The main problem they got is that they have at the Middle Don a non-fitting ratio. Simple put, CHG is still too low in these samples. If they would go to the Lower Don, we will find the complete steppe package, most likely the majority of PIE lineages, around the Sea of Azow and that 6.000-5.000 BC the latest, which means before the branching of any IE lineage. That was the point I'm making and its what I have saying now for quite some time: Sample the Lower Don/Sea of Azow region, its just too obvious that the mixing occured there, because we have actual, archaeological evidence of Southerners coming in, probably along the Black Sea coast. I guess a lot of sites being now underwater, because the sea level was lower back then.
Rakushechny Yar is an absolutely key site:
https://www.academia.edu/31137880/A...zle_of_Neolithisation_in_the_Sea_of_Azov_area
How can they investigate IE and miss all the key cultures for so long?
- Lower Don cultural formations, R. Yar.
- Sredny Stog (proper), Dereivka (Sredny Stog and later phase)
- Corded decorated Balkan groups, Cernavoda and Troy
To even talk about PIE and early IE without those samples is futile. Khvalynsk was always likely a dead end, nothing but an early side branch, which mixed with locals and was later replaced. But some of them wanted desperately to find the roots outside of the confines of Europe in the narrower sense I guess, first in the East, now in the South. Kind of strange to sample everything around first, instead of the core zone.