Of bone and ivory: Eastern Atlantic sources of the medieval European walrus ivory trade discovered by ancient mitochondrial and nuclear DNA

Ancient DNA analysis has revealed that European walrus ivory during the medieval period originated from both the western and eastern Atlantic regions, contradicting previous assumptions that all ivory came from Greenland. Researchers found that mitochondrial DNA analysis alone was insufficient to determine the true source of the ivory.

By examining workshop offcuts from an archaeological site in Sigtuna, Sweden, they were able to compare the geographical origins of the ivory with previously studied rostra, or pairs of attached tusks. They discovered that the genetic makeup of Atlantic walrus populations differed significantly between the west and east. Their low-coverage sequence data classified rostrums and tusks as either western or eastern Atlantic origin, overcoming limitations of using mitochondrial DNA alone.

The analysis showed that all medieval walrus rostra came exclusively from the western Atlantic, while half of the ivory specimens from Sigtuna were traced back to eastern Atlantic sources, including Iceland and the Barents Sea region. Importantly, the objects of eastern origin predate those from Norse Greenland, suggesting that the Barents Sea region was a more significant source of walrus ivory in medieval Europe than previously believed. This discovery highlights a broader extent and impact of medieval Arctic ecological globalization.