Comments on the Chart Before Reviewing Yediay et al. (2024)

Comments on the Chart Before Reviewing Yediay et al. (2024)

Before reviewing the recent Yediay et al. (2024) preprint, a few comments about this chart are necessary.

Armenia Middle and Late Bronze Age samples clearly show ancestry from three main sources.

1. Kura–Araxes ancestry

The first component comes from Armenia EBA, associated with the Kura–Araxes culture. This is expected and does not require further explanation.

2. “Anatolia_C” ancestry

The second component is labeled Anatolia_C. At first glance this may seem surprising, but it actually has a straightforward explanation.

The Anatolia_C component largely derives from Neolithic and Chalcolithic populations of historic Armenia, associated with the Chaff-Faced Ware (CFW) cultural horizon. These groups lived before the rise of the Kura–Araxes culture and were also present in what is now Azerbaijan, where they are known archaeologically as the Leyla Tepe culture.

When the Caucasus hunter-gatherer–shifted Kura–Araxes culture expanded from its homeland in the South Caucasus, it did not completely replace these earlier populations. In many areas, they continued to live alongside the Kura–Araxes communities.

When steppe ancestry arrived from the north about 4,500 years ago, these groups most likely entered the region through what is now Azerbaijan, where they encountered the remaining populations associated with the Leyla Tepe culture. After mixing with them and acquiring this Anatolia_C-like ancestry, they moved toward the upper Kura–Debed river region, where they mixed with populations related to Armenia EBA.

Another possible source of Anatolia_C-like ancestry may have been populations living in the southern parts of the Araxes plain.

This pattern was also noted in Skourtanioti et al. (2024). However, the authors interpreted it incorrectly, proposing two separate migrations occurring during the same period—one from Anatolia and another from the steppe. Genetic bloggers had already pointed out earlier that this explanation is unlikely, and Davidski even opened a dedicated discussion thread on the issue.

3. Apparent CWC ancestry

The third component is the so-called CWC ancestry. This is almost certainly not a real signal.

The Corded Ware culture (CWC) is strongly associated with R1a, yet no R1a lineages have been found in Middle and Late Bronze Age samples from the South Caucasus (including Armenia and Georgia).

The reason CWC appears in the model is likely that the steppe groups who migrated into the South Caucasus carried a small amount of WHG-related ancestry. This additional WHG / Ukraine Neolithic hunter-gatherer affinity was already present east of the Azov region even before the formation of the Yamnaya culture.

This additional component could also explain the appearance of I2a2b in ancient Armenia.

It is important to note that CWC is genetically similar to Yamnaya, but it contains roughly:

• about 10% additional UNHG-related ancestry

• about 20% Euro-Anatolian farmer ancestry

Even a very small 1% WHG introgression into a Yamnaya-like population can create a statistical signal resembling 10% CWC ancestry in modeling. Given that MLBA samples already contain excess Anatolian ancestry, it is not surprising that the calculator interpreted this mixture as CWC rather than Yamnaya.

Thus, the CWC component in this case is an artifact of the modeling, although it reflects real underlying genetic processes.

Urartian period samples

A similar situation can be observed in Urartu-period samples, where the Anatolia_C component is higher. This indicates a stronger Neolithic-derived ancestry, while the steppe component is lower.

There is one exception—an outlier individual, who appears to have been a migrant from Etiuni.