Scientists—and plenty of doting dog owners—have long wondered when and where wolves began their evolution to become humanity’s best friend.
And though they haven’t fully solved it, researchers have now added a big, new piece to the dog domestication puzzle. Today’s modern dogs may have descended from two separate populations of ancient wolves: one in eastern Asia and another in the Middle East, according to a new paper published this week in Nature.
While two distinct domestication events are possible, another explanation is that dogs were domesticated in one location, then later bred with wolves elsewhere, intermixing their DNA.
“We can’t tell [the two different] scenarios apart,” says Anders Bergström, an evolutionary genomicist at the Francis Crick Institute and an author of the study, to the New York Times‘ Emily Anthes. “But we can say that there were at least two source populations of wolves.”
Researchers generally agree that modern-day dogs evolved from gray wolves (Canis lupus) at least 15,000 years ago, during the last Ice Age. But nearly everything else about the domestication of dogs is a mystery, including when, where and with what group of humans wolves began to evolve into dogs. Past research has concluded that dogs may have been first domesticated in Asia, Europe, the Middle East or, possibly, in multiple locations.
This new paper doesn’t pinpoint the exact location of dog domestication, but it does offer some important insights into wolf genetics. More than 80 researchers from 16 countries joined together for this research, which involved sequencing the genomes of 66 ancient wolves and analyzing six additional previously sequenced genomes from archival remains. The wolves analyzed in this study lived in Europe, Siberia and North America over the last 100,000 years.
With the sequenced genomes in hand, the researchers used computer software to compare and contrast the 72 animals with the genome of today’s dogs, creating an ancient genetic family tree.
As a whole, the research creates a much more “detailed picture of wolf ancestry, including around the time of dog origins,” Bergström says in a statement, which will undoubtedly help scientists get one step closer to figuring out exactly when and where dogs were domesticated.
“Having this many ancient wolf genomes is a huge advance in the field,” Adam Boyko, a canine geneticist at Cornell University who was not involved in the study, tells the New York Times. “I’m sure other researchers are going to love to get their hands on it and explore some of their own pet theories.”
Despite the diversity of wolf DNA, the researchers didn’t find a singular ancient wolf that is directly related to all modern dogs. But they did learn that dogs are more genetically similar to ancient wolves in Asia than wolves in Europe, which builds on previous research that suggests dogs likely originated somewhere in Asia.
The samples “help narrow down the place of origin,” says Yohey Terai, an evolutionary biologist at Japan’s Graduate University for Advanced Studies who was not involved in this paper, to Science‘s Michael Price.
To more directly link dogs with an ancient wolf population, researchers simply need more specimens from all around the world, particularly from samples from the southern hemisphere. But that’s challenging because DNA is best preserved in colder climates, hence the more abundant samples from the northern hemisphere used in this study.
“There are still big parts of the map where we don’t have many samples,” Bergström tells the New Scientist‘s Jason Arunn Murugesu.
The scientists were also surprised to learn how genetically connected the various wolf populations remained over tens of thousands of years around the world, which suggests the canines likely traveled and mated periodically. That may have allowed wolves to survive the end of the Ice Age, while many other mammals went extinct, per the New York Times.
In addition, the study answered a question that had been perplexing researchers since archaeologists uncovered an 18,000-year-old pup in Siberia in 2019: Was it a wolf or a dog? After studying its genetics, the scientists determined it was a wolf.