If Tarand graves (culture that is clearly Baltic Finns) new research brings up N folk that autosomally look exactly like Baltic_IA, then the case is settled.
1. What case?
I would not care that much about autosomal comparisions... because the main tendency is that neighbours have the same, but slightly different autosomal genes. In other words - it means nothing, compared to y-dna, besides mtdna of Baltic region is present all over Europe.
2. Yeah, I get it now - I've jumped on gun of "Erzya" without noticing "like".
3. When exactly? And at what time? What type of N? Could you cite a link, please? I'm genuinelly interested. But I don't think, that it is the case, though - more detailed explanation in 5.
The problem with Semigallians is that current history teaches, that they were moving into Latvia from Lithuania only in 5th century or so, but we can let it slide for the sake of argument, as some of the Semigallian settlements were there before that date. I understand, that so far samples from early 5th century AD were predominantly R1a and one sample, doesn't really change main direction for Semigallians/Selonians.
Anyway, I'm not here to prove my point, but learn - my real passion is to get to the root of this and if it is something, that does not corrobate with what I've constructed, I'm more than happy to adapt and change it
4. I'm sorry, but I was not really specific - by "wiped out" I meant, that their manpower(essentially also able to breed men) was not usable to make war and that big part of Curonians moved to Samogitia(and also - to be fair not all of them moved, because some parts of Samogitia consisted of Curonian and Semigallian lands), just like a big part of western Semigallians. Of course, not everyone were wiped out 100% - I'm not making THAT statement, but enough to require influx of fresh settlers from other regions, essentially making locals extinct and their distinct identity in the process.
5. Can't agree on that Semigallians and Selonians are descendants of the same group and came along the same route as Letts-Lithuanians. Nothing supports that thinking.
1) First, their cultural and liguistical commonity points to west Selonians/Semigallians are more related to Prussians, than to Latvians/Lithuanians, or actually - most probably their own center.
Historical vowel shifts in Latvian and Lithuanian languages points to Selonian as local archaical substrate, that is used as a base for modern Latvians-Lithuanians. I have no idea what language used Latvian/Lithuanian ancestors, but IT IS NOT proto-Baltic, as that seems like a construction, that is what happens when Latvian and Lithuanian is cleared of language that used Latvian and Lithuanian ancestors.
2) Then there is other problem - related to theory, of first group of Baltic people arriving from south. It has archeological findings, that points to that direction. In 90s there were publications, of findings of ancient Baltic teeth similarities to Romania region.
https://upload.wikimedia.org/wikipe...svg/1015px-Map_Corded_Ware_culture-en.svg.png
Anyway, it might be possible, that ancestors of Balts initially dispersed to north from Ukraine - that includes those regions from where Latvians/Lithuanians came from, maybe there was some moving back and forth - Golads in Moscow region hardly is an exception. But looking on the dispersal map of Corded Ware culture, Baltic is like an offshot to northern region. And proving, that initial N, that is present in east would mean that it also came from south, but we see, that there are two main groups of dispersal of N in Baltic - one is from Karelia(the term, that also includes central Finland), and other that is nowadays present as a remnant of wave from east.
It would be hard to link that Latvian/Lithuanian belonged to Brushed Pottery culture, so it is belonging to Dniepr-Dvina culture. (Well... there are publications, that points to that Dniepr-Dvina culture link of Latvian/Lithuanian ancestry, but I have no link...)
It corresponds to earliest Lithuanian and Latvian settlements in Latvia and Lithuania. So, it leaves only Selonian-Semigallian group(along wih their southern variations Aukstaitian-Žemaitian) as Brushed pottery group, which was more local and indigenous, compared to Latvian/Lithuanian. It was almost near core of emergence of Balts and also R1a for that matter, too.
Also, it makes no sense to assume, that Brushed pottery came from East, and that applies also to Selonians. A couple of hundreds years without borders, visas and passport control is enough for people to mix - plenty of time for that, but even prior Latvian and Lithuanian ancestor push to west main seeping of N most probably came from ancestors of Latvians/Lithuanians.