Reduction of Yamnaya-like ancestry in North Europe since CWC

Maybe the TRB initially just receded, and the mixing of the CWC and BB with the remnants of the TRB came only a bit later, after these samples. Or maybe they were just way too similar to GAC people. There's certainly quite a lot of overlap between all those North European EEF groups, so I don't think it's surprising that one or more sources may be hidden "within" a larger EEF population source.
 
So, using nMonte and a database of ancient and modern samples, I tried many models of ancestry for Germany CWC people. Unlike what I have previously read as a hypothesis, a mix of basically Balkans_Chalcolithic + Ukraine_N or a mix of Balkans_Chalcolithic + Ukraine_N + Ukraine_GAC both don't work at all (too high distance rate).

Importantly, all the models (no exceptions) with a much lower (<2%) distance need to have Yamnaya to work (not any other earlier or later steppe sample, far less WHG-like or EHG-like sources to its north). Much more interesting is the fact that the best models all involve Ukraine_GAC as the main source of EEF ancestry in CWC, not EEF of Poland (GAC or TRB), Germany (Germany_MN or Alberstedt_LN) or Sweden (TRB). At least for German CWC it's interesting that TRB (from Poland and from Sweden) always yields 0% if you include Ukraine_GAC. If you include it, too, Poland_GAC yields 0% too.

The best combination of ancestral sources (using several Yamnaya sources as possibilities) I could model and test (distance% = 1.2744) was (for German CWC): 63.5% Yamnaya_Kalmykia, 23.7% Ukraine_GAC, 10.8% Yamnaya_Bulgaria, Narva_Lithuania 2.0%

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Curiously, I tried the same model, using several population references, for Bell Beaker France with lots of steppe ancestry, and its results (also reasonably close - ditance% = 1.1063) are very different from those of German CWC. Would that really be likely if, as Eurogenes thinks, Central European BB were basically a branch of CWC + extra EEF? The results were: Poland_GAC 41%, Yamnaya_Kalmykia 27.5%, Yamnaya_Karagash 15%, Yamnaya_Ukraine 15%, Narva_Lithuania 1.3%, Ukraine_GAC 0.2%. Notice: Poland_GAC instead of Ukraine_GAC as the closest proxy of EEF; and a combination of Yamnaya sources (not including Yamnaya_Bulgaria) instead of almost exclusively Kalmykia+Bulgaria in German CWC.

What do you think those resuls may indicate?

If I'm not making some huge mistake (maybe overfitting?), then it seems like the CWC got almost all their EEF along the way even before mixing with GAC and TRB groups (if they eventually did, I don't know). And it also seems to have got just a little bit more WHG-shifted than what would derive from a simple Yamnaya + GAC mix, possibly owing to the route it took to spread westward in North Europe.

I think the Eneolithic R1a from Ukraine already had some EEF. Like around 20%.

I'm guessing CWC didn't mix much and the farmers just perished.
 
I would say, when warmer times returned (and there were more of it than colder periods) pockets of existing farmer communities recover numbers in population faster than CWC. Also, there might have been movement of farming communities from south to north for the same reason. At times of CWC Northern Europe wasn't populated much. So I guess there was room for peaceful farmer migrations North, without typical conquest migration which would register by "scorched earth".

I've checked the numbers and it seems that EEF was rising steadily from CWC through Unetice LBA/BB to Iron Age. In Iron Age I can see also the Caucasian/Anatolian/Armenian farmer component rising in Eastern and South Europe.

That sounds really plausible.
 
I think the Eneolithic R1a from Ukraine already had some EEF. Like around 20%.

I'm guessing CWC didn't mix much and the farmers just perished.

That's a hypothesis I think should be better investigated, too. I don't think, though, that linguistically and genetically it makes sense for CWC to be just a continuation of an isolated Eneolithic Ukraine people with R1a-M417. Using mostly Late Neolithic & Chalcolithic reference populations near CWC, I can't reach results with distance any below <3%, which is probably owed to the fact that perhaps 1000 years or more lapsed between these samples and the CWC, with intervening admixture events, but the best fit I could find necessitates a mix of Khvalynsk_Eneolithic with Ukraine_Eneolithic, which would theoretically fit into my belief that PIE "proper" (not parallel dialects or sister languages) spread to former Sredny Stog people via east-to-west migration and dominance first with Suvorovo-Novodanilovka and later with Yamnaya. All of them, though, require just a little of Balkans_Chalcolithic ancestry and none from Germany_Middle_Neolithic or Poland TRB. Strange, I wouldn't expect that at all... Maybe I still need to understand this modeling thing better. In any case, I think EBA reference samples should work much better and be closer to reality.


distance%=3.0979"

CWC_Germany

Khvalynsk_Eneolithic,42.5
Ukraine_Eneolithic,36.1
Balkans_ChL,21.4
Poland_TRB,0
Germany_MN,0
Narva_Estonia,0

****

[1] "distance%=3.9592"

CWC_Germany

Ukraine_Eneolithic,93.3
Balkans_ChL,6.7
Poland_TRB,0
Germany_MN,0
Narva_Estonia,0
 

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