Alaskan breeds -- such as Inuit sled dogs, the Eskimo dog and the Greenland dog -- are the only canines with actual American roots, according to DNA analysis. All of these pooches hail from the 49th state and nearby areas, according to the study, published in the latest Proceedings of the Royal Society B.
"They are all equally American," co-author Peter Savolainen told Discovery News. "They originate from the indigenous Indian-American and Inuit dog populations, and have only marginally been mixed with European dogs in modern time."
Savolainen, an associate professor at KTH-Royal Institute of Technology in Sweden, explained the determination after tracing the origin of mitochondrial DNA lineages for several dog breeds suspected to be pre-Columbian, meaning before Europeans settled in the Americas. Dogs inherit their mitochondrial DNA from their mothers.
Scientists widely agree that the original stock of all canines worldwide originated from Asia. This is similar to the widely agreed-upon view that all members of our species originated in Africa before some people left that continent.
"There was a single origin of the domestic dog somewhere in Eurasia," Savolainen explained. "The exact place is still debated, but our previous studies strongly indicate the southern part of East Asia, basically southern China."
The earliest archaeological evidence for dogs in the Americas dates to around 10,000 years ago, long before the dawn of transoceanic travel in the 15th century that saw the arrival of Columbus and other Europeans.
Most U.S. dogs today, however, have European origins. Golden retrievers, poodles and many more breeds fall into this category.
Inuit sled dogs, the Eskimo dog and the Greenland dog, though, show no European heritage in their genes. Like Native Americans, they were in the United States and nearby areas long before Europeans arrived.
"Nobody knows exactly what happened," Savolainen said. "Most probably migrated together with the humans that entered America from Asia via the Bering Strait. These humans became today's Indians and Inuits."
"Our data shows dogs came in several migrations, at least one with the Indian-American ancestors and at least one with the Inuit ancestors," he continued.
The result for Alaskan Malamutes was ambiguous, but these dogs appear to come from slightly different stock originating in Siberia, Japan, China and Indonesia. The Alaskan husky and the American Eskimo dog have a known origin from Siberian spitzes and European dogs.
The dogs with the most pre-Columbian Mexican heritage, according to the study, are the Chihuahua and Xolo (Mexican hairless dog).
The researchers additionally determined that a group of free-ranging dogs based in South Carolina and Georgia -- known as Carolina Dogs -- likely have an ancient Asian origin.
Carolina Dogs might have once been associated with a Native American tribe, the canine's relatives turning feral once their humans disappeared.
"The reason might be that the human population keeping these dogs was wiped out when Europeans came," Savolainen said.
Prior research by Sarah Brown of UC Davis and colleagues is consistent with the latest findings about the Inuit sled dog, Eskimo dog and Greenland dog. Brown and her team found "ancient DNA evidence for genetic continuity in arctic dogs."
Scientists hope to use such DNA studies and other research on dogs to learn more about past human migrations. From at least 10,000 years onward, wherever migrating humans went, dogs often came too.