A 10,000-year-old dog from an archaeological site near Eldred, Ill., known as the Koster site, where the earliest known dogs in the Americas were found.
Del Baston/Center for American Archeology
discovery / science

The Lost Dogs of the Americas

Exhaustive DNA studies find that the dogs of European colonists completely replaced ancient American dogs.
Before Europeans began to colonize the Americas about 500 years ago, the land, north and south, was populated with people who had been here for thousands of years. And their dogs.

The devastation visited on the native human inhabitants of North and South America is well known. Whether their dogs survived in some form, perhaps only as a portion of the DNA of some modern dogs, has been a matter of dispute. The available evidence indicated that only traces were present in current breeds and mixed breed dogs, but questions remained.

An international team of researchers who conducted the most detailed and thorough study yet of ancient and modern dog DNA reported Thursday in the journal Science that new evidence overwhelmingly suggests that the so-called pre-contact dogs have disappeared to an extent similar to the Neanderthals. The study found no more than 4 percent of pre-contact dog DNA in any sample, and those results could be interpreted as zero. By comparison, some modern humans may have a bit more than two percent Neanderthal DNA

In a macabre scientific twist, the new study found that the closest living DNA match to the pre-contact dogs is a strange, but well known cancer, a tumor in which the cancerous cells themselves spread from dog to dog during sex, like rogue tissue transplants.Called canine transmissible venereal tumor, it originated thousands of years ago in one dog, probably from East Asia. The cancer is now present worldwide, still carrying the genome, much mutated but still identifiable, of that original host dog. 

Greger Larson at the University of Oxford, an author of the paper, and the leader of an international effort to investigate the evolution and domestication of dogs, said the study emphasizes how inseparable are the fates of humans and their animals.
  …
View source