|"I evolved from a ruthless hunter/scavenger, got any bacon?"
As the story goes, these tame wolves bred with other tame wolves and became juvenilized. Think of them as wolves-lite, diminished in strength, stamina and brains. They resembled young wolves, with piebald coats, floppy ears and shorter, weaker jaws.
But it was never clear, in this old account, just how we got from the scavenging wolf to the remarkable spectrum of dogs who have existed over time, from fell beasts trained to terrorize and kill people to creatures so timid that they flee their own shadows. The standard explanation was that once the dump-diver became a dog, humans took charge of its evolution through selective breeding, choosing those with desired traits and culling those who came up short.
The first major challenge to the consensus came in 1997, when [s]cience plac[ed] the origin of the dog as early as 135,000 years ago. Their date was based on analysis of mitochondrial DNA, which is passed on to offspring through females and is believed to change little from generation to generation; it allows scientists to calculate the time when populations or species separated genetically. This analysis suggested that wolves could have become dogs wherever in Eurasia they associated closely with early humans, and that even after the split was made, dogs and wolves continued to interbreed.
Academics aside, click the source link, good stuff.
Source -> http://online.wsj.com/article/SB10001424052970203554104577001843790269560.html?mod=e2tw