The Kura-Araxes people deserve better

When discussing the Kura-Araxes culture and its people it's important to understand these key points:

- there is Eastern European steppe ancestry in Kura-Araxes samples, and if you're not seeing it then you're not looking hard enough

- Armenian Kura-Araxes samples are mainly a mixture between three different groups currently best represented in the ancient DNA record by ARM_Areni_C, IRN_Hajji_Firuz_C and RUS_Darkveti-Meshoko_En

- ergo, most of the steppe ancestry in the Kura-Araxes population of what is now Armenia must have been mediated via local Chalcolithic groups like ARM_Areni_C

- Kura-Araxes samples show Mesopotamian-related ancestry, and this mustn't be ignored.

Oh, you don't believe it because you just read a big paper in Science claiming otherwise?

Well, the authors of that paper, Lazaridis, Alpaslan-Roodenberg et al., used distal mixture models to study the ancestry of their Kura-Araxes samples, and such models can miss important details.

Consider these three proximate mixture models for a relatively high quality and very homogenous Kura-Araxes sample set from the aforementioned paper. They were done with the qpAdm software

ARM_Kura-Araxes_Berkaber
ARM_Areni_C 0.239±0.068
IRN_Hajji_Firuz_C 0.379±0.068
RUS_Darkveti-Meshoko_En 0.382±0.054
P-value 0.285122 (Pass)
Full output

ARM_Kura-Araxes_Berkaber
IRN_Hajji_Firuz_C 0.569±0.051
RUS_Darkveti-Meshoko_En 0.363±0.058
RUS_Progress_En 0.068±0.020
P-value 0.20306 (Pass)
Full output

ARM_Kura-Araxes_Berkaber
IRN_Hajji_Firuz_C 0.531±0.060
RUS_Darkveti-Meshoko_En 0.469±0.060
P-value 0.0132579 (Fail)
Full output

Some caveats apply. For instance, the pass threshold (P-value ≥0.05) is arbitrary. But the point is that the models look much better with steppe-related and steppe reference populations (ARM_Areni_C and RUS_Progress_En, respectively).

Moreover, the unique and vital Darkveti-Meshoko population is represented by just one individual. I also have the genotypes of his brother and sister, but relatives aren't allowed in these sorts of tests.

Including a singleton in the analysis means that I can't use the inbreed: YES option, which apparently can be a bad thing. Nevertheless, these models do look very solid.

Indeed, I can also model ARM_Kura-Araxes_Berkaber as practically 100% RUS_Maykop_Novosvobodnaya, perhaps with some excess ARM_Areni_C-related input.

ARM_Kura-Araxes_Berkaber
ARM_Areni_C 0.094±0.087
RUS_Maykop_Novosvobodnaya 0.906±0.087
P-value 0.284259 (Pass)
Full ouput

This makes good sense, because RUS_Maykop_Novosvobodnaya can also be modeled solidly as a mixture between IRN_Hajji_Firuz_C, RUS_Darkveti-Meshoko_En and RUS_Progress_En.

RUS_Maykop_Novosvobodnaya
IRN_Hajji_Firuz_C 0.614±0.056
RUS_Darkveti-Meshoko_En 0.307±0.064
RUS_Progress_En 0.080±0.022
P-value 0.141468 (Pass)
Full output

I don't know whether the genetic relationship between ARM_Kura-Araxes_Berkaber and RUS_Maykop_Novosvobodnaya shown in my model is due to Maykop ancestry in the former. It might just be a coincidence in the sense that the same or similar processes led to the formation of both groups. Feel free to let me know your thoughts about that in the comments.

The fact that the Kura-Araxes people harbored steppe ancestry might be very important in the debate over the location of the so called Indo-Anatolian homeland. For instance, it's possible that the proto-Anatolian language spread from the North Caucasus into Anatolia via the Kura-Araxes culture.

But, admittedly, such a solution doesn't have strong support from historical linguistics data, which suggest that the Indo-Anatolian homeland was located in what is now Ukraine and that Anatolian speakers entered West Asia via the Balkans:

Indo-European cereal terminology suggests a Northwest Pontic homeland for the core Indo-European languages

See also...

R-V1636: Eneolithic steppe > Kura-Araxes?

Dear Iosif...Yamnaya

But Iosif, what about the Phrygians?

Armenian Highland population prehistory

A new preprint at bioRxiv claims that some sort of large-scale population movement resulted in the spread of Sardinian-like ancestry into both the Armenian Highland and East Africa during or just after the Middle-Late Bronze Age. See Hovhannisyan et al. here.

In all seriousness, my suggestion is that the authors should familiarize themselves with the scientific concept of the sanity check and then try again.

For what it's worth, here's a brief outline of the population history of the Armenian Highland based on what I've learned about the topic from ancient DNA in recent years:

- overall, the Neolithic populations of the Armenian Highland were surely very similar to the Caucasus_lowlands_LN samples from what is now Azerbaijan from the recent Skourtanioti et al. paper (see here)

- Chalcolithic era migrations from the Pontic-Caspian steppe and/or the North Caucasus introduced steppe ancestry to the Armenian Highland, bringing at least some of its populations closer genetically to those of Eastern Europe (a somewhat outdated but still useful blog post about this subject is found here)

- population expansions during the Early Bronze Age associated with the Kura-Araxes cultural phenomenon, which may have originated in what is now Armenia, resulted in a resurgence of indigenous Caucasus hunter-gatherer (CHG) ancestry across the Caucasus, as well as its spread to many other parts of West Asia (see here)

- another significant pulse of Eastern European admixture affected the Armenian Highland during the Middle-Late Bronze Age and Early Iron Age (see here)

- it's not yet completely clear what happened in the Armenian Highland during the Iron Age in terms of significant genetic shifts, due to the lack of ancient human samples from the region dating to this period, but it's still possible that the speakers of proto-Armenian arrived there from the Balkans at this time

- the present-day Armenian gene pool is the result of the processes described above, as well as later events, such as those associated with the Urartian and Ottoman Empires.

Indeed, it's probably not a coincidence that present-day Armenians cluster more or less between the prehistoric populations from the Armenian Highland and surrounds in the Principal Component Analysis (PCA) below.

To see a more detailed and interactive version of the plot, copy paste the data from the text file here into the relevant field at the Vahaduo Globabl25 PCA Views here.

Citation...

Hovhannisyan et al., AN ADMIXTURE SIGNAL IN ARMENIANS AROUND THE END OF THE BRONZE AGE REVEALS WIDESPREAD POPULATION MOVEMENT ACROSS THE MIDDLE EAST, bioRxiv, Posted June 24, 2020, doi: https://doi.org/10.1101/2020.06.24.168781

See also...

Armenian confirmation bias

Perhaps a hint of things to come

Understanding the Eneolithic steppe

R1b-M269 in the Bronze Age Levant

The new Harvard genotype datasets that I blogged about recently include a couple of potentially very useful samples from the Levant dated to 1400-1100 BCE. Search for IDs I2062 and I1934 in the anno files here. They're both from an archeological paper about a Late Bronze Age (LBA) burial site in what is now Israel that was published back in 2017 (see here).

Surprisingly, individual I2062 is listed in the anno files as belonging to Y-haplogroup R1b1a1a2, which is also known as R1b-M269. The reason that this is a surprise to me is because R1b-M269 is closely associated with the Bronze Age expansions of pastoralists from the Pontic-Caspian steppe in Eastern Europe, and these expansions didn't impact the Levant in any direct or significant way.

The Y-haplogroup assignment may or may not be correct. Sometimes the Y-haplogroups in these sorts of datasheets are indeed wrong. Unfortunately, as far as I know, the BAM file for I2062 isn't available anywhere online, so I can't check whether he does really belong to R1b-M269. But, intriguingly, his autosomes do show a subtle signal of Yamnaya-related ancestry from the Pontic-Caspian steppe that is missing in earlier ancients from the Levant.

To characterize his genome-wide ancestry, I first ran a series of unsupervised and supervised analyses with the Global25/nMonte3 method (using this datasheet). For the sake of simplicity, I narrowed things down to the mixture models below based on three reference populations each. Levant_ISR_C is made up of Chalcolithic samples from Israel. The identities of the other reference sets should be obvious to most readers. If confused, feel free to ask for more details in the comments below.

Levant_ISR_MLBA:I2062
Levant_ISR_C,66.8
IRN_Seh_Gabi_C,27
Yamnaya_RUS_Samara,6.2
[1] distance%=1.8905

Levant_ISR_MLBA:I2062
Levant_ISR_C,66.2
Kura-Araxes_ARM_Kaps,30.2
Yamnaya_RUS_Samara,3.6
[1] distance%=2.0856

Levant_ISR_MLBA:I2062
Levant_ISR_C,67.8
Kura-Araxes_RUS_Velikent,31.8
Yamnaya_RUS_Samara,0.4
[1] distance%=2.1738

To further confirm the reliability of my models, I tested them with the formal statistics-based qpAdm software. As far as I can tell, the output from qpAdm looks very solid across the board.

Levant_ISR_MLBA_I2062
IRN_Seh_Gabi_C 0.193±0.052
Levant_ISR_C 0.710±0.038
Yamnaya_RUS_Samara 0.098±0.026
chisq 9.304
tail prob 0.67676
Full output

Levant_ISR_MLBA_I2062
Kura-Araxes_ARM_Kaps 0.249±0.076
Levant_ISR_C 0.681±0.051
Yamnaya_RUS_Samara 0.071±0.035
chisq 11.101
tail prob 0.52032
Full output

Levant_ISR_MLBA_I2062
Levant_ISR_C 0.661±0.042
Kura-Araxes_RUS_Velikent 0.339±0.042
chisq 7.979
tail prob 0.844942
Full output

Admittedly, even though I2062 can be modeled with Yamnaya-related admixture, he doesn't need to be. Indeed, his ratio of this type of ancestry varies significantly between the models, from around 10% to nothing. This appears to be dependent on the geography of the non-Levant and non-Yamnaya reference populations; the closer they are to the Pontic-Caspian steppe, the smaller the ratio of Yamnaya-related ancestry in I2062. I'd describe this as an artifact of the isolation-by-distance phenomenon, and it totally makese sense, but it prevents me from confirming beyond any doubt that I2062 does harbor genome-wide steppe ancestry. Unfortunately, individual I1934 doesn't offer enough data to be analyzed with the same methods.

Samples associated with the Kura-Araxes or Early Transcaucasian culture are particularly strong references for the eastern ancestry in I2062. This probably isn't a coincidence, and it might also explain his Y-haplogroup, because, at its maximum extent, the territory occupied by the Kura-Araxes culture stretched all the way from the Pontic-Caspian steppe to the southern Levant. The map below is from Wilkinson 2014.

See also...

Downloadable genotypes of present-day and ancient DNA data

Early chariot riders of Transcaucasia came from...

R-V1636: Eneolithic steppe > Kura-Araxes?