Study: Humans fed salmon to their canines 12,000 years ago, suggesting the origin of our relationship with dogs
Early humans in Alaska shared salmon catches with ancient canines 12,000 years ago. This shows that close relationships between humans and canine ancestors evolved 2,000 years earlier than anyone had previously thought in the Americas.The findings, published in the journal Science Advances, challenge long-held ideas about how and when wolves became tame companions. By studying chemical evidence called stable carbon and nitrogen isotopes in fossilized bones, scientists discovered a diet full of fish. This diet suggests that these ancient animals lived next to human camps and ate in common rather than hunting alone in the wild.
Discovery at Swan Point
Archaeologists working at the Swan Point excavation site, located about 70 miles southeast of Fairbanks, Alaska, found a lower leg bone of an adult dog dating back 12,000 years. A subsequent discovery in 2023 at the nearby Hollembaek Hill site revealed an 8,100-year-old dog jawbone.These discoveries have allowed researchers to build a complete history of large canines in interior Alaska. They compiled a database of 76 ancient and 35 modern specimens, including wolves, coyotes and dogs.
While most of these historical animals subsisted on land-based prey, bones from Swan Point and Holembic Hill showed chemical evidence of a diet rich in salmon.Wild canines rarely catch salmon on their own, noted Ben Potter, an archaeologist at the University of Alaska Fairbanks and co-author of the study. Potter said in a public statement:[The high salmon diet] It’s a smoking gun, because [canines are] I don’t really go after salmon in the wild.
An 8,100-year-old jawbone suggests that humans living in the interior of Alaska fed salmon to their tusks (Credit: Zach Smith)
Did early human travelers bring tame dogs to the Americas?
Genetic tests have shown that these salmon-eating canines are not direct ancestors of modern domestic dogs. However, their eating habits prove that they played a very similar social and partnering role long before current subspecies existed.The timeline for the arrival of the first humans in the Americas is estimated to be between 27,000 and 16,000 years ago. Scientists are still trying to figure out whether these early human travelers brought tame dogs across the Bering Land Bridge or befriended local wild wolves upon their arrival.
This new evidence points to a slow, twisting process rather than a single event where wolves suddenly turned into dogs.François Lannoy, an archaeologist at the University of Arizona and co-author of the study, explained that interactions between humans and dogs were much more fluid than ancient theories suggest. Lanois told Gizmodo’s Isaac Schultz: “The general assumption was that domestication occurred once and dogs that interacted with people (dogs) were clearly separated from those that did not interact with people (wolves).” Instead, our study shows that dog-dog relationships were complex, and remain so today, and involved more than just domestication, but also things like domestication of wild wolves and cohabitation (wolves loitering around human settlements).This point of view is not accepted by everyone in the scientific community. Some researchers suggest that the tusks could have picked up salmon remains near rivers on their own as larger fish escaped, without any direct help from humans.“There are many possible explanations,” Mikkel Sinding, a biologist at the University of Copenhagen who was not involved in the research, told The Washington Post’s Caroline Johnson. “Yes, it could have been fed by humans, but it is also possible that it had this diet naturally.”
How the research team collaborated with tribal members in Alaska
The research team worked closely with local indigenous communities in Alaska’s Tanana Valley to obtain permission to conduct genetic testing, which requires destroying small pieces of bone.
The Healy Lake Village Council, which represents the Mindas Chag people, gave the go-ahead for the analysis.Today, tribal members have strong bonds with working sled dogs and household pets. Archaeological evidence suggests that these links date back to the first settlements in the area.Evelyn Combs, an archaeologist and member of the Healy Lake Tribe, shared the personal meaning of the discovery in a statement released with the study: “I really like that we can look at the record and see that thousands of years ago, we still had our companions.”
“puppy dog eyes”
As archaeologists discover how early these relationships began, experts who study body structures are rethinking how dogs developed the physical traits they use to talk to us. New research into the anatomy of wild dogs has found that some features we thought came from human breeding actually exist in completely wild animals.A study published in The Anatomical Record looked closely at the facial structure of the African wild dog (Lycaon pictus), a highly social animal that hunts in packs on the African savannah.
Research has shown that these wild animals have the same well-developed eye muscles that domestic dogs use to form that sad, pleading look known as “puppy dog eyes.”This discovery complicates long-standing theories about dog evolution. A 2019 study comparing wolves and domestic dogs indicated that domestic dogs have much stronger brow muscles and make intense facial movements that wolves cannot match. That study suggested that humans specifically selected and bred dogs with highly expressive eyes throughout history.
Follow-up research in 2022 confirmed that domestic dogs have a greater amount of fast-twitch muscle fibers in their faces than wolves, making their faces move much like human faces.
African wild dogs may use facial expressions to communicate with each other while hunting in groups on the savannah
Communications in the Savannah
An autopsy of an adult male African wild dog that passed away at the Phoenix Zoo demonstrated that these facial muscles were present entirely without any history of living with humans.Finding these traits in wild species changes our view of why they grow in the first place, explained Heather Smith, an anatomist at Midwestern University and lead author of the muscle study. Smith told Live Science’s Joanna Thompson: [The discovery] “It kind of debunks the idea that pet dogs are the only dogs that have this, and that it evolved specifically for us.”Researchers suggest that African wild dogs use these advanced eye muscles to send silent visual signals to each other while hunting across open savannas, where the face of a pack mate is easier to see. On the other hand, wolves usually hunt in dense forests filled with rocks and trees, where making sounds like howling or leaving scent marks is much better. This means that wolves may have simply lost these specific eye muscles over time as their home environment changed, rather than domestic dogs developing them just to please humans.Future studies will expand to look at the facial muscles of other wild dog species, such as Asian foxes and wolves, to see how common these expressive traits are across the larger, more extensive canine family tree.