Dogs were hanging around people a lot earlier than the genetic record had shown.
Two studies published in Nature on March 25 found that dogs were living alongside humans in western Eurasia about 14,000 to 16,000 years ago, before humans developed agriculture. The findings push back the earliest genetic evidence of a domesticated canine by about 5,000 years and add new detail to how dogs spread.
Modern dogs descended from ancient wolves, but researchers still do not know exactly when domestication began. A 2015 analysis using computer simulations of the canine family tree suggested the split happened around 27,000 to 40,000 years ago. Before the new papers, the oldest genetic evidence of a domesticated dog came from remains in northwestern Russia dated to nearly 11,000 years ago.
One of the new studies examined DNA from bones of more than 200 canines recovered from archaeological sites in Europe and southwestern Asia, including Turkey, Switzerland and Scotland. The analyses showed that some of the animals were dogs. The oldest was a Swiss animal, dated to 14,200 years ago, that lived with a hunter-gatherer group.
That Swiss dog shared ancestry with later dogs from other places, suggesting the animals descended from one population and that different human societies were acquiring dogs from each other.
“It is kind of the equivalent of a new blade or a new point or a new kind of material culture or art form or something, where everybody’s getting really excited about having this fun new thing around,” Greger Larson, a paleogeneticist at the University of Oxford in England and co-author of both studies, told Emily Anthes at the New York Times. “And it’s useful, and it’s interesting, and it’s probably cute.”
The second study found even older genetic evidence of a dog. Remains from a site in Turkey produced a 15,800-year-old domesticated animal. DNA analysis also identified ancient dogs at other sites in western Eurasia, including a 14,300-year-old individual in England.
The Turkish and English dogs lived nearly 2,000 miles apart, but they were still closely genetically related. The researchers said that this suggests dogs were already widespread across the region by then.
The studies also found signs that humans in different places treated dogs in similar ways. William Marsh, a paleogeneticist at the Natural History Museum in London and co-author of the study, told Ewen Callaway at Nature that the animals “were treated in very similar ways.”
Chemical analyses suggested that people at both sites fed their dogs the same food they ate. The English dog’s skull had decorative perforations like those found on human skulls. In Turkey, dogs were buried on top of deceased people.
The research also tracked what happened later, when the first farmers moved into Europe from southwestern Asia about 9,000 years ago. The studies found that these farmers brought dogs with them, which led to more animal trading.
Those farmers nearly fully replaced earlier human populations in Europe, but the research suggests they did not do the same with dogs. According to the studies, only about 50 percent of European dog DNA was replaced in later animals.
“They seem to incorporate these dogs rather than trying to replace them with their own,” Anders Bergström, a geneticist at the University of East Anglia in England who co-authored both papers, told David Grimm at Science.
The work supports the idea that all dogs came from one place, possibly somewhere in Asia, with additional interbreeding between early dogs and wolves. Adam Boyko, a geneticist at Cornell University who was not involved in the research, told Science News’ Tom Metcalfe, “Of course, we can’t rule out that some early fossils classified as wolves were actually tame and effectively dogs.” He added, “But from the standpoint of modern dogs, it seems they all share a single domestication origin.”
Researchers still do not know what roles dogs had in hunter-gatherer groups 14,000 years ago. Laurent Frantz, a paleogeneticist at Ludwig Maximilian University of Munich in Germany who worked on both studies, told the Times that it is possible the animals did different jobs in different human societies.
Beth Shapiro, an evolutionary biologist at the University of California, Santa Cruz, who was not involved in the work, told Science News the studies were a “significant advance” in understanding the origins of dogs.
