Baltic BA vs Baltic HG
One of the false information that keeps being repeated is the supposed Baltic HG admixture in the Bronze Age Baltic population. I've even seen people who instructed others to use Baltic_LVA_HG as a source of the so called "Balto-Slavic drift" in their models.
If true, such admixture would make Baltic BA a hard-core north-east European population, and by extension it would anchor the Slavs to the northern Belarus or even north-western parts of Russia. Maybe that's why this idea is so popular?
But the problem is that it ignores the data we have had for a long time.
In the Baltics, a sudden shift towards Eastern Hunter-Gatherers was observed in the Middle Neolithic, as evidenced below:
| Target: Baltic_LVA_MN Distance: 1.9079% / 0.01907883 | |
|---|---|
| 50.2 | RUS_Karelia_HG |
| 49.8 | Baltic_LVA_HG |
It would be reasonable to expect that Baltic BA also has additional EHG admixture, but nor Baltic BA, nor Balts, nor Slavs have it.
Mittnik et al. made an attempt to model Baltic BA as a mixture of Baltic LN and Narva populations. Such model was rejected by qpWave:
Baltic_BA Baltic_LN Narva 1.18E-255 1.14E-02 rejected rejectedLast but not least, it takes only few G25-based plots to be sure that Baltic HG did not contribute to the later Bronze Age population in any substantial way:
Comments
"The people supporting a homeland of Slavs in Belarus/North Ukraine here are not claiming Slavs were identical to Balt_BA. I actually various times told people better not to use Balt_BA samples to model Proto-Slavic ancestry among modern-day Slavs. The ancestors of Slavs and Balt_BA were still part of a close related genetic cline but Balt_BA was on the northeastern end of it and Proto-Slavs seemingly on the southwestern end of it based on early Slavic genomes. This is well visible in the West Eurasia Global25 PCA were Balt_BA is extremely shifted towards Baltic_HG (even much more so than modern-day Balts) whereas early Slavs are much less shifted in this direction and much closer to the typical Steppe-GAC-cline of North Europeans but still with extra HG. On the North Eururope Global25 pca early Slavs are on the otherside much closer to Balt_BA because this PCA is drift-specific so even if Balt_BA was not ancestral to Proto-Slavs and quite different it is the genetically closest group sampled so far (especially Balt_LTU_BA)".
Good that at least he's aware that there is a SW-NE cline. Questions "how did it form?" and "where did the Slavs come from?" have a common answer.
"The ancestors of Slavs and Balt_BA were still part of a close related genetic cline but Balt_BA was on the northeastern end of it and Proto-Slavs seemingly on the southwestern end of it based on early Slavic genomes".
How could the southwestern end of such a cline fall out in Belarus?
Roman conquest perhaps?
On a serious note - you're starting to ask the right questions.
The other side of the cline could not form in Belarus, nor in Ukraine. And not even in Poland. But that's a topic for one of the two most important posts. The other one will be about the origin of this "Balto-Slavic drift" and Baltic_BA. So... stay tuned.
The migration of shepherds closed the gene pool of Central Europe. This pool contained the genes of hunters, farmers and shepherds. There was a particular group among the hunters, different from the WHG, SHG and EHG, whose mutations were characteristic of the later Baltic BA, that is, the Balto-Slavic drift. The homogenization of this gene pool has started since the CWC. As a result of this homogenization, lineage lines are formed, rich in the hunting genes characteristic of the Baltic BA. We know these families from genomes from the areas of early brown Poland, represented e.g. by individuals N47, N49, and I6579. Spiginas2 could also belong to such a lineage, and his lineage could have migrated to Pribaltica, where it underwent a genuine genetic drift, exposing old hunting genes. This is how Balitc BA was born.
After the population increased, the Baltic BA individuals - in Pribaltica and the surrounding area - began to homogenize with the gene pool of the early CWC present here. And by migrating to the east, they assimilated a population that looked genetically like CWC/Steppe MLBA. These processes produced genomes similar to today's Estonians who lie on the PCA between CWC/Steppe MLBA and Balitc BA. Subsequently, migrations from the West Slavic areas of the Roman period and the Middle Ages pulled off today's Balts and Eastern Slavs to their current position in the PCA.
Spiginas2 is not ancestral to Baltic_BA. It's a Tollense-like or Mokrin-like population from the Carpathian Basin mixed with local hunter-gatherers from the Baltics (EHG-like, Volosovo-like Latvia_MN).
Amplification of one of the ancestries is physically impossible.
Baltic_BA doesn't have any local admixture.
There are some differences between Baltic_BA groups that may suggest slight admixture from a CWC-like source. Nothing important.
Estonians (sans their Germanic and Uralic admixtures) are part of the Balto-Slavic cline.
I don't know if it was a large-scale migration. It rather looks like an isolation-by-distance - a smooth gradient from the Baltics all the way to the Balkans. This gradient is nothing new as it existed already in the Bronze Age.
Shift from Baltic_BA to modern Balts may be due to a "last-minute" movement of Balts-proper from the area to the south of the Baltic countries (after all there are samples from Viking Age Gotland, which are nearly identical to Baltic_BA, so pure "Baltic_BA" was still around in the Middle Ages).
I also meant the small Baltic BA founding group and its isolation by distance. The founding group is unrepresentative of the original population and is always less genetically diverse than it. In a small isolated population, genetic drift and pedigree collapse also perpetuate old mutations, which could have led to an excess of WHG.
And a drift in a small population can't led to an excess of WHG (besides some purely hypothetical scenarios, think "spherical cow in a vacuum").
Around Carpathians it was diluted by the neolithic and epi-CWC pops.
So now we are waiting for the earlier population from the Carpathians, abundant in Baltic BA. The Nitra group seems to be a good candidate.
Parastais:
"It is unlikely Baltic_BA from Estonia or Latvia to have anything to do with Polish genetics. So, Poles can't have 50% of it.
However similar genes to Baltic BA, but less WHG were likely spread accross East European plain and different complex migration processes were happening. Some of these similar populations ended up in modern Poles, some in modern Balts, but majority of "Baltic BA" genes in Lithuanian or in Polish is not from Latvian and Estonian BA folk".
Don't get trolled by them.
Parastais, I don't understand what you are talking about. The Baltic component, whatever we call it, is one and it is common (ancestral) to all Balts and Northern Slavs.
Kusznierewicz:
"Expansion of Slavic languages took place in an area already occupied by speakers of the Baltic languages [49,50]. Despite significant linguistic divergence between extant East Baltic and Slavic languages (Fig 1) [7], Baltic populations are genetically the closest to East Slavs (Fig 2A and 2B, Table K in S1 File) [45,64–66] and here we found that they bear the highest number of shared IBD segments with the combined group of East-West Slavs (Fig 4, Table G in S1 File). The presence of a substantial “Baltic substratum” in the genomes of extant Slavs within East Europe might in part explain their genetic closeness to each other and difference from some neighboring non-Slavic groups".
https://1.bp.blogspot.com/-3pW4XfigTdQ/YJ9mbxo2H1I/AAAAAAAAAcc/6u7Oa0iiGVYFpGIlWHsAPaKLOxR2yweHwCLcBGAsYHQ/s16000/Vahaduo_Custom_PCA%25285%2529_clines.png
Because according to Hellenthal, the Greek Slavs were Polish-like, and this also be confirmed by the recent study by Galicznik.
But I can tell you that the northernmost (or easternmost as some want) medieval Slavs from the Balkans were Czech-Ukrainian-Slovenian-Hungarian-like.
Which is nothing surprising when you consider this Balkan cline.