We share the planet with 400 million dogs: toy dogs, working dogs, champion dogs and artistic dogs; dogs who know what to do in an emergency; and dogs who know their way around a couch. For over 12,000 years, they’ve been our security guards and our friends. But how smart are dogs? Most dog owners would say they’re geniuses…and point to their own pup as living proof. National Geographic joins scientists and dog trainers to investigate canine intelligence .