The animals probably didn't change all that much until about 500 years ago, when selective breeding started an avalanche of changes in the canine world, leading to everything from powder puff pooches to Doberman pinschers.
They have found their niche in everything from cheering the elderly to making their owners get out and walk, which by the way, is as good for the owner as it is for the dog, which is likely to be less aggressive if it gets more exercise, according to the Penn study.
Somewhere along the way, of course, the human-canine love fest got a little out of hand. Seriously, folks, one study out of the University of California, San Diego, confirmed a widely held belief that dogs and their owners do tend to look alike. Especially if the dog is a purebred.
But unfortunately, as the Penn study shows, the relationship is not always that harmonious.
A bad dog can be a serious threat to humans, especially children, and the vets caution that when a dog goes bad, professional help is essential. Kicking the animal won't help, and could make things worse.