I first saw the idea on a documentary about dogs perhaps 15 years ago. He (I don't remember his name) thought that dogs and Homo sapien sapiens may have cohabitated for a lot longer than the current accepted time length and that dogs probably helped Homo sapien sapiens to live better than neanderthals. Dogs could guard and sound the alarm quicker than any Homo sapien (better hearing and smell) and they could also aid in hunting. I thought it was interesting. But the idea was not presented in any way that approached scientific. It was just some guy's opinion.
When I go camping or hiking with my dogs (German Shepherd-Rottweiler-Lab-mix, purebred Lab), it seems so obvious that dogs can be a SIGNIFICANT benefit to people in "the wilderness." The mix-breed can find our trail after I lose it, my truck, vault-toilets, water, bedding areas of animals like deer and water fowl, deer poop, and horse poop --- all that is natural ability --- no special training. The lab does have some formal hunt training. She can find certain things on command. Not only is her stronger sense of smell a benefit but she will go into areas which are less safe for me (thorny thickets).
Apparently, evidence is building that supports the idea that dogs may have been important to Homo sapien sapiens survival.
Some summary points:
*The new date of dog-human cohabitation is now thought to be around 30,000 --- the same time as the neanderthal extinction. Many believe that sapiens out-competed neanderthals by adapting better tools and hunting techniques. Dogs, of course, would be among those new tools and hunting techniques.
*Dogs and sapiens are the only two known species that use pointing gestures.
*Dogs, wolves, and sapiens are all species that use gaze gestures.
*Sapiens are one of the few species that have "whites of the eyes" which is critical for using gaze gestures at longer distances.
The new article can be found here: http://www.americanscientist.org/issues/pub/do-the-eyes-have-it/2
Information about the pointing gesture: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0030913