Kjellström was a co-author on the 2017 paper. Her osteological assessment was the bridge between the longstanding question about the grave’s occupant and the decision to pursue genomic testing. The paper’s significance rests, in part, on the convergence of two different lines of evidence — the morphological and the genetic — both pointing to female biological sex. If only the DNA had suggested female sex, or only the morphology, the finding would have been more ambiguous. The convergence strengthened the conclusion considerably.
The decision to extract DNA from a left canine tooth and a left humerus (upper arm bone) reflected both the availability of those elements in the Bj 581 assemblage and the practical requirements of ancient DNA work. Teeth are often well-preserved because the enamel protects the inner pulp, which can retain DNA over centuries or millennia. Dense cortical bone from long bones, like the humerus, is also a reliable source under good preservation conditions. The specific choice of elements is a detail that matters for assessing the study’s quality: these are not second-best choices, but among the most reliable sources for ancient DNA under typical burial conditions.
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## Strontium Isotopes: The Geography Written in Her Teeth
Beyond the chromosomal finding, the 2017 study produced a second major analytical result that has received less attention in popular coverage but adds significantly to the picture of the individual.
Strontium isotope analysis works because the ratio of strontium-87 to strontium-86 in the environment varies by geology. When you eat and drink, the strontium in your food reflects the local geology — the rocks, soils, and water of the place where your food was produced. This strontium becomes incorporated into your bones and teeth as they form. Tooth enamel, once formed, does not remodel the way bone does, so the strontium ratio in your teeth is a permanent record of the geological environment where you grew up.