OK - so this has nothing to do with anything, but I'm curious. I am visiting my sister-in-law and she has two dogs - a black lab and a bassett hound. Then we arrived with our rat terrier. This morning I was watching the three of them playing and it struck me just how different the three dogs are. If I didn't know they were all dogs, I never would have guessed. So - what is the defining characteristic that makes a dog a dog? When you look at cats, they all look basically the same - sure there are some differences, but nothing like the differences between dogs. Horses, cows, pigs, etc... there are differences, but they all look basically the same. But dogs? If I didn't "know" they are all dogs, I would never guess. Any ideas on what makes a dog a dog?