The purpose of this article is to make a case for investigating ties between J-L283 and the Caucasus Hunter Gatherer autosomal genetic component in Yamnaya samples. There is neither hard evidence nor strong circumstantial evidence that J-L283 was present in Yamnaya. However I believe it remains a plausible explanation given the available data, and one worthy of investigating further because of the abundance of recent scholarship and public interest into the origins and supposed migrations of Proto-Indo-European peoples.

A dedicated fund has been established to direct testing in the direction to answer this question, relevant for all J-L283.

Caucasus Hunter Gatherer (CHG) is a genetic lineage that was first identified in 2015 from a study on several modern Western Eurasian populations. The name comes from the region where the first samples were found, Satsurblia cave and Kotias Klde in Western Georgia. These samples have haplogroups J1-Y6305*, and J2-Y12379*.

The following quotes from "Ancient DNA, Mating Networks, and the Anatolian Split", David Anthony (2019):

"These individuals were later found to be quite similar genetically to hunter-gatherers dated to 9100-8600 BC from level IIIb at Hotu Cave and from nearby Belt Cave from northern Iran on the southeastern Caspian coast, located 1300km southeast of the Georgian sites and in a very different ecological setting (Lazaridis et al. 2016).

People with primarily CHG ancestry also lived 750km southwest of Hotu Cave, at Early Neolithic Ganj Dareh near Kermanshah dated 7000 BC (Lazaridis et al. 2016)."

Because people from these regions were found to have CHG ancestry, "a similar CHG population probably was distributed between W Iran and the Caucasus at the beginning of the Neolithic, about 8000 BC".

The Oldest Ancient J-M102 Samples lived in the CHG Zone

The CHG is relevant to J-M102 research because AH2, the oldest J-M102 sample yet found at about 8000 BC, was found near Ganj Dareh. He shares a SNP in common with J-M102* YF13108 from Uzbekistan.

While the J-M205 MRCA, who lived much later in 3700 BC, does not appear to have lived in the CHG zone, the second oldest J-M102 sample did, in sibling lineage J-Z1825.

The second oldest J-M102 sample, I4349, recently split J-M102>Z534>Z1825>Z2453>Y18039>Y31143>BY22519 on YFull with MRCA who lived 7000 BC. He was found in Hajji Firuz Tepe, NW Iran near Lake Urmia and the border of Armenia and Turkey. I'm not sure what date should be used for this sample, I found these in biorxiv "Date of 5887-5724 cal BCE (6915±40 BP, PSUAMS-2126)".

Given that the most ancient samples of J-M102 have been found in the Caucasus Hunter Gatherer zone and that the only basal J-L283 sample so far is an Armenian, it seems plausible that the ancestors of J-L283 who lived during the 4000 year bottleneck between 7700 and 3700 BC, were also living somewhere between W Iran and the Caucasus.

J-L283 a Potential Vector for CHG Ancestry in Yamnaya

Because J-L283>Z622 appears to have somehow migrated from the Caucasus / W Iran to Europe and that the oldest J-L283 sample, A0101, was found in Kudachurt in the North Caucasus (1800 BC), it is worth investigating a possible connection to the Yamnaya, a culture that David Anthony convincingly presents, in "The Horse, the Wheel, and Language", his "revised Kurgan theory", as a vector for Indo-European language and culture to have migrated from the Pontic steppes westward into Europe.

Caucasus Hunter Gatherer is the third genetic component of Yamnaya ancestry, along with Eastern Hunter Gather and Ancestral North Eurasian.

The following quotes from "Ancient DNA, Mating Networks, and the Anatolian Split", David Anthony (2019):

"We do not know exactly where or when the CHG element that was a robust part of Yamnaya ancestry entered the steppes - an important question."

<six pages behind a paywall I cannot read>

"..it was definitely before 4500 BC. Hunter-gatherer populations of the CHG type probably migrated northward into the steppes from the southern end of the Caspian Sea, perhaps during the early Holocene, and were integrated into EGH mating networks that extended down the Volga from the forest zone, producing a hybrid steppe population that was fairly homogenous genetically from the middle Volga to the North Caucasus steppes by 4500-4300 BC."

"But at 4500 BC they had not yet married into the emerging cattle-keepers whose biggest cemeteries were on the Dnieper Rapids, far to the west, as we will see below."

According to the YFull estimates, J-L283 split into a possible  Caucasus remnant and European migrant lineage J-Z622 3700 BC.

Three hundred years later, there were seven separate lineages descending from J-Z622 and all tracing descent to Europe.

These seven lineages are not sibling to one another, but related in the following tree structure:

• J-YP91 Diverse European
• J-Z600
  • J-Z600* Dominican Republic
  • J-Z600* Romaniote Jews
  • J-YP157 Sardinia
  • J-Z585
    • J-Z585* Tuscany
    • J-YP113 Sardinia
    • J-Z615 Diverse European

J-Z615, through its child J-Z597 who likely lived in the Balkans by 2400 BC latest, is the ancestor of the vast majority of modern J-L283 men.

To assess whether or not J-L283 is a good candidate for the CHG component of Yamnaya will require:

1. Targeted WGS testing of individuals belonging to the first six lineages, the origins of which are not reliably known due to lack of samples / tree substructure / length of bottlenecks
2. Paying to access "Ancient DNA, Mating Networks, and the Anatolian Split", David Anthony (2019)

I have set up a J-L283 Research Fund for the express purpose of 1. We have an Azeri who has only tested 12 markers that may be worth considering for additional testing.

If you value this research please consider donating to the fund and my brother will match $10 of the first ten people who donate $25 or more. I will also pay to access the David Anthony article.

If you are a member of one of these six basal J-L283>Z622 lineages, please reach out to your distant STR matches, as identified by Flor and/or myself, to motivate them to NGS test and get on the YFull tree. We don't have time and energy to continually contact your matches, and generally, after trying a few times with no success, move on to assist research into lineages with more interested parties.

Update 4/18/2020

Thanks for the donations to the J-L283 Research Fund. Now that we have some money (though not enough for an NGS test) I've contacted a Circassian and an Azeri regarding testing for the L283 SNP. Waiting on their response.

In the meantime I've found a complete and recent paper by David Anthony pertinent to our investigation, "Archaeology, Genetics, and Language in the Steppes: A Comment on Bomhard".

He writes that it seems more likely that the CHG component that entered the Yamnaya gene pool did so via Hunter Fisher groups of the South Caspian CHG network migrating up the west coast of the Caspian rather than from the Maikop culture, which itself looks to have been founded by the first migrants who introduced farming north of the Caucasus, having skirted around the western end of the Caucasus Mountains along the Black Sea coast.

A central point of his reasoning is that the ratio of Anatolian Farmer to CHG genetic components in Maikop individuals was too high to account for the CHG acquired by the Yamnaya, whose only 10-18% of Anatolian Farmer is believed to have been acquired further west:

But if Wang et al. 2018 are correct, if the Anatolian Farmer element in Yamnaya came from mating between steppe people and late Tripol’ye or Globular Amphorae farmers, then the CHG genetic element in Yamnaya, more than half of Yamnaya ancestry, could not have been heavily admixed with additional Anatolian Farmer ancestry.

Yamnaya had a minor component of Anatolian Farmer ancestry, 10-18%. If most of it came from Europe then the CHG that was so prominent in Yamnaya ancestry must have been a relatively un-admixed variety of CHG, with a low percentage of Anatolian Farmer ancestry.

This un-admixed kind of CHG disappeared after about 5000 BC in the Caucasus and northwestern Iran, according to Wang et al. (2018) combined with Lazaridis et al. (2016) and the forthcoming Naramsimhan et al. (2018 posted on bioarxiv). After about 5000 BC Anatolian Farmer ancestry spread east through eastern Anatolia and Transcaucasia (Areni-1, Armenia) into Iran (Seh Gabi) while CHG ancestry spread westward into Anatolia and the Levant. All tested individuals dated after 5000 BC in the Caucasus and western Iran showed CHG & Anatolian Farmer admixture on a cline across Iran with greater Anatolian Farmer ancestry in western Iran and the Caucasus and less to none in eastern Iran (Narasimhan et al. 2018). After this mixing of populations happened, the un-admixed type of early CHG ancestry probably survived only in small isolated populations...

CHG in the steppes 6000-4000 BC

The variety of CHG that constituted more than half of Yamnaya ancestry could have been the Mesolithic/Early Neolithic variety, like Hotu Cave or Kotias Cave, not yet admixed with Anatolian Farmer ancestry. If the CHG element in Yamnaya came from a non-admixed CHG population of this kind, they could have walked into the steppes from northwestern Iran/Azerbaijan at any time before about 5000 BC—before admixture with Anatolian Farmers began. The easiest path into the steppes from the Caucasus skirts the eastern end of the North Caucasus ridge, where there is a level plain between the mountains and the Caspian Sea. No such plain exists at the western end of the mountain range, where mountains plunge into the Black Sea. - David W. Anthony, The Journal of Indo-European Studies, "Archaeology, Genetics, and Language in the Steppes: A Comment on Bomhard" (2019)

We don't yet have any ancient J-L283 samples before 1800 BC nor a branching point on YFull before 3700 BC that could delineate a North Caucasus migration vs a South Caspian remnant. I do not study the YFull date estimation technique but I have heard others mention that some estimates might be underestimates.

If we ever find a pre J-L283 ancient sample from W Iran / Azerbaijan, ancient or modern diversity between the Caspian/Pontic Steppes in J-L283* or J-Z622* and/or if the J-L283 formation date on YFull gets pushed back, we will have data to compare.

There is a new Russian sample (unknown location in Russia) not yet marked with the Russian flag on YFull in J-L283>Z622>YP91>YP61 however the MRCA lived 1200 BC and so would not be very informative for determining where YP91 itself lived during its bottleneck 3400-2500 BC. However, if the yet untested Polish cluster ends up also being YP61* this subclade will then have high diversity between Poland and Russia.