Hey, Mr. Wizard, why do we cry?
Well, C-Dawg, the tears produced by our lacrimal glands rinse away the microscopic dust accumulated on our eyeballs, assisted by the wiping action of our eyelids when we blink.

Trust a scientist not to get it.

As babies, we cried. Sure, we cried when we were hungry, or ensconced in a soiled diaper, but that was just because we didn't know the words. We really cried when Mommy left us alone. We'd learned that something about our crying brought her running back every time.

But our power over her eventually faded away.

Later our crying became mostly related to physical injury. The first time we touched the hot stove -- they could probably hear our bawling two towns over. We ran home crying the first time the school bully beat us up. But Dad probably put a stop to that.

But eventually, rather than crying when we hit our thumb with a hammer or drinking a too-hot beverage, most of us took to swearing instead. I've often wondered why curse words are so much more effective here than other words. I, and I would guess many others, have tried on occasion to reprogram my reflexes to a more polite ejaculation, but the order to utter a "Golly" when I stub my toe just didn't take.

Now, as adults, our crying seems to be triggered by strong emotion. We cry when Mom or Dad dies. We cry when that special someone ignores us. But it's not just the sad things that can turn on the waterworks. We might cry at a sentimental word from that same someone. And, of course, Moms are famous for crying at their child's wedding. It can even be something we know in our minds to be unreal, but the heart has to have its way. They don't call 'em tear jerkers for nothing. We've all got at least one.

Sometimes, of course, the men in the lab coats can still give a reason. I'm sure there have been learned scientific papers written detailing the precise mechanism and evolutionary reason that we cry when we cut onions.

But mostly we don't know why we cry into our pillows, why we scream at the person who's not there.

I just know it helps.