Thursday 14 September 2017

Swedish Viking Warrior burial shown to be female.

Birka was a settlement in central Sweden inhabited between the late eighth and late tenth centuries, with a population of between 700 and 1000, and trading links reaching as far as Central Asia and the Byzantine Empire. This site has been extensively explored by archaeologists since the late nineteenth century, with over 3000 burials located and over 1100 excavated. These have shown an urban society with three distinct classes, artisans, traders and warriors. One of the more notable burials at this site is Bj 581, a complete skeleton buried along with two horses, a sword, an axe, a spear, armour-piercing arrows, a battle knife, two shields, and other equipment, including a gaming set. This burial was first excavated in the nineteenth century, and was interpreted as a high ranking, male, Viking warrior. However from the 1970s onwards a number of archaeologists have looked at the bones of Bj 581 and suggested that the skeleton may in fact be female. This suggestion has proved to be somewhat controversial, as it does not fit in with our traditional image of a male-dominated Viking warrior society, despite the fact that numerous female warriors are recorded in the viking sagas (historical poems).

In a paper published in the American Journal of Physical Anthropology on 8 September 2017, Charlotte Hedenstierna-Jonson of the Archaeological Research Laboratory at Stockholm University, and the Department of Archaeology and Ancient History at Uppsala University, Anna Kjellström of the Archaeological Research Laboratory and Osteoarchaeological Research Laboratory at Stockholm University, Torun Zachrisson, Maja Krzewi nska, and Veronica Sobrado, also of the Archaeological Research Laboratory at Stockholm University, Neil Price, also of the Department of Archaeology and Ancient History at Uppsala University, Torsten Günther, and Mattias Jakobsson, of the Department Organismal Biology and Sci Life Lab at the Evolutionary Biology Centre in Uppsala University, Anders Götherström, again of the Archaeological Research Laboratory at Stockholm University, and Jan Storå, again of the Osteoarchaeological Research Laboratory at Stockholm University, describe the results of a new analysis of burrial Bj 581, using genetic analysis to determine the sex and ethnic origin of the skeleton, and strontium isotope analysis to attempt to uncover its geographical origin.

Hedenstierna-Jonson et al. were able to extract DNA from the left canine and left humerus of skeleton Bj 581. This was compared to three different DNA databases, the Human Origins dataset, the Swedish reference dataset, and the Population Reference Sample. This was combined with a fresh anthropological examination of the remains, to examine the validity of claims the skeleton appeared female.

Illustration by Evald Hansen based on the original plan of grave Bj 581 by excavator Hjalmar Stolpe; published in 1889. Hedenstierna-Jonson et al. (2017).

They also took samples from three of the molar teeth of Bj 581 and five other Birka individuals for strontium isotope analysis. Strontium isotopes in water vary with local geology, and are incorporated in tooth and bone, providing a record of where people have lived. Strontium isotope levels in tooth enamel become fixed at about puberty, reflecting the isotopic content of the water consumed at this time, unlike bone where the isotope content varies with water consumed throughout the life of the individual, and are often used not just in archaeology but in the identification of modern remains by forensic scientists, in those working with war graves and similar sites. 

Both the genetic and morphological analysis strongly support the idea that Bj 581 is female. The DNA analysis did not find a Y chromosome (indicative of maleness) and the skeleton showed a number of features associated with being female, such as a broad greater sciatic notch on the hip-bone, a wide preauricular sulcus, and the absence of a projecting mental eminence on the mandible. Combining this with a tooth-wear analysis to determine the age strongly suggests that individual Bj 581 was female and at least 30 years of age.

Strontium isotope analysis of the tooth enamel could not link the remains to any specific origin, but it could rule out an origin in central Sweden. Comparison of the DNA of Bj 581 suggested that it was most closely related to modern individuals from Britain, Iceland, the Orkney Islands, and Scandinavia, and to a lesser extent the eastern Baltic. This is broadly consistent with belonging to a high ranking Viking warrior class, known to have been an extremely mobile group.

The high quality and militaristic grave goods buried with skeleton Bj 581 strongly suggest a senior military rank, particularly the horses (valuable) and gaming set (indicative of an understanding of tactics). This is combined with a genetic ans strontium isotope analysis, which suggests an individual from outside the area but within the greater Viking world, also suggestive of a high rank. Hedenstierna-Jonson et al. do note that the skeleton of Bj 581 shows no signs of any battlefield injuries, which could be taken as direct evidence of a warrior occupation, but note that these are actually very rare in formal Viking burials, both at Birka and elsewhere, with almost all Viking skeletons with such injuries being known from mass graves at battle-sites, and therefore no inference can be made from the absence of such injuries on Bj 581.

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