Researchers believe wolves were rescued by European hunters 18,000 years ago, and evolved into modern-day dogs over time.
"We found that instead of recent wolves being closest to domestic dogs, ancient European wolves were directly related to them," Robert Wayne, a professor of ecology and evolutionary biology in UCLA's College of Letters and Science and senior author of the research, said. "This brings the genetic record into agreement with the archaeological record. Europe is where the oldest dogs are found."
The researchers included "10 ancient "wolf-like" animals and eight "dog-like" animals" and "77 domestic dogs, 49 wolves and four coyotes" in their study, a UCLA news release reported.
"We analyzed those six genomes with cutting-edge approaches and found that none of those wolf populations seemed to be closest to domestic dogs," Wayne said. "We thought one of them would be, because they represent wolves from the three possible centers of dog domestication, but none was. All the wolves formed their own group, and all the dogs formed another group."
The team suggested a species of wolves that is now extinct was related to dogs more directly.
The researchers looked at the mitochondrial DNA ("tiny sub-cellular structures with their own small genome") of the animals included in the study and compared them with modern day dogs. The researchers found all the modern domestic dogs included in the study could be traced back to ancient European wolves, and were not directly related to wolves from anywhere else in the world or modern-day wild dogs. Their ancestors are not extinct.
"The wolf is the first domesticated species and the only large carnivore humans ever domesticated," Wayne said. "This always seemed odd to me. Other wild species were domesticated in association with the development of agriculture and then needed to exist in close proximity to humans. This would be a difficult position for a large, aggressive predator. But if domestication occurred in association with hunter-gatherers, one can imagine wolves first taking advantage of the carcasses that humans left behind - a natural role for any large carnivore - and then over time moving more closely into the human niche through a co-evolutionary process."
The team believes the ancient wolves followed the migration patterns of humans, and as a result were not as territorial.
"We have an analog of this process today, in the only migratory population of wolves known existing in the tundra and boreal forest of North America," Wayne said. "This population follows the barren-ground caribou during their thousand-kilometer migration. When these wolves return from the tundra to the boreal forest during the winter, they do not reproduce with resident wolves there that never migrate. We feel this is a model for domestication and the reproductive divergence of the earliest dogs from wild wolves."
"We know also that there were distinct wolf populations existing ten of thousands of years ago," he said. "One such wolf, which we call the megafaunal wolf, preyed on large game such as horses, bison and perhaps very young mammoths. Isotope data show that they ate these species, and the dog may have been derived from a wolf similar to these ancient wolves in the late Pleistocene of Europe."
Further testing will be needed in order to confirm the study's findings.
"This is not the end-story in the debate about dog domestication, but I think it is a powerful argument opposing other hypotheses of origin," Waye said.
