Why do we show expression?

Question

Why do we laugh when something is funny?
Why do we cry when we're sad or happy?
Why do we smile when we're happy?
Why do we yawn when we're tired?
Why do we scrunch our eyebrows when we're mad or disgusted?

Answer 1

As True says--also expression is a form of communication--expressions aid the other person's understanding of what we are saying. I've read that 60% of meaning that we get from another person comes from their body language--which includes our facial expressions. If we had no expressions, we'd often have to guess what the other person is saying and feeling and probably be wrong most of the time. We'd have a tougher time communicating with each other.----laughing, crying release tension (laughter--surprise, etc.) and stress--all essential in our well being. Yawning is usually when we're needing more oxygen--but why when we're sleepy we'd need more oxygen, I don't know. We're pretty complex organisms.

Answer 2

We show expression because of a natural reflex.
Such as:
When something is funny, we laugh because of a reaction in our brain which is the same with all of your questions.