Researchers have uncovered ancient wolf remains on a small, isolated island in the Baltic Sea, a location the animals could not have reached without human help. The findings point to a surprising possibility that prehistoric people deliberately brought grey wolves to the island and may have kept or managed them. The research was published in Proceedings of the National Academy of Sciences and led by scientists from the Francis Crick Institute, Stockholm University, the University of Aberdeen, and the University of East Anglia.

The remains, dated to between 3,000 and 5,000 years old, were discovered in the Stora Förvar cave on the Swedish island of Stora Karlsö. Archaeological evidence shows the site was heavily used by seal hunters and fishers during the Neolithic and Bronze Ages. Covering just 2.5 square kilometres, the island has no native land mammals, which means any wolves found there must have been transported by people.

Genetic Evidence Confirms They Were Wolves

DNA analysis of two canid bones confirmed the animals were wolves rather than early dogs, with no signs of dog ancestry. Despite this, several features suggested close contact with humans. Chemical analysis of the bones showed the wolves ate large amounts of marine food, including seals and fish, matching the human diet on the island and indicating they were likely fed by people. The wolves were also smaller than typical mainland wolves, and one showed unusually low genetic diversity, often seen in isolated populations or those shaped by human control.

"The discovery of these wolves on a remote island is completely unexpected," said Dr. Linus Girdland-Flink of the University of Aberdeen, a lead author of the study. "Not only did they have ancestry indistinguishable from other Eurasian wolves, but they seemed to be living alongside humans, eating their food, and in a place they could have only have reached by boat. This paints a complex picture of the relationship between humans and wolves in the past."

Rethinking Domestication and Wolf History

The presence of wolves in a human settlement challenges traditional views of how people and wolves interacted in the past and how dogs eventually emerged. Researchers cannot yet say whether these wolves were tame, kept in captivity, or managed in another way. However, their long-term presence on an isolated island suggests intentional and ongoing human involvement.

"It was a complete surprise to see that it was a wolf and not a dog," said Pontus Skoglund of the Ancient Genomics Laboratory at the Francis Crick Institute and senior author. "This is a provocative case that raises the possibility that in certain environments, humans were able to keep wolves in their settlements, and found value in doing so."

Genetic Clues and Possible Human Care

Anders Bergström of the University of East Anglia and co-lead author, commented: "The genetic data is fascinating. We found that the wolf with the most complete genome had low genetic diversity, lower than any other ancient wolf we've seen. This is similar to what you see in isolated or bottlenecked populations, or in domesticated organisms. While we can't rule out that these wolves had low genetic diversity for natural reasons, it suggests that humans were interacting with and managing wolves in ways we hadn't previously considered."