I came across some very interesting reading over the last month.  Some of it has to do with an article that was published by Nature Australia Vol. 27 2002.  The article was written by Dr. Paul Tacon, Principal Research Scientist at the Australian Museum and Colin Pardoe, a consultant in the field of bio-archeology.  These two men have been collaborating on research that shows a deeper and longer connection between humans and dogs than earlier studies have indicated.
While archeological evidence has shown domesticated dogs were part of human culture as far back as 13,000 years ago, Tacon & Pardoe believe that humans first began to domesticate the wolf about 135,000 years ago.  Their research points towards a deeper cooperation and level of interaction than anyone would have guessed.
The archeological evidence that is often cited in the scientific literature is based on 13,000 year old dog skeletons that had been carefully buried along with human remains.  A DNA study, performed by Dr. Robert Wayne of UCLA, shows that dogs began to genetically diverge from wolves over 100,000 years ago.  The question is why there so few dog remains older than 13,000 years?  It appears the answer is because we should have been looking for wolf bones instead.
The fossil record does show a lot of examples of wolf bones and human bones in close proximity to one another during this period, over 100,000 year ago just as homo-sapiens was evolving from homo-erectus.
Tacon and Pardoe believe that humans and wolves entered into a symbiotic relationship in which the humans not only domesticated the wolves, but to a significant degree the wolves domesticated the humans as well.
Some of the evidence for this has to do with brain-size.  All domesticated animals have smaller brains than their wild counterparts. Domesticated horses, pigs, and sheep have less need for certain parts of their brain than they did in the wild so these parts are reduced in size over a period of generations.  
The same is true for dogs.  Their brains are smaller than wolf brains. Human brains also began to show a reduction in size about 10,000 years ago, not long after the domestication of the wolf/dog was complete.  The parts of the human brain that saw the most radical decrease in volume were the olfactory bulbs.  These are the areas of the brain that allow dogs to have such an amazing sense of smell.  The reduction in size of the human olfactory bulb is now believed to have a strong link to man’s partnership with the wolf/dog!
By partnering with dogs humans gained a huge advantage over other predators.  The scenting abilities, speed and teeth of the dog enabled humans to excel at hunting, to protect their offspring and defend their territory in ways that would have been impossible without the help of the dogs.  
Some biologists think the evolutionary reduction in the size of humans’ olfactory bulbs was due to the cooperation with dogs.  An acute sense of smell was not necessary for humans because of our partnership with dogs; so we developed larger frontal lobes in their place.  The larger frontal lobes suited the new role of humans as the organizers and planners in the human/canine partnership.
Archeologists also point out that before humans partnered with the wolf; man was a lone hunter mostly pursuing small animals.  It was only after man began to hunt with wolves that he learned to hunt in teams in pursuit of large animals.
Anthropologists believe that humans of this period were not nearly as social as they were in later periods.  Relationships outside of kin were rare or non-existent as they are in modern non-human primates.  Humans lived in small bands of related individuals.  Anyone outside of the band was an enemy.  These roving bands raided and warred with each other to secure mates and slaves.  Wolves, on the other hand are social within family groups, but also form friendships with wolves outside of kinship.  There is speculation about the possibility that dogs are responsible for humans developing social behavior!
These are just a few bullet points from some of the research that is going on regarding the history of the human/dog partnership.  You can find more on this fascinating subject in a book by Temple Grandin entitled Animals in Translation.