Dogs can express their thoughts through body language. And we humans should better understand this fact, if we want to improve our relationship with this animal species. When a dog jumps on a person, it's not always out of joy or excitement. It can be about gaining or assuming control over the act of saying hello, of choosing the type of human-dog relationship (or should we say "dog-human"?) When a dog cannot simply look in your eye, it means that dog is very much intimidated by you, by the environment, or by the situation.