No-one doubts that "man's best friend" is an evolutionary off-shoot of the grey wolf, but scientists have long argued over the precise timing and location for their emergence.

The new research, based on a genetic analysis of ancient and modern dog and wolf samples, points to a European origin at least 18,000 years ago.

Olaf Thalmann and colleagues report the investigation in Science magazine.

It adds a further layer of complexity to the story.