Physical depiction of emotions

Laughter, as a muscular response, seems to depict itself the same way in every culture.  How did man first equate positive feelings with chuckling, positioning jaws or curvature of mouth? Normally pleasure/happiness triggers smiling, even babies show intriguing behaviour towards positive conditions like comfort. A baby cant analyze and reply accordingly by prior experience so how does it exactly assign the action to stimulus? Is it copying the parents  handling  baby care by simultaneously matching gestures to actions? May be, but that also points out a child can be brought up with mismatched values and inappropriate responses. Fear or anger can be confronted calmly. Odd combinations may be created too, like shutting one eye twitching the other and clenching teeth when feeling curious. As straining as it seems, laughing or crying are no less of efforts for facial muscles. Take crying for instance, what an unusual case tearing is. Yawning?

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why are you offensive? what is wrong with thinking? before learning from a source, thinking should be the first choice since the source also thought that up at some point. facts supporting it or not doesn't matter, you can find evidence for anything if you search for it. ( why are there religious people out there)
And about being instinctive, i was covering that. We are aware of fundamental instincts like the urge for survival or fear or hunger but if the expression of laughing is instinctive that has to be learned in time and coded in genes later on. And so question stands: why did the first guys choose that kind of facial expression to show they are happy?