A fossil tooth found in Siberia has yielded DNA evidence it belonged to one of the oldest known ancestors of the modern domesticated dog, researchers say. The DNA analysis was carried out on a fossil skull found in the Altai Mountains in 1975. Although human domestication of dogs predates the beginning of agriculture about 10,000 years ago, the timing of when modern dogs emerged as a species distinct from wolves is still unclear, they said. The new analysis shows the 33,000-year-old Siberian fossil, from a creature dubbed 'Altai dog' after the mountains where it was recovered, is more closely related to modern dogs and prehistoric canids found on the American continents than it is to wolves, Anna Druzhkova from the Institute of Molecular and Cellular Biology, Russian Federation, and colleagues said. "These results suggest a more ancient history of the dog outside the Middle East or East Asia, previously thought to be the centers where dogs originated," the researchers wrote in the journal PLoS ONE.