Dogs and Humans - How the relationship began
(excerpt from The Intelligence of Dogs)
Dr. Stanley Coren
"...We will probably never have conclusive evidence to tell us how dogs and humans first formed their personal and working relationship with each other, but it is most likely the case that man did not initially choose dog; rather dogs chose man. Dogs were likely attracted to human campsites because humans like dogs were hunters, and animal remains, such as bones, bits of skin, and other scraps of offal from the victims of recent hunts, were likely to be scattered around human campsites. The ancestors of today's dogs (being ever food conscious) learned that by hanging around man's habitations, they could grab a quick bite to eat now and then, without all the exertion involved in actual hunting.
Although primitive man may not have been very concerned with cleanliness, health issues or sanitation, it is still true that rotting food stuff does smell, and attracts insects that will make humans uncomfortable. Thus it is likely that dogs were initially tolerated around the perimeter of camps simply because they would dispose of the garbage. This waste disposal function continued for countless centuries and is still being fulfilled by the pariah dogs in many less developed regions of the world. Anthropologists studying primitive tribes in the South Pacific have noticed that on those islands where people keep dogs, the villages and settlements are much more permanent. Villages without dogs have to move every year or so simply to escape the environmental contamination caused by rotting refuse. This has even led to the suggestion that dogs may have been a vital element in the establishment of permanent cities in that bygone era before we learned the importance of public sanitation.