Researchers have identified two ancient wolves on the Swedish island of Stora Karlsö, where the animals could not have arrived without human assistance. The remains, found in Stora Förvar cave, date to roughly 3,000–5,000 years ago and suggest that prehistoric people may have maintained close relationships with wolves before the emergence of fully domesticated dogs.
The study was conducted by scientists from the Francis Crick Institute, Stockholm University, the University of Aberdeen and the University of East Anglia. Their findings were published in Proceedings of the National Academy of Sciences, according to ScienceDaily’s report on the research.
Stora Karlsö covers about 2.5 square kilometers and has no native terrestrial mammals. Because wolves could not naturally cross the surrounding open water and establish themselves there, the researchers conclude that people must have transported them, likely by boat. The cave was used extensively by seal hunters and fishers during the Neolithic and Bronze Ages.
Genetic analysis showed that both specimens were wolves rather than dogs, with no evidence of dog ancestry. Isotope analysis indicated that the animals consumed substantial amounts of marine protein, including seals and fish. Their diet closely resembled that of the people living on the island, which researchers say may indicate that humans fed them.
The wolves were also smaller than typical mainland wolves. One individual had exceptionally low genetic diversity, a pattern that can occur in isolated or bottlenecked populations and may also be associated with domestication or selective breeding. The researchers caution, however, that natural causes cannot be ruled out.
Skeletal evidence provides another possible indication of human care. One Bronze Age wolf had severe damage to a limb bone that would probably have impaired its ability to move and hunt. Its survival long enough for the injury to leave a visible mark may suggest that it received some care or lived in conditions where it did not need to hunt large prey.
The evidence does not establish whether the wolves were tame, held in captivity or selectively bred. Instead, the researchers argue that the findings point to a range of human-wolf relationships that does not fit a simple progression from wild wolves to dogs. Some prehistoric communities may have managed or cared for wolves without fully domesticating them.
