Researchers have discovered evidence that humans exercised some control over wolves on a remote island in the Baltic Sea 3,000 years ago. The bone samples they examined as part of a study published on the 24th in the journal PNAS suggest the possibility that the animals were taken there by humans.
The canid bones, dated to between 3,000 and 5,000 years ago, were found in a cave on the island of Stora Karlsö. It is five kilometers from a larger island, Gotland, and 80 kilometers from the Swedish mainland.
The cave, called Stora Förvar, was excavated between 1888 and 1893, revealing rich archaeological material, including cranial and postcranial bones of canids.
With advances in methodology and techniques for working with ancient DNA and the availability of databases, researchers sequenced the bones’ genes to check whether they came from dogs, wolves, or hybrid animals. They concluded that the genes of two individuals were closest to the DNA of a 5,100,000-year-old wolf found in Scandinavia.
Some evidence suggests that wolves were brought to the island of Stora Karlsö by humans, due to the lack of local terrestrial species. Gotland and Stora Karlsö have never been connected to the Scandinavian continent. The mammalian fauna of the larger island appears to have been introduced by humans, including hares, foxes, wild pigs and hedgehogs.
According to one of the study’s authors, Linus Girdland Flink, professor at the School of Geosciences at the University of Aberdeen, UK, the relationship with wolves on the island of Stora Karlsö is unexpected and different from that humans have with domestic dogs.
“Although it is very difficult to discern the exact nature and purpose of this relationship, it (the document) suggests that these wolves were neither entirely wild nor entirely domesticated, but perhaps something in between,” he explains.
It is not yet possible to know what functions wolves have for humans on the island. Flink says the next step in research is to find out how common this type of relationship was and whether it was something rare or a common practice in prehistory. This involves the systematic search for genetic and archaeological evidence of this relationship in Scandinavia and other regions.
Findings raise questions about domestication
Flink says he was surprised to discover that the dog genes actually belonged to individuals considered 100 percent genetically wolf. He says that when a researcher finds canine remains, the first assumption is that the material belongs to dogs and, if they are wolves, that they were hunted in the wild. What they found, however, does not match these alternatives.
“Our findings force us to rethink the history of domestication by showing that some early human communities had a much more complex and intimate relationship with wild wolves than we previously imagined,” he says.
For Professor Tiago Pedro Ferreira Tomé, from the Department of Anthropology and Archeology of the UFMG (Federal University of Minas Gerais), the article provides an interesting and well-founded discussion. The professor, who was not involved in the research, believes the study indicates the existence of a “prolonged and deliberate” interaction between humans and wolves.
The canids in question are smaller than modern wolves in Scandinavia. Reducing the size of domestic animals is associated with their integration into a human-created structure to protect them, which reduces the need for large sizes, according to the UFMG professor.
By looking at the genes present in the bones, scientists were able to notice that they came from a population without much genetic diversity, which could signal a scenario of reproductive control in a small population of wolves.
The researchers also analyzed the isotopes present in the bones and noted that the canines maintained a diet rich in marine proteins, like fish. Access to this type of food suggests a reliance on humans, as capturing marine protein can be a challenge for wolves and dogs.
The diet of wolves, combined with evidence that local economic activity was based on the sea, may indicate that animals were somehow linked to marine resources, Flink adds.
Tomé says the study reveals a possible interaction between wolves and humans in a broader context of animal domestication. Some of the oldest archaeological evidence of domestic dogs dates back 17,000 years.
This means that “at the same time that in many parts of the world we already had many human groups living with domesticated dogs for millennia, this specific group apparently lived with wolves.”
He points out that wolves possess certain characteristics that may have facilitated this relationship, such as sociability, the ability to establish relatively complex social structures, as well as the propensity to cooperate with each other within a group. “Did this somehow facilitate this cooperation with human beings? We have no way of knowing, but it’s something we have to consider,” he says.
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