The relationship between dogs and humans is a special one: After all, they were the first animals that humans managed to domesticate. But while dogs may be man’s best friend, scientists are still divided on just where they came from. Now, a new genomic study published in the Proceedings of the National Academy of Sciences suggests that dogs first became Canis familiaris somewhere in modern-day Mongolia and Nepal.
The origins of the domesticated dog are extremely muddled, in part because they accompanied humans, who trekked around the globe for tens of thousands of years. While scientists are fairly certain that dogs originally evolved from grey wolves, the candidates for their birthplace are all over the map. Past studies pointed towards parts of Siberia, South China and Europe, just to name a few.
So what makes Cornell University’s Adam Boyko so sure they came from Central Asia?
For starters, he and his team collected DNA samples not just from purebred poodles, but from the common stray mutts known as “village dogs” that make up 75 percent of the world’s dog population, James Gorman writes for The New York Times.
“There are millions of dogs in the world and the vast majority of them are not purebred,” Boyko tells Ed Yong for The Atlantic. “And very little is known about these free-ranging, village dogs.”
While past studies have focused on the lineages of different dog breeds, Boyko decided to look for their birthplace by examining their genes. For seven years, Boyko and his team traveled around the world collecting blood samples from 5,392 dogs from every continent but Antarctica, including 549 village dogs.
In the end, they examined 185,800 different genetic markers, making this the largest study of the genetic diversity of dogs in the world, Grennan Milliken writes for Popular Science.
According to Boyko’s research, the most genetically diverse dogs were found in Mongolia and Nepal, while those furthest away from Central Asia were the least diverse. The closer his samples came to this region, the more diverse they became.
“It mirrors what we see in humans and how they spread out of East Africa,” Boyko tells Milliken.
While the study’s methods and scope impressed some researchers, not everyone is convinced that Central Asia is the dog’s definitive birthplace.
“Will this be the last word in dog domestication? I highly doubt it,” the University of Oulu’s Olaf Thalmann, who was not involved with the study, tells Yong. “I personally think that we reached a dead end with inferences from modern data.”
Just as new fossils shed light on our own ancestors, the fossil record might be scientists’ best bet to discover where those same ancestors tamed our first pets.