"How are you" is a question that replied almost with lies. It is also a question which most often answered as if the person asking it was really interested. Social convention and man's general lack of sincere interest dictate it. When you say "I am fine" you may say it as a declaration of how you are determined to feel. Or when you smile, it may express your determination that you want others to feel happy. Language is not just about factual statements. It is about anticipations, real questions, rhetoric questions, irony, intent, alegory, rituals.