Ancient dog cancer still around today after 10000 years

A 10,000-year-old dog burial at the Koster site in western Illinois.    
        
        Del Baston courtesy Center for American Archeology

A 10,000-year-old dog burial at the Koster site in western Illinois. Del Baston courtesy Center for American Archeology

"It is known how Indigenous peoples of the Americas suffered from the genocidal practices of European colonists after contact", author Ripan Malhi, an anthropology professor at the University of IL, explains. But Perri expects that there are many older ancient dogs yet to be found, since the first concrete evidence of human arrival to America was dated to 4,500 years before that.

Alaskan malamutes, like this one at the 2016 Westminster Dog Show, are among the oldest dog breeds in North America.

In the study, the researchers took DNA samples from dog remains that spanned time (throughout thousands of years) and space (North America and Siberia).

As Anna Linderholm, an assistant professor of anthropology at Texas A&M University who did much of the genome sequencing said, humans are predisposed to bringing their dogs along with them, and Europeans also brought their dogs when they discovered the New World. Instead, these dogs shared an ancestor with the husky.

A study suggests ancient dogs came from Siberia by tagging along with their humans over a land bridge that once connected North Asia and the Americas. They could also be killed purposely by the Europeans like what they did with the indigenous people.

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. People in Europe and the Americas were genetically distinct, and so were their dogs.

"If there were millions and millions of dogs all over this continent, and a small number of European dogs came in, there would have been plenty of time for them to do what dogs do, which is mate with each other and leave their DNA behind", Karlsson said.

DNA analysis allowed the scientists to identify pre-contact dogs' closest relatives: a group of dogs native to Zhokhov Island, a frigid Arctic site situated about 300 miles north of the Russian mainland.

Lead archaeologist Dr Angela Perri from Durham University, co-first author on the study, added: "Archaeological evidence has long suggested that ancient dogs had a dynamic history in the Americas, but the fate of these pre-contact dogs and their relationship to modern American dog populations was largely unknown".

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.

Because of that, Savolainen doesn't discount the possibility that while these pre-contact dogs might not have direct living descendants, earlier migrations could have brought over dogs whose genetic legacy has survived into the modern day.

Modern dogs, the study reveals, contain nearly no traces of those original dogs with one big exception: a cancer that is spread from dog to dog through mating, resulting in a malignant tumor.

However, the organism that was found to be the most closely related to the vanished lineage of American dogs is Canine transmissible venereal tumor or CTVT, which is a contagious type of cancer afflicting dogs.

"This study demonstrates that the history of humans is mirrored in our domestic animals". Researchers compared the 71 ancient genomes with DNA from more than 5,000 modern dogs, including breeds like chihuahuas and Carolina dogs, which are commonly thought to be descended from indigenous populations.

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