The results revealed that an unexpected and geographically diverse cluster of breedsincluding the Siberian husky, the Afghan hound, Africa's basenji, China's chow chow, Japan's akita, and Egypt's salukiare most closely related to dog's ancient wolflike ancestors. "Dogs from these breeds may be the best living representatives of the ancestral dog gene pool," the researchers wrote.
The finding may back up claims by some experts that dogs originated in Asia and migrated with nomadic humans both south to Africa and north to the Arctic.
The ability to link these diverse African and Asian breeds to a common ancestor reveals an interesting correlation with patterns of human movement, commented Melinda Zeder. Zeder is curator of Old World archaeology at the Smithsonian Institution in Washington, D.C., and expert on animal domestication. "In this way, these modern breeds provide a map of human migration," she said.
The data also confirm the idea that dogs moved with humans from Asia into the New World and were not domesticated from scratch with wolves in North America, said Zeder. Zeder is also a member of the National Geographic Society's Committee for Research and Exploration.
Another surprise for dog lovers is that some purportedly ancient breedssuch as the Ibizan hound, the pharaoh hound, and the Norwegian elkhoundare not included in this ancestral group. "Breeds like the pharaoh hound have long been thought to be quite ancient, descended from ancient breeds pictured in wall art in [5,000-year-old] Egyptian tombs," Zeder said.
These dogs may in fact have been recreated in modern times from European stock to resemble these ancient breeds, Kruglyak said. Or they might have undergone so much mixing with other breeds that it has masked their ancient origins.
The large majority of breeds, however, likely have recent, European origins, according to the authors. A second cluster of dogs consists of mastiff-like breeds, including the bulldog, rottweiler, and boxer. A third group includes ancestors and descendents of herding-type dogs, such as the Irish wolfhound, the collie, the greyhound, and the Saint Bernard. The final cluster includes scent hounds, terriers, spaniels, and retrievers.
Human Health Benefits
The initial motivation for the study was to use dogs as genetic models to study the bases of human diseases like heart disease, epilepsy, or cancer, Kruglyak said.
At least half of the 300 or so known inherited illnesses in dogs are shared by humans, and many of these illnesses are more prevalent in some breeds than others. For example, kidney cancer is common in German shepherds, and eye problems are common in border collies.
Researchers of human diseases often focus on small groups of people known to share a common ancestry. Focusing on each of 400 or more isolated breeds of dogs will help researchers find disease genes far more easily, Kruglyak said, ultimately benefiting humans as well as dogs.
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