"We found that instead of recent wolves being closest to domestic dogs, ancient European wolves were directly related to them," said Robert Wayne, a professor of ecology and evolutionary biology in University of California - Los Angeles' College of Letters and Science.
"This brings the genetic record into agreement with the archaeological record. Europe is where the oldest dogs are found," said Wayne, senior author of the research.
In related research last May, Wayne and his colleagues reported at the Biology of Genomes meeting in New York the results of their comparison of 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 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," Wayne added.
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For the current study, published in journal Science, the researchers studied 10 ancient "wolf-like" animals and eight "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.
By comparing this ancient mitochondrial DNA with the modern mitochondrial genomes of 77 domestic dogs, 49 wolves and four coyotes, the researchers 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, researchers concluded, derived from ancient wolves that inhabited Europe and are now extinct.
They estimated that dogs were domesticated between 18,000 and 32,000 years ago.