keskiviikko 12. elokuuta 2015

New samples from Latvia, Slovakia, Slovenia and Russia/Pinega

My new PCA-plots introduce new samples published by Estonian Biocentre.   I did some modifications to sample sizes in order to avoid oversampling of Estonians, Finns and many other sample groups.   I also removed Uralic and West Siberian populations to achieve more details in Europe.   Use of distant samples, like modern Uralic people, captures usually at least one dimension and shrinks the view of all other European populations.  The main reason to drop Uralic samples was to obtain more east-west resolution in Europe.  A basic rule is that if you use a geographically large data set in studying Europe you get a stable result, but you will lose details.  If you use a local data set you get more details locally, but lose some rare admixtures and you have a risk of getting distorted result produced by local genetic drift.  Which way is better depends on your goals.  I also created a new Finnish group using georgraphically representative samples without splitting into two groups.   This was done to minimize the effect of genetic drift and to see more real differences/similarities in Europe.

Now results show clear western and eastern clines in Europe.  I have no sure explanations why this happens, but perhaps the western cline proves about Megalithic and Bell Beaker elements and the eastern one more about the Bronze Age intrusion of people from East European plain.

Eastern Finnic groups carry bidirectional history, which is seen on dimensions 2 and 3.   It is really pity that we still have to wait for academic Saami samples. We need those samples to prove possible eastern Saami connection which can be rather old considering the large area of this bidirectional result continuing from Eastern White Sea region to Finland.  But we need Saami samples to prove it. 

Eigenvalue for the eigenvector 1 is 2.286778, for the second one 1.353679 and for the third one 1.339063, so dimensions 2 and 3 on plots represent almost equal dependences between samples.  You can also make a live 3d-view using applicable software by downloading 3d-data here.

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