The remains of a 10,000 year-old dog has proved key to solving an important canine conundrum: What happened to the dogs of ancient North America?
The earliest traces of domesticated dogs in North America are from about 5,000 years after humans first arrived about 15,000 years ago.
The findings further suggest that they do not know the exact reason behind the sudden disappearance yet but the researchers believe that the sudden near disappearance is most likely because of the combined effects of the cancer and the European colonization.
Using DNA data from 71 dog remains from archeological sites in North America and Siberia, the researchers found that these ancient, pre-Columbian arrival dogs had very different genetic signatures to any modern dog genomes.
"By looking at genomic data along with mitochondrial data, we were able to confirm that dogs came to the Americas with humans, and that almost all of that diversity was lost - most likely as a result of European colonization", coauthor Kelsey Witt, a graduate student who led the mitochondrial DNA testing, says in a press release from the University of IL.
The genomic analysis showed a transmittable cancer still found among some modern dogs is the only genetic heritage left behind by the disappeared North American dog lineages.
CTVT originated in one dog that lived several thousand years ago and the researchers discovered that the first "CTVT founder dog" was a close relative of early American dogs and that the cancer is still spread through breeds today.
In the study, the researchers took DNA samples from dog remains that spanned time (throughout thousands of years) and space (North America and Siberia). "And just as indigenous people in the Americas were displaced by European colonists, the same is true of their dogs".
Furthermore, "this study for the first time shows that the common ancestry to the original American dogs coincided with the peopling of the Americas", Sacks told Live Science in an email.
"This study demonstrates that the history of humans is mirrored in our domestic animals", Greger Larson, director of the Palaeo-BARN at Oxford and senior author of the study, said in a statement.
The team's findings suggest that modern American dogs are descended exclusively from Eurasian breeds introduced by European settlers.
Thousands of dogs around the world - from Aboriginal camp dogs in Australia to street dogs in Buenos Aires - are affected by an extraordinary type of infectious cancer that causes genital tumours and can jump between individuals, known as Canine Transmissible Venereal Tumour or CTVT. The pre-contact dogs, however, shared genetic similarities with the ancestors of the Siberian Husky.
"It's quite incredible to think that possibly the only survivor of a lost dog lineage is a tumor that can spread between dogs as an infection", said Maire Ni Leathlobhair from the Department of Veterinary Medicine at the University of Cambridge.
Previously the dog family tree was thought to be split into two evolutionary branches- dogs from East Asia, like Chinese village dogs and Tibetan Mastiffs, and dogs from West Eurasia, with modern Arctic dogs falling within both of these groups.
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