Tens of thousands of years ago, early humans formed an unlikely partnership with another animal.
The grey wolf.
Over time, the wolves changed in body and temperament.
Their skulls, teeth and paws shrank.
Their ears flopped.
They gained a docile disposition, becoming both less frightening and less fearful.
They turned into dogs.
Scientists agree that all dogs descend from wild ancestral wolves, but they disagree as to when, where and how that happened.
Gregor Larson from the University of Oxford has been trying to get some firm answers.
Already, he and his team have yielded a surprising discovery.