Why do people smile?

I’ve often wondered why people smile. What is “happy” and why do we demonstrate it in such a fashion. We don’t often smile on our own; it’s more of a social function. The other day while playing with a friends new born child I was fascinated by its smile and the effect it had on its audience. Adults would perform various antics in an attempt to get the child to smile. It would smile when someone performed a new antic or new sound and I felt compelled to join in. It occurred to me that a child is using a smile to provoke us to interact with it. To help its development. When it stops smiling people try harder. When it smiles people repeat or continue their behaviour until the child stops smiling. So it seemed reasonable to assume that a child smiles at the unexpected – something it has not learnt or does not expect. If we think about ourselves as adults – we smile at jokes when the punch line was unexpected; showing those around us that we've learnt something new encouraging them to continue to teach us. So perhaps the smile is saying to people “I can learn something from you”. It encourags people to continue. Perhaps the ideal strategy is to smile all the time? Maybe it is. But often it's involuntary; something difficult to control. Although some people do seem to smile a lot more than others - take the people of Jamaica? There is something that also inhibits our smile - social hierarchies. People often smile at their superiors; subconsciously showing them their interest to learn, yet people in senior positions often smile less often at their subordinates.