http://www.radiolab.org/2009/oct/19/new-nice/

At the same time that wolves became dogs, Neanderthals became us! In both case, the same physiological differences are evident. As the foxes pointed out, neoteny ( the 
retention of juvenile traits into adulthood)occurs when you you breed 
for tolerance of other species.Wolves who could tolerate humans 
could feast on our waste, humans who followed the wolves could more 
easily locate prey. Eventually this led to a symbiosis in which dogs 
located prey and held it at bay for the humans to come in and make a 
quick kill. Thus one man with six dogs could out-hunt twenty men without dogs - a true evolutionary advantage!
Neanderthals died out because the didn't like pets and thus could not compete.
According to DNA evidence, this process began in humans about 500,000 
years ago, although the full physiologic changes are not evident until 
about 50,000 years ago. In dogs these changes (DNA and physiology) occur
 at about 150,000 years and 15,000 years.

Ray Audette
Author "NeanderThin"