lauantai 28. joulukuuta 2019

Some ancestral changes in Iron Age Estonia

QpAdm was designed to detect admixtures giving also probability and standard error statistics.  Two kind of parameters are inputted: admixture candidates and outgroup populations.  The result quality depends on both inputted groups.  They can be incomplete in many ways.  Outgroups should represent some ancestral junctions of tested populations, giving ancestral differences.  If there are multiple outgroups representing same ancestral junction they should give a coherent picture.   It is not a  foregone conclusion in every case because every ancestral branch lives its own history.  That is why it is not easy to choose outgroups. Many other problems exist too.  If there are in tested groups several ancestrally close populations there will be big standard errors due to common genetic drift of those groups.  This means that qpAdm is more suitable for testing very ancient admixtures which are distinctly detectable.  Following tests, made using Iron Age populations in the Baltic area, are only directional.     
Iron Age Estonians

                                Estonian_BA / Baltic_IA / Scania_IA
best coefficients:     0.334     0.613     0.053
Jackknife mean:      0.325213405     0.531536401     0.143250193
      std. errors:        0.326     0.452     0.490

chisq: 5.922
tail prob: 0.655969

The result imply that the best available result calls for all three ancestral populations, one from Sweden, but sorting of them is difficult due to largely common genetic drift.

Sample 0LS10 (Kunda, Lääne-Viru. EST IA 770–430 BC H13a1a1a N3a3'5)

                                Estonian_IA / Saami
best coefficients:     0.847     0.153
Jackknife mean:      0.846059225     0.153940775
      std. errors:     0.059     0.059

chisq: 4.147
tail prob: 0.901439

The standard error is much lower due to lesser common genetic drift.  In this case the total error is probably generated by the Finnish admixture in present-day Saami samples.  The eastern admixture of 0LS10 is very purely eastern and barely shows any Finnish ancestry.  Would I say that it is question about proto-Saami ancestry...

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