Ancient island wolves point to closer ties with prehistoric people

Ancient wolf remains found on a small Swedish island are prompting researchers to reassess how prehistoric people lived with wolves before and alongside dog domestication. Stockholm University said the animals, dated to roughly 3,000 to 5,000 years ago, were discovered on Stora Karlsö, an isolated Baltic island with no native land mammals.

The study, published in the Proceedings of the National Academy of Sciences, was conducted by researchers from the Francis Crick Institute, Stockholm University, the University of Aberdeen and the University of East Anglia. According to the research team, the wolves could not have arrived on the island without human help, meaning people likely brought them there by boat.

Finds from a cave used by hunters and fishers

The remains came from Stora Förvar cave, an archaeological site on Stora Karlsö linked to seal hunters and fishers during the Neolithic and Bronze Ages, Stockholm University said. The island is about 2.5 square kilometers, and researchers said its isolation makes natural colonization by wolves implausible.

The team studied two canids from the cave. Genetic analysis identified both as wolves, not dogs, and the researchers said they found no evidence that the animals had dog ancestry.

That distinction is central to the study’s argument. The animals were wolves by ancestry, yet several lines of evidence suggest they lived in close contact with people, according to the researchers.

Diet and DNA suggest human involvement

Isotope analysis showed the wolves ate substantial amounts of marine protein, including fish and seals, Stockholm University said. Researchers reported that this diet resembled that of the humans using the island, suggesting the animals were fed by people or had access to human food.

The wolves were also smaller than typical mainland wolves, according to the study. One of the animals had unusually low genetic diversity, a pattern that can appear in isolated populations, bottlenecks or domesticated organisms, the researchers said.

Anders Bergström of the University of East Anglia, a co-lead author, said the wolf with the most complete genome had lower genetic diversity than any other ancient wolf the team had examined. He said natural causes could not be ruled out, but the finding points to forms of human interaction and management that researchers had not previously considered.

Linus Girdland-Flink of the University of Aberdeen, a lead author of the study, called the island discovery unexpected. He said the animals had ancestry matching other Eurasian wolves while appearing to live near humans, eat human-associated food and occupy a place reachable only by boat.

A damaged bone raises questions about care

The study also described a Bronze Age wolf with severe damage to a limb bone. Researchers said the injury likely would have made movement and hunting difficult, yet the animal survived long enough for the condition to be visible in its skeleton.

According to the team, that survival may indicate the wolf received care or lived in conditions where it did not need to hunt large prey. The researchers said they cannot determine whether the wolves were tame, confined or managed in another way.

Pontus Skoglund of the Francis Crick Institute, the study’s senior author, said the identification of the animals as wolves rather than dogs was a surprise. He said the case raises the possibility that some prehistoric communities kept wolves in settlements and saw value in doing so.

Jan Storå, professor of osteoarchaeology at Stockholm University, said combining bone analysis and genetic data opened new views of Stone Age and Bronze Age relationships between humans and animals, including wolves and dogs. The researchers said the findings show that prehistoric human-wolf relationships may have been more varied than a straight path from wild wolves to domestic dogs.

This story draws on original reporting from ScienceDaily.