Scientists have analyzed the complete mitochondrial genomes of 18 prehistoric wolf- and dog-like animals to show that more than 18,000 years ago, dogs first became best friends of human in Europe.

“We found that instead of recent wolves being closest to domestic dogs, ancient European wolves were directly related to them,” said Prof Robert Wayne from the University of California Los Angeles, senior author of the genetic study published in the journal Science.

“This brings the genetic record into agreement with the archaeological record. Europe is where the oldest dogs are found.”

In a previous study, Prof Wayne’s team compared the complete nuclear genomes of three recent wolf breeds from the Middle East, East Asia and Europe, two ancient dog breeds and the boxer dog breed.

“We analyzed those six genomes with cutting-edge approaches and found that none of those wolf populations seemed to be closest to domestic dogs,” Prof Wayne explained.

“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 researchers also hypothesized that a now-extinct population of wolves was more directly related to dogs.

For the current study, they studied 10 ancient wolf-like animals and 8 dog-like animals, mostly from Europe. These animals were all more than 1,000 years old, most were thousands of years old, and two were more than 30,000 years old.

The scientists studied the mitochondrial DNA of the animals, which is abundant in ancient remains.

By comparing this ancient mitochondrial DNA with the modern mitochondrial genomes of 77 domestic dogs, 49 wolves and four coyotes, they determined that the domestic dogs were genetically grouped with ancient wolves or dogs from Europe – not with wolves found anywhere else in the world or even with modern European wolves.

“Dogs derived from ancient wolves that inhabited Europe and are now extinct,” Prof Wayne said.

“The domestication of predatory wolves likely occurred among ancient hunter-gatherer groups rather than as part of humans’ development of sedentary, agricultural-based communities.”

“The wolf is the first domesticated species and the only large carnivore humans ever domesticated.”

“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.”

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Bibliographic information: Thalmann O. et al. 2013. Complete Mitochondrial Genomes of Ancient Canids Suggest a European Origin of Domestic Dogs. Science, vol. 342, no. 6160, pp. 871-874; doi: 10.1126/science.1243650