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+--- Thread: North America's 1st dogs disappeared, left behind sexually transmitted cancer (/thread-5685.html)
North America's 1st dogs disappeared, left behind sexually transmitted cancer - C C - Jul 7, 2018
https://www.sciencealert.com/first-dogs-america-extinction-ctvt-disease-legacy
http://www.gizmodo.co.uk/2018/07/americas-first-dogs-were-wiped-out-by-europeans-but-their-genetic-legacy-lives-on-as-a-sexually-transmitted-cancer/
EXCERPT: . . . Confirming earlier work, the researchers found these ancient American dogs have very little in common with modern dogs today, genetically speaking. And they also have no common ties with the North American wolf, suggesting they weren’t tamed from the local canine population the proto-Americans encountered. But these dogs did share more genetic similarities with breeds such as the Siberian Husky, though not as direct descendants. Instead, these dogs shared an ancestor with the husky.
[...] From their origins in Siberia, the dogs spread down through the continent with human settlements, becoming partially or even completely domesticated as the years ticked by. It's likely they looked somewhat similar to the wolves that preceded them by a few thousand years, also journeying across the land bridge formed by the Ice Age's lowered sea level. The 19th century American naturalist John James Audubon remarked, "The Indian dogs which I saw here so very closely resemble wild wolves, that I feel assured that if I was to meet with one of them in the woods, I should most assuredly kill it as such."
[...] Today these wolf-like dogs are no more. Their disappearance coincided with colonisation, their ultimate fate left to speculation. "This suggests something catastrophic must have happened, and it's likely associated with European colonisation," says Laurent Frantz from the University of Oxford. "But we just do not have the evidence to explain this sudden disappearance yet."
[...] While some American dogs might have been wiped out by epidemics or purposefully killed by Europeans, as indigenous people often were, there are likely other reasons for their demise. [...] The results seem to undercut the popular narrative that breeds such as chihuahuas are descended from ancient American dogs, since their mitochondrial DNA had less than 2 per cent in common with the ancient dogs in this study. Not every expert is convinced that’s the case, though.
[...] Less controversial is the researchers’ theory about the canine transmissible venereal tumour (CTVT), a sexually transmitted form of cancer that has spread globally. Because CTVTs (and all cancers) are essentially the mutated form of an animal’s DNA, it’s possible to trace back its genetic structure to the dog who first developed it. And the researchers found that this “CTVT founder” dog was closely related to pre-contact dogs, suggesting the disease had originated some 8,000 years ago...
MORE: https://www.sciencealert.com/first-dogs-america-extinction-ctvt-disease-legacy ... http://www.gizmodo.co.uk/2018/07/americas-first-dogs-were-wiped-out-by-europeans-but-their-genetic-legacy-lives-on-as-a-sexually-transmitted-cancer/