Science1 publisher2 min readPublished
Ancient DNA from 142 medieval Swedes finds close kin rare among people buried together
Stockholm University researchers analyzed DNA from 142 medieval Swedes and found close relatives were uncommon among people sharing a grave. The Science Advances study turns the parent-and-child reading of a shared grave into a hypothesis that needs testing.
The Scientist · Science desk
What happened
- The remains came from graves at Sigtuna near Stockholm, Västerhus in Jämtland and Fjälkinge in Skåne, and more than 60 belonged to children or adolescents.
- At Västerhus, where men and women were generally buried on different sides of the churchyard, DNA-sexed boys and girls followed the same split.
- DNA linked a woman the researchers call Lady 56 to her parents, her brother and two daughters, all buried in the Västerhus churchyard.
- Lady 56 was buried with a scallop shell, a widely recognized symbol of the medieval pilgrimage to Santiago de Compostela in Spain.
Compiled by The ScientistSomething wrong?How this is made
Why it matters
- constraint A shared grave holding an adult and a child is no longer enough, on its own, to support a parent-and-child reading in an excavation report.
- decision Anyone interpreting multi-person graves now has to choose between testing kinship genetically and reporting it as an untested assumption.
- capability Studies of sex-based burial custom can now include young children, whose skeletons alone could not be sexed reliably.
The finding rests on a comparison within each cemetery. Close relatives were scarce among people sharing a grave even at sites where the team found many family connections across the wider buried population [5]. That comparison deals with the dullest explanation. If relatives had turned up nowhere, a thin sample could account for the shared graves without kin. Kin were detectable in the same ground, so the shortfall lies in who was placed together.
Lead author Maja Krzewińska of Stockholm University's Centre for Palaeogenetics gave the finding as a proportion. "We often assume that adults and children sharing a grave were parents and children or other close family members. In most cases, that was not what we found," she said [4]. The release does not give the number of shared graves, the share that held any relative, or how distant a relationship the analysis could detect. As stated, the finding covers close relatives only [3].
Anna Kjellström, a researcher in the university's Department of Archaeology and Classical Studies, put the emphasis on method. "Archaeologists have debated the relationships between people buried together in this type of grave for a long time. Ancient DNA has finally given us the tool we have been waiting for to test these interpretations directly," she said [6]. The DNA cannot say why unrelated people were buried together. Genetics can exclude close kinship. The social, religious or community ties the authors suggest in its place are hypotheses the DNA cannot confirm [7].
Children and adolescents made up more than 42 percent of the sample [1]. DNA let the team sex those whose bones were too young to sex reliably [8]. What was measured is genetic sex and grave position. The researchers read the Västerhus placement pattern as a sign that gender identity was recognized early in life [10]. "The children were not treated as a separate category. In death, they appear to have been treated according to the same social and religious principles as adult men and women," said Anders Götherström, professor of molecular archaeology [11].
The Lady 56 case mixes two kinds of evidence. Her family ties are genetic [12]. The pilgrimage rests on a single object, the scallop shell, and the release says only that she may have made the journey to Santiago de Compostela [13]. She died before 30 [14]. The parents, brother and daughters she was genetically linked to were buried in different parts of the same cemetery [15].
What to watch
- The grave-by-grave counts in the Science Advances paper: how many burials held several people, and how many of those contained any detected relative.
- Whether other evidence from Lady 56's remains tests the pilgrimage that her scallop shell suggests.
- Kinship testing of shared graves at other Scandinavian cemeteries, to see whether the Sigtuna, Västerhus and Fjälkinge pattern holds elsewhere.