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Dear Dr. Universe
Why do we cry?
Shannon Wainwright
South Africa
Hard as it is to believe, hardly anyone studies crying. As a scientist buddy told me the other day, "It's just TOO BIG A QUESTION."
But we've never let that stop us before!
So I tracked down Paul Verrell here at Washington State University. He studies animal behavior. (He is also one of those rare scientists who is willing to SPECULATE.) Much thinking about behavior is also about evolution, because that's where much of our behavior comes from. So when Professor Verrell asks why, he asks WHY.
Let's start with the idea that crying is a form of communication. (Now keep in mind we're SPECULATING here.) In fact, it's a very young baby's ONLY form of communication. Imagine yourself, lying on your back, staring out at this very weird new world. You can't talk or crawl or even think or see very clearly. But your body says: "I'M HUNGRY."
Scientists who think about evolution think a lot about "evolutionary advantage." Basically, an evolutionary advantage helps you survive so you can pass your genes on to your descendants. And your genes aren't going to get passed on if your body doesn't get FED. So you scream!
Maybe my friend here just needs to give in to ritualization.
(The painting is Absinthe (1876) by Edgar Degas.)
Technically, if you're less than two months old or so, you're not really crying—if you define crying as shedding tears. Babies don't start crying tears until they're about two months old. But screaming gets results, and the tears get connected later.
Actually, there are three kinds of tears. BASAL tears lubricate your eyeball. Your eyeball is really not very smooth, so without tears to smooth it over, you wouldn't be able to see very sharply. Various tear glands produce about 5-10 ounces of basal tears daily. These tears flow over the eye and into the LACHRYMAL ducts in the inside corners of your eyes and then into your nasal cavity.
REFLEX tears protect your eyes against irritants, such as onions, and foreign objects or blows.
Now get this. There's a big difference between EMOTIONAL tears and these other kinds of tears. Emotional tears contain 20-25 percent more protein, including various hormones! So what does this mean? WE DON'T KNOW, BUT IT IS VERY INTERESTING.
Actually, some scientists think tears are a way for the body to get rid of wastes, as is sweating or defecation.
On the other hand, maybe crying is a functionless byproduct of increased autonomic activity in distressed individuals. WHAT?! Pat Carter is an evolutionary physiologist here at WSU. He studies how our bodies came to do the things they do over the course of time. He is very careful about trying to guess why something like crying developed. Maybe it developed as the result of something that we're not aware of.
Well, says Professor Verrell, maybe so. Still, crying would continue to exist through human evolution IF IT TOOK ON A FUNCTION. So what might that function be?
Communication!
Behaviorists call this process -- of a byproduct taking on a new function -- RITUALIZATION.
Professor Verrell compares this to a dog's peeing when it gets excited or runs into something new. Over time, peeing seems to have transformed, or ritualized, from an autonomic response into a form of communicating where its territory is.
Professor Verrell says that communication signals that have evolved through ritualization are usually stereotyped, exaggerated and repetitive. So MAYBE crying came to be because the people (babies and others) who cried hardest, longest and loudest were most likely to get food or help.
But wait! you say. You're not done yet. What about sadness and anger and grief and other reasons we cry?
We don't know. Maybe Aristotle and others long ago were right. Maybe crying is a means of cleaning yourself out emotionally. Or maybe it's your communication of last resort, the only way to express yourself when words fail, the same as when you were a baby and had no words.
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