European settlers likely wiped out these ancient dogs, but the animals seem to have left a lasting legacy in a transmissible canine cancer.

The first domesticated dogs to be kept in the Americas were not descendants of North American wolves, as sometimes suggested, but were brought across from Siberia by humans more than 10,000 years ago, according to a study published today (July 5) in Science. By analyzing ancient and modern dog genomes, researchers also found that, despite surviving alongside humans for millennia, those animals were all but wiped out with the arrival of European settlers from the 15th century, who brought other dogs that would become the ancestors of modern North American breeds.

“It is fascinating that a population of dogs that inhabited many parts of the Americas for thousands of years, and that was an integral part of so many Native American cultures, could have disappeared so rapidly,” study coauthor Laurent Frantz of Queen Mary University and the University of Oxford says in a statement. “Their near-total disappearance is likely due to the combined effects of disease, cultural persecution and biological changes starting with the arrival of Europeans.”

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. “We now know that the modern American dogs beloved worldwide, such as Labradors and Chihuahuas, are largely descended from Eurasian breeds,” archeologist and coauthor Andrea Perri of Durham University says in the statement.

The team did find one hint of the ancient dogs’ genomes in modern breeds, however. When the researchers analyzed the genome sequence of a contagious genital cancer known as canine transmissible venereal tumors (CTVT), they found that the disease most likely came from the cells of a single animal—one with an ancient dog genome.

“We in other groups have been looking for these signatures of ancient North American dogs in modern breeds,” Heidi Parker, a staff scientist at the Dog Genome Project at the National Human Genome Research Institute who was not involved in the work, tells National Geographic. “The thought that there’s actually a preserved signature of one of those early North American dogs that are extinct today in this tumor, which is just perpetuating it then forever, is very cool.”

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