(map created by Rob)
The new Wang et al. (2018) paper has opened up a new can of worms in the formation of Eneolithic steppe cultures. It also has some major gaps that leave room for a lot of speculation. What would be most helpful is samples from the Piedmont between 6000 BCE and 4500 BCE to see the formation of the Prikaspiiskaya Culture.
Vibornov (2016) reiterates a common theme suggesting that this culture originates on the Don at 5500BCE, but migrations from West Asia are also suggested. The only problem with this is that we have samples from Eastern Ukraine, and they are nothing like this. I would find it highly unlikely that this group originated close to here. I think the origin will be closer to the Caucasus, mixing with an early farming wave. Which direction they came from is more of the debate here.
The Meshoko samples presented are far too Anatolian to matter anything to the Steppe Eneolithic, and with good reason. They are 1500 years or more after farmers appear in the region and begin at the tail of Shulaveri-Shomu, which had increased contacts with Halaf in levels IV and V, near the end of the culture (Hamon, 2008). This likely increased the Anatolian ancestry of these farmers. Meshoko-Darkveti is also influenced by local potters from the Don, one site that saw a deterioration of pottery quality in later sequences (Kozintsev, 2017).
Rob has also provided me with a nice graph here showing the Mesolithic through to the EBA for the region in question.
Not only this, but the fact that the Prikaspiiskaya differs and drifts towards the South and Eastern Caspian in terms of mud-brick architecture, lithics, and also domesticates. The early Jeitun culture is the first to be heavily dependent on sheep and also goats (Harris et al, 1996), differing from other traditions, such as Mesopotamians with their cattle and pigs. Prikaspiiskaya currently only shows sheep and goats as domesticates. Perhaps another clue as to where the contacts came from.
There are curious cases of potentially unrelated farming groups passing through the West Caspian region. Hajji Firuz shows evidence of an earlier group with different pottery. In Azerbaijan, local farmers, at least by 5900BCE could be the source of Shulaveri-Shomu, rather than farmers coming directly from Mesopotamia. Hajji Firuz has a good amount of Anatolian ancestry, probably far too much for Mesopotamians to make up much of the ancestry of even something as late as Meshoko. I would expect Shulaveri-Shomu to be even more shifted towards Iranian farmers, and even West Siberia Neolithic samples. I expect that Jeitun may be not much different from later farmers in the region, potentially between groups like Tepe Hissar ChL and Geoksiur EN. These groups look more like Iran_LN plus some CHG and West Siberia N-related ancestry.
Without these samples it is really hard to say what happened for sure, with regards to direction of flow. Is Prikaspiiskaya like South Caspian farmers, with the samples we have containing back-flow admixture from Khvalynskaya? It is hard to say. I think the big thing to take away is that this movement from the south happened after 6200BCE, but before 5500BCE. The Don should be ruled out with the Ukrainian samples. That leaves us the first Shulaveri-Shomu, or a Jeitun or Kelteminar-related group somehow navigating to the region, either through the Caucasus, via Azerbaijan, by boat, or around the East Caspian. The interesting link in this might be Caspian fluctuations that brought about an increase of 8m in depth (Naderi Beni et al, 2013) for the Caspian at the beginning of the Jeitun, and ended at the time Prikaspiiskaya appears. There is also evidence of a hiatus at Jeitun just before the beginning of the Prikaspiiskaya. Could some have traveled North? They got their sheep somewhere, and it wasn’t from fully developed SS.
Just to test this out, I tried a few runs with qpGraph, to see if these Eneolithic samples from the Piedmont want admixture from hunter-gatherers, like CHG, or from farmers around the South Caspian. I chose Tepe Hissar and Geoksiur as my stand-ins, as there is not much better of an option at this time. The results were pretty interesting.
I started by making a base graph that included Chimp, West_Siberia_N, EHG, CHG, Tepe_Hissar_ChL, and Geoksiur_EN.
This graph basically just left us with Geoksiur wanting some extra admixture from a population closer to West_Siberia_N, so that is where I went with the second graph.
With this all set, I went ahead and added Progress_Eneolithic. The first run, with them unattached, showed the strongest Z-score with EHG. So, that is where I placed them for the first run.
Interestingly, this graph left the most significant Z-scores wanting admixture from a source most like Tepe_Hissar, rather than CHG or even Geoksiur.
After completing this graph, Progress is now wanting some addition CHG. For the last graph, I put in an admixture edge from CHG, to Progress_Eneolithic.
What we are left with, is a population that is mostly represented by EHG, with minor CHG, and a good chunk of farmer from the South Caspian. This could represent several things. One is that the hunter-gatherers before 5500BCE were EHG with just minor CHG. Two, could be that the farmers coming in were more CHG-like than Tepe_Hissar, or lastly, that these samples have some back-flow from Khvalynsk, making them more northern. With the samples available, it is really a guessing game. Nothing can be said for certain until there are samples all around the Caspian from 6500-5000BCE. Then, we should know exactly what happened.
Just to try to look for a different result, I tried adding Ust-Ishim to the next set of graphs to see if anything changed. The graphs were as follows:
As can be seen from the above graphs, adding Ust-Ishim really caused no issues here. The output is basically identical from the first, less complex run. Next, I wanted to explore the route from the South Caspian, around the East Side of the Caspian Sea. For this, I figured that Iranian Mesolithic samples from Hotu and Belt Cave would do. They do not have much coverage, but beggars can’t be choosers here.
Firstly, I wanted to explore just how Iran_Meso compares to Ganj_Dareh_N with a series of graphs. They went as follows:
I was quite surprised to see the extra non-basal admixture into Iran Meso was more like EHG than West_Siberia_N. We need more sampling, but a pop closer to EHG down the Caspian is a possibility. Lots could’ve happened between then and the Eneolithic of Central Asia to create an excess of West_Siberia_N ancestry.
The next step was to use simple graphs to see how Progress Eneolithic would look by adding more “Eastern options” for admixture. For this one, I used Iran_Meso, and Eneolithic Caucasus as admixing sources. Ukraine_N was also added, as a Don HG reference to see if it matches those archeological best-guesses.
As the above graph progression shows, overall, the genetic make-up of the Progress samples best match the samples outside of the Caucasus. Minimal admixture from Meshoko is all that this graph produced. For the next set, I decided to add CHG. This made it much more complicated, but the overall outcome didn’t change, with CHG only taking a bit from Iran_Meso and Caucasus_Eneolithic.
f3-ratio Test for Admixing Source
Below, testing for an admixing source via f3 revealed no significant stats showing that one is a preferred source in a single event.
With all of the evidence here, along with the fact that Iran_Meso seems to fall on a Ganj_Dareh_N > EHG cline, rather than with West_Siberia_N, the question may become how much of the EHG is from North of the Caspian, with Progress? Is it all from Khvalynsk, local HG, or did it all come from East of the Caspian. Some of this could also be due to the excess ENA in West_Siberia_N not being present in Central Asia. Lithics point to movements from the South, towards the Urals, from at least the 8th Millenia BCE. Could some have come with domesticated animals? It certainly seems plausible, as these domesticates in the steppes do not include pigs, which was common in the Caucasus and Europe. Sheep do not occur in the wild in the Urals and European steppes. These are clearly brought in by other people. Could this dead-end R1b be from East of the Caspian? I suppose it is possible with R1b being in Botai, in northern Kazakhstan. R1b being rooted in Central Asia is not a new idea. It could be there as much as 30KYA, or more.
This is all just several possibilities. Considering the lithics are not linked to the Caucasus, but possibly to Central Asia, and the clear links with pottery and even the limited domesticates are pointing there too. FrankN has done a good job summarizing the southern links with the Steppe Eneolithic and checking out that would be of interest to some (www.adnaera.com). Kelteminar is speculated to originate from the South Caspian, in Iran. They very well could be just like the Hotu and Belt Cave samples. Clearly, samples from all around the Caspian, including the Caucasus, are needed between 6500BCE to 5000BCE to really say what happened. Until then, none of us can really say for sure. Hopefully, more sampling will help to shed light on just who these Eneolithic Steppe folks were.
Harris et al (1996) Jeitun: Recent excavations at an early neolithic site in Southern Turkmenistan. https://www.researchgate.net/publication/271947810_Jeitun_Recent_Excavations_at_an_Early_Neolithic_Site_in_Southern_Turkmenistan
Naderi-Beni et al (2013) Caspian sea-level changes during the last millennium: historical and geological evidence from the South Caspian Sea. https://www.clim-past.net/9/1645/2013/cp-9-1645-2013.pdf
Narasimhan et al (2018) The genetic formation of South and Central Asia. https://www.biorxiv.org/content/10.1101/292581v1
Szymcsak et al (2006) Exploring the neolithic of the Kyzyl-Kums. https://www.academia.edu/2765764/Exploring_the_Neolithic_of_the_Kyzyl-kums_Ayakagytma_The_Site_and_other_collections
Vybornov et al (2015) The origin of farming in the Lower Volga region. https://revije.ff.uni-lj.si/DocumentaPraehistorica/article/view/42.3/5018
Wang et al (2018) The genetic prehistory of the Greater Caucasus. https://www.researchgate.net/publication/325189972_The_genetic_prehistory_of_the_Greater_Caucasus