Actually, they weren't wild dogs. They were wolves. Wolves are the ancestors of dogs. The theory is that wolves and humans found mutually beneficial reasons to hang around each other. Perhaps, human's garbage attracted some tamer wolves, who found it advantageous to stay close to humans. Humans may have been drawn to wolves because they could provide some kind of protection from other predators. As some wolves stayed close to humans, the tamer wolves interbred, producing not only more tame wolves, but other characteristics that seemed to be linked the tame characteristics. Gradually the animals changed to look and act more like dogs, which humans learned to breed for desired characteristics.
