The dog story: European canines replaced New World's ancient breeds

Washington: Native dogs across North America all but disappeared as a result of Europeans arriving in the Western Hemisphere some 500 years ago, a study published Thursday found.

Researchers found that dogs likely first moved to the New World thousands of years ago, alongside human settlers coming from Siberia across what is now the Bering Strait.

They then lived here relatively undisturbed until European settlers arrived in about the 15th century, whereupon the colonizers' breeds quickly displaced indigenous canine populations.

"People in Europe and the Americas were genetically distinct, and so were their dogs," said Greger Larson, director of the Palaeo-BARN at Oxford and senior author of the study.

"And just as indigenous people in the Americas were displaced by European colonists, the same is true of their dogs."

The findings are based on research by an international team of 50 scientists, who looked at the DNA of the remains of 71 ancient dogs and compared these to modern American animals.

The research was led by the University of Oxford, University of Cambridge, Queen Mary University of London and Durham University.

Scientists found that the ancient dogs came first from Siberia, and that modern American breeds share few common genetic connections.

The oldest evidence for dogs in the Western Hemisphere dates back about 10,000 years, some 6,500 years after the first humans arrived.

These "pre-contact" dogs have few genetic connections to modern American breeds, researchers found.

It appears that native dog populations could have been wiped out through a number of causes, including disease, persecution and Europeans' desire to raise their own breeds.

Modern American dogs like Labradors and Chihuahuas are descended from Eurasian breeds introduced between the 15th and 20th centuries, said lead archaeologist Angela Perri from Durham University in England.

Strangely, the most direct genetic link between ancient American dogs and modern ones is found in a cancerous canine tumor derived from a dog that lived up to 8,000 years ago, the study states.

"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.

"Although this cancer's DNA has mutated over the years, it is still essentially the DNA of that original founder dog from many thousands of years ago."