NOVOSIBIRSK, Russia, Aug. 3 (UPI) -- A 33,000-year-old well-preserved canine skull from a cave in Siberia shows some of the earliest evidence of man's domestication of the dog, researchers say.
The skull is unlike those of modern dogs or wolves, researchers said; while the snout is similar in size to early, fully domesticated dogs from 1,000 years ago, its large teeth resemble those of 31,000-year-old wild European wolves.
This suggests a dog in very early stages of domestication, research team member Susan Crockford told the BBC.
"The wolves were not deliberately domesticated; the process of making a wolf into a dog was a natural process," Crockford, an evolutionary biologist, said.
But the domestication process was an outcome of settled human populations, she said.
"At this time, people were hunting animals in large numbers and leaving large piles of bones behind, and that was attracting the wolves," she said.
And it was attracting the most curious, least fearful wolves -- almost always juvenile -- with shorter, wider snouts and smaller, more crowded teeth.
These features, over generations, came to define the domesticated dog, Crockford said.
In the last 10,000 years the gradually domesticated dogs became more and more valuable to humans as hunting helpers, another researcher said.
"When you've got hunting dogs, all of a sudden it's a game changer," Oxford University archaeologist Thomas Higham said. "Hunters with dogs are much better than sole hunters."