Mapping people of the past by means of their bones

What is the best way to find out about a human being or animal that has been dead for perhaps several centuries? “Study the bones” is what Sabine Sten, professor of osteoarchaeology, would say. They can reveal an individual's age, body length, DNA, lifestyle, diseases, diet and location in the last years of life.

“Look at the bones in the fingers. Do you see the longitudinally marked edges of the bone? That shows this individual has worked a lot with his hands,” Sten says.

She points to a finger bone on a stocky skeleton from the Viking Age, laid out on a worktable in the Osteological Laboratory on Campus Gotland. It is that of a man, tall and with muscular legs. There are no visible injuries, old fractures or indications that he suffered from, for example, periostitis, but the spine shows clear signs of osteoarthrosis. His age at death was 35–45.

Before 1975, when Sten embarked on her career as an osteologist, this was more or less all the information that could be obtained from a skeleton. Since then, her research field has undergone massive development. Nowadays, procedures using technical equipment from specialist healthcare, such as computed tomography (CT), and analytical methods from the natural sciences including gene sequencing, are used.

Isotope analysis is one of the most important methods today for obtaining information on how a person lived. Briefly, this is about comparing the relationship among different variants of elements contained in the bones. Since their composition varies from one place to another and among foods, the isotopes can reveal whether people died in the same place where they were born, and whether their diet was mainly plant-based or composed largely of meat or fish. Whether the meat a person consumed came from herbivores or carnivores and whether the fish was caught in the sea or lakes are also discernible.

In a new research project, Sten is now planning excavations on Gotska Sandön to find out which people have inhabited the island and dwelt here through the ages. The exposed location in the middle of the Baltic Sea, where the winds and waves that constantly surround the island, threaten the archaeological treasures in the ground.

“The island is moving slightly. It’s noticeable on some high-level burial mounds where the sand is shifting. Graves are getting closer to the shoreline and graves have disappeared,” Sten explains.

This makes it a race against time to find and document the skeletal parts that the erosion exposes at ground level.

Analysis of human remains involves scientists in several different disciplines. A well-known example of this was when, at Uppsala Cathedral in 2014, Sabine Sten supervised the reopening of a reliquary containing the remains of King Eric IX (“Eric the Holy”) and associated relics. This Swedish king perished in battle in 1160, and one question the researchers were keen to answer was whether any evidence could be found for the “Legend of Eric”, written a century after his death. This portrayed him as not only a good Christian but a saint.

“We spent two days analysing the bones. On the first day, we carried out a basic examination in which we determined sex, age and body length, and whether injuries had occurred. We also took samples for DNA analysis. On the second day, we received help from Uppsala University Hospital, with CT and an osteoporosis examination to see whether he had brittle bones. The isotope analyses showed that his diet was heavily dependent on lake fish. The skeleton was very largely undamaged, but he’d suffered an injury to the forehead that had healed well. Compared with today’s men in their 40s, his bones were in good condition. By moving a lot, he’d loaded his bones, increasing their density,” Sten says.

At least in part, the saint’s legend of therefore seems to tally with reality. Since there were no restrictions on eating fish during Lent, the dominance of fish in Eric the Holy’s diet may be explained by the fact that he complied with the Lent rulings of the Church, and may thus be regarded as a good Christian. In addition, the injuries to the cervical vertebra show that he probably died by beheading, just as the legend tells.

Eric was not the first Swedish king who captured Sabine Sten’s interest in her research. She also participated in the quest for Magnus Ladulås in Riddarholm Church, Stockholm.

Having died in 1290, he was buried there; but when his grave monument was opened in 2011, it turned out that he was not inside. The adjacent tomb, where King Karl Knutsson lay at rest, was also examined.

“The dating indicates that Karl Knutsson Bonde is the one who’s lying there,” Sten says.

Conceptual worlds being overturned by research findings is something she has experienced before, not least when she was studying animal bones.

“We analysed DNA from hedgehogs to find out where the ones on Gotland come from. They weren’t here originally, so they must have been brought here across the sea by people in the Stone Age. The DNA showed that they originated from western Sweden, and this shows early contact with the Swedish mainland.”

Åsa Malmberg