Everything You Ever Wanted To Know About Dogs (9 pics)

When your dog is growling and snarling while you play tug-of-war him, he's growling at the rope or toy you're both pulling on, not you. Your dog perceives this as teamwork to rip apart a prey animal, which is a pack behavior that releases loads of happy chemicals (endorphins) into their brains. Get down on the floor, have a good growl with him, and enjoy your own endorphins!

Also, dogs can sense time through changes in smells. Experiments have shown that dogs sense when you're due to come home from work because your smell has been steadily dissipating from the house while you've been gone. Now, how they know you're on your way home from the store on Saturday afternoon when you're still miles from home is still a mystery.