The Evolution of a Big, Ugly Cry
Uncontrollable sobbing is uniquely human, and it may be our emotions running out of our faces, a way to connect us with other people
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I cry on a lot of planes, and often for no good reason. I did it just the other day, deep in the throes of a romance novel at 30,000 feet. I’m never a pretty, feminine weeper. Emily Henry’s Book Lovers didn’t leave my eyes delicately swimming with tears. My entire body twisted as I tried to hide gasping, gut-wrenching sobs.
The humiliation of asking a flight attendant for more tissues after blowing through your pathetic supply, trapped in a tiny public space, is compounded by the fact that a good, healthy cry is never simply picturesque droplets coursing down your shining cheeks.
No. Your eyes are red and sore, and your nose will just not stop running. Not the thick gobbets of mucus from the tail end of a cold, but thin, pale streams that trickle obscenely into your mouth. But while that stream is gross, it’s also wondrous. Because when you sob, your nose is sobbing with you. And when you cry at a Hallmark commercial, you’re doing something uniquely human. Whether in joy or sorrow, your tears, visible signs of emotion, can’t be contained by your eyes. Your feelings are running out of your face through every available orifice.
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Writers may say “her eyes were brimming with tears,” but a healthy eye is brimming at all times. There are, in fact, three types of tears. The subtle basal tear—which is different from the ones I sob— comes from tiny glands under your eyelids, called the accessory lacrimal glands. These tears may taste like salty water, but really they are triple-layered complexes of water, salts, proteins, fats and hormones that produce a minorly-disgusting film that keeps the eye moist.
Basal tears sluice constantly over the eye, and pool in a place called the lacrimal lake, in the inside corner next to your nose. That lake has two tiny outlets, the lacrimal puncta, which you can see on the inside corners of your bottom and top eyelid. Those tiny holes drain through small channels to the nasolacrimal duct. As you can probably guess from the name, this duct drains right down into the nose. Basal tears usually go unnoticed, trickling down the back of the nose, swallowed at random.
The drama arrives with our other two types of tears, reflex tears and psychoemotional tears. These are the ones we notice, the ones that come pouring out of our eyes, and are produced by the main lacrimal gland (lacrima is the Latin word for tear), located on the upper, outside edge of the eye. Reflex tears help rid the eye of irritants—from the chemicals released when you chop onions to bits of sand or grit. Psychoemotional tears are the ones that emerge in response to emotion, from grief to shame to joy. In these cases, the lacrimal gland kicks into high gear, producing lots of watery tears, and leaving it to the nose to deal with the overflow.
Many animals have a reflex tear response. Yet emotional tears—even the ones dribbling out of your nose—are more than disgusting mixes of salt, water, proteins and hormones, formed into a slurry with your mucus. They are something that only humans seem to do.
People spend a lot of time asking what it is that makes us something “more” or “different” from other animals. Scientists have proposed many ideas that might have been the key to our world takeover, from bipedalism to language to tool use. But the more scientists learn about the world, the more our “superiorities” are shown to be false. Bipedalism and thumbs aren’t unique. Crows and primates make and use tools. Elephants and other highly social creatures take on long-term parental care. Animals exhibit social learning and complex social structures. Language may be one area where people are set apart, but whales, elephants, birds and other animals communicate in sophisticated ways. Even reflex tears are easily spotted in dogs or cats—as their remnants form the gross gunk doting pet parents wipe from their eyes.
Scientists love to float those reasons, but what about this one: Humans are the only species that weeps. Babies of many species have distress cries. But only humans pair those cries with tears and keep the skill as adults. We are the only species that has a big, open, gushing, response to emotion—whether our own or someone else’s. (Adult dogs can make distress cries, and a 2022 study suggested that they might well up a little when ecstatically reuniting with their owners, but other experts were skeptical about the results.)
No one truly knows why it is that humans cry with emotion, but one hypothesis is that our tears help us connect to each other. One study showed that adding tears to any emotional face made other people see the face as sadder. People are more likely to offer help when they see tears. Tears, flowing from our eyes and noses alike are displays of our emotions. They are also invitations. Invitations to other people to come and help. Invitations to join with us, to feel what we feel.
Tears are inherently vulnerable, which is part of what makes them an attachment behavior. They signal that we are feeling something strongly—that we might need something. Comfort, understanding, the simple presence of another person. They’re a reminder that we are intensely social creatures—that we derive our biggest strength from our emotional attachments to each other.
Perhaps previous generations of scientists clung on to tool use and thumbs to explain humanity because they appeared solid. Unemotional. There’s nothing vulnerable about tools. It can be uncomfortable to think that crying might be important—especially when most scientists are men, and women cry five times more often. Most of us have been told that crying is weak. For children. Illogical. But as I again sit on an airplane, bawling through the film Crazy Rich Asians, I might be at my most human. I’m dripping out of every hole in my face, and it’s because I’m emotionally connected to the people on my screen, feeling a tiny bit of what they feel. There is nothing more human than that.
This is an opinion and analysis article, and the views expressed by the author or authors are not necessarily those of Scientific American.
