Sigtuna, Sweden Viking Age

I was lucky to get new samples (ENA bam-files) from the study Genomic and Strontium Isotope Variation Reveal Immigration Patterns in a Viking Age Town, Maja Krzewiska et al. 2018.  The study included seven high quality late Viking Age samples from the Swedish town Sigtuna.  Sigtuna was an important market place, founded 970 ad and continued to be important to the 13th century.  These seven samples are good enough to make admixture analyses.  I have made admixture analyses using Dna.Land's software, look here,  and I see no reason to change my methods.   These samples are only 900-1100 years old and it is reasonable to suggest that modern references are suitable for this purpose, especially because with the modern reference the genome quality is is much better than using other ancient samples as references.

Why admixture analyses, why not tests utilizing genetic drift, like qp3Pop and qpDstat?  Both above-mentioned methods or other tests like IBD and IBS statistics, as well as Fst tell genetic distances, not the genome structure, giving often a false image of our ancestry.  In spite of weaknesses of admixture analyses in case of really old ancient samples (where no one can really figure the admixture history), in this particular case all samples are only 1000 years old and the link between them and us is significant and the admixture history figurable.  Good admixture results only call for two condition to be true:  at first the admixture history must be real and references must be right.  In many cases these conditions are not fulfilled and people after seeing senselessness start to bark up the wrong tree.           

grt036

East_Scandinavian 24.7
Slavic 18.8
Mediterranean 14.3
Northeast_European 14.0
Central_European 11.0
Northwest_European 8.8
Saami 4.4
Baltic 3.3

grt035

Northwest_European 40.8
Central_European 16.7
Mediterranean 14.8
East_Scandinavian 10.8
Saami 9.8
Baltic 5.7
Slavic 1.3

kal006 (this looks like present-day Estonians)

Baltic 54.3
Finnic 20.4
East_Scandinavian 12.8
Northeast_European 9.5
Siberian 2.0

stg021 (this looks like preset-day Swedes)

East_Scandinavian 43.5
Northwest_European 22.9
Mediterranean 12.8
Slavic 6.6
Saami 6.1
Northeast_European 2.5
Uralic 1.3
East_Asian 1.8
Baltic 1.7

84001 (this must be mainly British)

Northwest_European 64.2
Baltic 14.1
Uralic 5.0
Saami 4.7
East_Scandinavian 4.3
Slavic 2.1
Mediterranean 2.3
Finnic 2.8

84005 (a quarter Finn, maybe even more Finnish taking into account the Finnish demographic history after the Viking Age)

East_Scandinavian 39.6
Finnic 24.7
Baltic 13.6
Northwest_European 11.8
Slavic 3.1
Mediterranean 3.0
Central_European 3.6

For a comparison, a project sample of Finnish ancestry from Southwestern Finland:

Finnic 49.1
Northwest_European 25.1
East_Scandinavian 12.9
Northeast_European 5.1
Slavic 2.4
Saami 2.9
Baltic 2.3


urm160

Central_European 33.1
East_Scandinavian 29.9
Slavic 19.1
Finnic 6.8
Baltic 4.5
Uralic 2.9
Saami 1.8
Northwest_European 1.3


It is notable that many Viking Age Swedish samples show Saami without Finnish ancestry.  This probably means that the Finnish-Saami mixing was not yet as significant as today.  It is also possible that the Saami admixture here means common Swedish-Saami ancestry which is not clearly assignable using modern Saami references.