The dog has so many fine qualities it is hard to know which it was prized and bred for by the early people who first domesticated its noble ancestor, the wolf. Was it the dog’s valor in the hunt, perhaps, or its role as night watchman, or its strength in pulling a sled, or its companionable warmth on cold nights?

A new study of dogs worldwide, the largest of its kind, suggests a different answer, one that any dog owner is bound to find repulsive: wolves may have first been domesticated for their meat. That is the proposal of a team of geneticists led by Peter Savolainen of the Royal Institute of Technology in Stockholm.

Sampling the mitochondrial DNA of dogs worldwide, the team found that in every region of the world all dogs seem to belong to one lineage. That indicates a single domestication event. If wolves had been domesticated in many places, there would be more than one lineage, each leading back to a local population of wolves.

The single domestication event seems to have occurred in southern China, where the dogs have greater genetic diversity than those elsewhere. The region of highest diversity is usually the place of origin because a species tends to lose diversity as it spreads.