeting presence of steppe peoples in the Copper Age Balkans is in their dataset. For instance, in their Varna 1 sample set from Bulgaria, three out of the five individuals show significant steppe admixture. One of these individuals is almost 50% Yamnaya-like. Surely, there's really no need to expect anything more than that when looking for signals of a proto-Anatolian migration from the Pontic-Caspian Steppe to Anatolia.

In fact, even though I do appreciate the incredible work these guys are doing and the data they're making available to myself and everyone else, I suspect that there's a little bit of, shall we say, schadenfreude going on here.

They sequenced all of three Early Bronze Age Anatolians of obscure origin (are they actually suspected Anatolian speakers, like Luwians?), and apparently it's a big deal that they can't find any steppe admixture in Early Bronze Age Anatolia. Come on.

And then we're offered just three Yamnaya samples from the Pontic Steppe in Ukraine. One happens to be a massive outlier towards the Caucasus. Wow, what are the chances of that? And guess what, all three of these Yamnayans are females, so of course we're left wondering about the Y-haplogroups of the Yamnaya males on the Pontic Steppe. What happened to the males? Next paper, that's what.

Update 19//05/2017: Please note that the authors are not holding back any Yamnaya males from Ukraine for a future paper, as per my claim in the last paragraph above. They used what they had for the time being.

Update 21/05/2017: Actually, I suspect that we already have a population from the Bronze Age steppe in the ancient DNA record with a high frequency of Y-haplogroup I2a. See here.

See also...

R1a-M417 from Eneolithic Ukraine!!!11

Ancient herders from the Pontic-Caspian steppe crashed into India: no ifs or buts

Eastern Europe as a bifurcation hotspot for Y-hg R1

Globular Amphora people starkly different from Yamnaya people