I Can't Figure it Out...

What is the biological purpose of crying? I know that in general the tear duct excretes enough fluid to keep your eyes from drying out, but why do we cry?

What is it about extreme emotion that makes our body think we need all that fluid pouring out of our eyes?

I mean I can understand saliva. It serves an important function – an important first step in the digestive process.

I can understand sweat - an important function in the battle to regulate internal temperature.

But what does crying do for us?

The solutions I'm able to turn up on the great InterWeb are nothing more than speculation. The most common theory seems to revolve around pain – the eye's natural reaction to pain is to tear – to keep dirt, and other foreign objects out of your eyes. Emotional pain, is apparently close enough to physical pain that our eyes water. So says the theory.

But what about people who cry when they're happy? Doesn't that kind of throw that line of reasoning out the window? Or are we not limited to pain, but to any extreme emotion? It still seems like quite a logic leap to me...

We learn to cry at a very early age – it's our primary means of defense. When we need anything, we cry. Food, drink, clean diapers, whatever, we cry. The noise makes sense – we need to get somebody's attention. Someone needs to help us, because we can't do it for ourselves. But the tears still have no place. I can almost understand the facial contortions involved in crying... A non-verbal, 'I've got problems' signal to anybody nearby.

I don't know. Apparently, nobody else does either...

I'm going to be late for work...