Well, we've been together for over 15,000 years.

Granted, during that time our impact on the evolution of dogs has been vastly greater than their effect on us, but dogs have definitely affected us culturally, if not so much evolutionarily.

Check out the article above. The results of the research they mention are pretty damned interesting, suggesting that a great deal of dogs' predispositions to human interaction are genetically hardwired, as opposed to being learned. They responded more acutely (both adult dogs and puppies) to human cues than either wild wolves or chimpanzees (both of which have larger brains).

People who have dogs note the often human-like behavior they exhibit. They respond so well to us because we've selected dogs that have desirable attributes (physical appearance, friendliness, and responsiveness) for over 15,000 years.

Cats, on the other hand, were most likely domesticated between 4-6,000 years ago by the Egyptians.

We've lived with dogs nearly three times as long, and the power of Artificial Selection shows.