"Ancient DNA Reveals Matrilineal Continuity in Present-Day Poland over the Last Two Millennia",
published in October 2014:
http://www.plosone.org/article/info:doi/10.1371/journal.pone.0110839
The study compares samples of fossil mtDNA from Ancient Poland (200 BC - 500 AD) and Early Medieval Poland (950 AD - 1250 AD), with samples of mtDNA from modern populations. Sample sizes are 23 individuals from 4 different burial sites of Ancient (Late Iron Age) Poland and 20 individuals from 2 different burial sites of Early Medieval Poland.
Those relatively small Ancient and Medieval samples were compared to a modern sample of 3595 individuals from 18 ethnic groups (300 Poles, 305 Belarusians, 307 Russians, 300 Czechs & Slovaks, 300 Bosnians, Slovenians & Croatians, 300 Bulgarians, 293 Macedonians & Serbians, 300 Ukrainians, 296 Swedes, 300 Germans, 277 Lithuanians & Latvians, 317 Finns & Estonians.
The study reveals that population of Ancient Poland (200 BC - 500 AD) shares the highest percent of mtDNA haplogroups with modern (in this order when it comes to % of shared DNA): Poles, Czechs, Slovaks, Lithuanians, Latvians.
While the population of Early Medieval Poland (950 AD - 1250 AD) shares the highest percent of mtDNA haplogroups with modern (in this order when it comes to % of shared DNA): Poles, Belarusians, Bulgarians and Ukrainians.
In both cases Ancient and Medieval DNA from territory of present-day Poland resembles modern Polish DNA most. However, Medieval DNA from area of present-day Poland is more similar to this of modern Belarusians, Bulgarians and Ukrainians; while Ancient DNA from area of present-day Poland is more similar to modern Czechs, Slovaks, Lithuanians and Latvians.
Here are the Ancient (stars) and Medieval (triangles) burial sites used in this study:
Stars are Kowalewko (K), Karczyn (KA), Gąski (G), Rogowo (R) - burial sites associated with Przeworsk Culture and Wielbark Culture.
Triangles are Ostrów Lednicki (OL) and Cedynia (C) - Early Medieval burial sites, associated with early history of the Polish Piast Realm:
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Let's also add which of modern ethnic groups examined in this study are least similar to Ancient inhabitants of present-day Poland.
Out of 18 ethnic groups analysed in this study, least similar to population of Late Iron Poland (200 BC - 500 AD) are the following 6:
- Macedonians, Serbians, Belarusians, Finns, Estonians and Germans