Scientists find that humans and dogs have such a friendly relationship because early ancestors fed salmon to canines 12,000 years ago
Early humans in Alaska were sharing their salmon catches with ancient canines 12,000 years ago. This shows that close relationships between humans and dog ancestors developed 2,000 years earlier than anyone previously thought in the Americas.The findings, published in the journal Science Advances, challenge long-held ideas about how and when wolves turned into tame companions. By studying chemical clues called stable carbon and nitrogen isotopes in fossilized bones, scientists discovered a diet packed with fish. This diet suggests these ancient animals were living right next to human camps and eating shared food instead of hunting completely on their own in the wild.
The discovery at Swan Point
Archaeologists working at the Swan Point dig site, located about 70 miles southeast of Fairbanks, Alaska, found an adult canine lower leg bone dating back 12,000 years. A later discovery in 2023 at the nearby Hollembaek Hill site revealed an 8,100-year-old canine jawbone.These finds allowed researchers to build a complete history of large canines in interior Alaska. They put together a database of 76 ancient and 35 modern specimens, including wolves, coyotes, and dogs. While most of these historical animals lived on land-based prey, the bones from Swan Point and Hollembaek Hill showed chemical proofs of a diet heavy in salmon.Ben Potter, an archaeologist at the University of Alaska Fairbanks and co-author of the study, noted that wild canines rarely hunt salmon on their own. In a public statement, Potter said: “[The high salmon diet] is the smoking gun, because [canines are] not really going after salmon in the wild.”
The 8,100-year-old jawbone suggests humans living in interior Alaska were feeding salmon to canines (Credits: Zach Smith)
Did the first human travelers bring tamed dogs to the Americas?
Genetic testing showed that these salmon-eating canines are not the direct ancestors of modern pet dogs. However, their eating habits prove that they filled a very similar social and partnership role long before today’s breeds existed.The timeline for the first humans arriving in the Americas is estimated to be between 27,000 and 16,000 years ago. Scientists are still trying to figure out whether those first human travelers brought tame dogs across the Bering land bridge or befriended local wild wolves when they arrived. This new evidence points to a slow, twisting process rather than a single event where wolves suddenly became dogs.François Lanoë, an archaeologist at the University of Arizona and co-author of the study, explained that human-canine interactions were much more flexible than old theories suggest. Lanoë told Gizmodo’s Isaac Schultz: “The general assumption has been that domestication happened once and clearly separated canids that interact with people (dogs) from those who don’t (wolves). Our study instead shows that canid-people relationships were complex, continue to be today, and involve more than domestication, but also things like taming of wild wolves and commensality (wolves hanging around human settlements).”This point of view is not accepted by everyone in the scientific community. Some researchers suggest that the canines could have picked up salmon leftovers near rivers on their own during big fish runs, without any direct help from humans.Mikkel Sinding, a biologist at the University of Copenhagen who was not involved in the research, told the Washington Post’s Carolyn Y. Johnson: “There are several possible explanations. Yes, humans could have fed it, but it could also just naturally have had this diet.”
How the research team collaborated with the tribal members of Alaska
The research team worked closely with local Indigenous communities in Alaska’s Tanana Valley to get permission for the genetic testing, which requires destroying small pieces of the bones. The Healy Lake Village Council, representing the Mendas Cha’ag people, gave the green light for the analysis.Today, tribal members have strong bonds with working sled dogs and house pets. The archaeological evidence suggests these connections go all the way back to the very first settlements in the region.Evelynn 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 love that we can look at the record and see that thousands of years ago, we still had our companions.”
The ‘puppy-dog eyes’
While archaeologists are finding out how early these relationships started, experts who study body structures are rethinking how dogs developed the physical traits they use to talk to us. New research into wild canine anatomy 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 savanna. The research showed that these wild animals have the exact same well-developed eye muscles that pet dogs use to make that sad, pleading look known as “puppy-dog eyes.”This finding complicates older theories about dog evolution. A 2019 study comparing wolves and domestic dogs noted that pet dogs had much stronger eyebrow muscles and made intense facial movements that wolves could not match. That study suggested humans specifically chose and bred dogs with highly expressive eyes during history. Follow-up research in 2022 confirmed that pet dogs have a higher amount of fast-twitch muscle fibers in their faces compared to wolves, making their faces move a lot like human faces.
African wild dogs might use facial expressions to communicate with each other as they hunt in packs on the savanna
Communication on the savanna
The dissection of an adult male African wild dog that passed away at the Phoenix Zoo proved that these facial muscles are fully present without any history of living with humans.Heather Smith, an anatomist at Midwestern University and lead author of the muscle study, explained that finding these traits in wild species changes our view of why they grew in the first place. Smith told Live Science’s Joanna Thompson: [The discovery] “kind of debunks the idea that domestic dogs are the only canids that have this, and that they 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 the open savanna, where it is easy to see a pack mate’s face. On the other hand, wolves usually hunt in thick forests full of rocks and trees, where making sounds like howling or leaving scent marks works much better. This means that wolves might have simply lost these specific eye muscles over time as their home environment shifted, rather than pet dogs developing them just to please humans.Future studies will expand to look at the facial muscles of other wild canine species, like foxes and Asian wolves, to see just how common these expressive traits are across the bigger, more expansive canine family tree.
