Prehistoric wolf remains found on a Baltic island suggest that humans cared for wolves thousands of years before dogs fully emerged, according to a new study.
Archaeologists found the remains, dated to 3,000-5,000 years ago, in the Stora Förvar cave on the Swedish island of Stora Karlsö. The cave showed signs of heavy use by seal hunters and fishers during the Stone Age and Bronze Age, researchers from Stockholm University said.
The island measures just 2.5sq km and there is no evidence of native land mammals. Because of this isolation, researchers believe the wolves were brought in by people, most likely on ships.
Dogs first emerged from wolves during the Old Stone Age, before other domesticated animals. But where and how many times domestication took place remains unclear.
One leading theory suggests that wolves gradually adapted to living near humans, while another proposes that people hand-reared wolf pups from a very early age. No dog remains dating to the earliest stages of domestication have yet been identified.
The new evidence showing wolves and humans living together on the Swedish island points to likely prehistoric domestication of wolves.
DNA analysis of two bones found in the cave confirmed the animals were wolves and not dogs, with several of their features suggesting the canines had close contact with humans.
One of the wolves seems to have survived with a limb injury, which would have made hunting difficult, hinting it was cared for.
“The discovery of these wolves on a remote island is completely unexpected,” Linus Girdland-Flink from the University of Aberdeen, an author of the study published in the journal PNAS, said.
“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 reached by boat.”
While it is unclear from the fossils whether the wolves were tamed, kept in captivity, or managed in another way, the findings indicate that the relationships between humans and wolves were far more varied than once thought.
The interactions between humans and wolves at the cave appear to have involved close cooperation, hinting at early experiments with domestication that didn’t lead directly to modern dogs, scientists say.
“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,” Anders Bergström, another study author from the University of East Anglia, said.
“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,” said study co-author Pontus Skoglund from the Francis Crick Institute.