Wolves may have first been domesticated as dogs for their meat, a process that started in southern China.
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.
There is a long tradition of eating dogs in southern China.
In Taming Dogs, Humans May Have Sought a Meal. NYT, 2009.