Published: Mon, July 09, 2018
Medical | By Marta Holmes

How an entire line of dogs in the Americas disappeared

How an entire line of dogs in the Americas disappeared

To dig a little deeper, we took DNA from ancient dog remains, spanning roughly 9,000 years of dog evolutionary history, from sites across North America and Siberia, and compared this with CTVT.

The team collected genetic information from 71 ancient dog remains from the Americas and found that early dogs arrived alongside people who eventually settled throughout North, Central and South America.

"This suggests something catastrophic must have happened, and it's likely associated with European colonisation", says Laurent Frantz from the University of Oxford.

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The new findings reinforce the idea that early human and dog inhabitants of the Americas faced numerous same challenges after European contact, Malhi said.

Thus, it's a mystery as to where and how these early domesticated dogs evolved. The findings "put a nail in the coffin really for [that] idea,"Perri told Live Science". Scientists found that the ancient dogs came first from Siberia, and that modern American breeds share few common genetic connections. Still, it does look like they are mostly European in origin.

"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", said Kelsey Witt, an author of the study and the one who led the analysis of the sample DNAs. Those include arctic dogs brought by the Thule people about 1,000 years ago that are the ancestors of dogs such as malamutes, huskies and Greenland sled dogs; dogs brought by Europeans starting in the 15th century; and Siberian huskies brought to the American Arctic during the Alaskan gold rush. "We suspect that a lot of the reasons [ancient] dogs were wiped out, were similar reasons that Native American populations were destroyed", Perri said.

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At this time, the landmasses now known as Russian Federation and North America were not separated by water, but connected by a continuous expanse of land, the Bering Land Bridge. But it's probably a combination of things, she added. While unsampled pockets of American dogs might still remain, what we've found so far suggests that they have been extensively replaced by European breeds. Evidence that these dogs were used in sledding, along with suggestions that they were used for hunting and hauling, means that they could have facilitated the early settlement of the Americas. But though this lineage thrived for centuries, it seems their fate was inextricably tied to the indigenous people who were killed by the Europeans. The experts received samples of dogs during the excavations held in the territory of modern IL.

Less controversial is the researchers' theory about the canine transmissible venereal tumour (CTVT), a sexually transmitted form of cancer that has spread globally. What we found was a huge surprise. "The genome that it has is the genome of the very, very first" dog to get the disease. Though more research is needed to confirm the hypothesis, "such a scenario is entirely plausible", he said. These ancient American dogs lived for about 10,000 years until they were nearly wiped out by the European breeds that, on the other hand, tagged along with their European humans as they colonized the continent. Instead, the analysis confirmed, the dogs were most closely related to an ancient Eastern Siberian stock.

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