Why do we cry?

Leviathan Press:

If you are a person who wears glasses like me, maybe next time you can pay attention to what is left on the lenses after you shed tears: you will find that there are jet-like tear marks on the lenses near the tear points. At this time, I feel that the word "tears" is so vivid.

I cry on planes all the time, for no particular reason. Just the other day, I broke down in tears while immersed in Emily Henry’s Book Lovers at 30,000 feet. I’ve never been a gentle, mellow cryer: my whole body contorted as I tried to hide my breathless, lung-rending sobs.

The humiliation of having to ask the flight attendant for more tissues in the small public space after using up the measly tissues reinforced the fact that a good cry is never as simple as tears flowing down your shiny cheeks. Yes, your eyes are red and puffy, and your nose is still running. Not the thick mucus of the late stages of a cold, but thin, white streams flowing into your mouth.

It's disgusting, but also fascinating, because when you cry, your nose cries along with you. When you cry at an ad, you're doing something uniquely human: Your tears, the visible sign of emotion, whether joy or sadness, can't be contained by your eyes. Your feelings are pouring out of your face through every available orifice. A writer might say "her eyes were full of tears," but healthy eyes are full of tears all the time.

© Abdominal Key

There are actually three types of tears. Delicate basal tears (not the same as the tears I cry) come from tiny glands under my eyelids called accessory lacrimal glands. These tears may taste a bit salty, but they're actually a three-layered complex of water, salts, proteins, lipids, and hormones that create a slightly disgusting film to keep your eyes moist.

The arrow shows the tear punctum on the lower eyelid. © Carlisle Vision Care

Basal tears flow continuously through the eye and collect in a place called the lacrimal lake at the inner canthus near the nose. This lake has two tiny holes, the puncta, which you can see on the lower and upper eyelids near the inner canthus. These holes drain through a channel to the nasolacrimal duct.

As you might guess from the name, this duct drains directly into the nose. Basal tears usually go unnoticed, running down the back of the nose and being swallowed at will. The drama occurs with our other two types of tears – reflex tears and psychoemotional tears .

These tears, which well up from our eyes, are produced by the lacrimal gland (lacrima is Latin for "tear"), located on the upper, outer edge of the eye. Reflex tears help clear irritants from the eye -- like chemicals released by cutting onions or grit. Psychoemotional tears are responses to emotions, from sadness to shame to joy.

In these situations, the tear glands kick into high gear, producing large amounts of watery tears, which are then sent to the nose to process the overflow. Many animals have a reflex tear response. However, emotional tears - even those that come out of your nose - are not just salt, water, proteins and hormones mixed with your snot to form a paste. They seem to be something that only humans produce. People have spent a lot of time discussing what makes us "different" from other animals.

Scientists have proposed many ideas that may be the key to our dominance, from walking upright to language to using tools. But the more scientists learn about the world, the more spurious our “superiority” seems. Walking upright and having thumbs are not unique to humans; ravens and primates also make and use tools[1], and elephants and other highly social animals perform long-term parental care.

In general, animals exhibit social learning and complex social structures[2]. Language may be one area where humans are unique, but whales, elephants, birds, and other animals also communicate in complex ways. Even reflex tears are easy to spot in dogs or cats.

© Timothy A. Clary/AFP via Getty Images

Scientists love to come up with these reasons, but here's one: Humans are the only species that can cry. Many species have babies that make sad cries. But only humans associate crying with tears and retain that skill as adults.

We are the only species that has an intense, open, gushing response to emotions, both our own and others’. (Adult dogs can produce sad cries, and a 2022 study suggests[3] that they may shed tears when they are overjoyed to be reunited with their owners, but some experts are skeptical of these results.) No one really knows why humans cry in response to emotion, but one hypothesis is that our tears help us connect with one another[4].

One study[5] showed that adding tears to any emotional face made other people perceive that face as sadder. When people see tears, they are more likely to offer help. Tears flow from our eyes and noses, signaling our emotions. They are also an invitation: an invitation for others to come and help. An invitation to join us and experience our feelings. Tears are inherently vulnerable, which is part of what makes them an attachment behavior.

© Gifer

It strongly suggests that we may need some kind of support, comfort and understanding, or simply the presence of another person. Tears also remind us that we are highly social creatures - we gain our greatest strength from emotional attachment to each other. Perhaps the reason why scientists in the past have always looked to tool use and thumbs as explanations of human characteristics is because they seem more objective and rational.

Tool use is not emotional. The idea that crying might be important might make some people uncomfortable, especially given that most scientists are men and that women cry five times more often than men. Most of us have been taught that crying is weak, childish, and illogical. But as I sat on a plane again, watching the movie Crazy Rich Asians, and felt the sadness come over me, I was probably at my most human.

Tears welled up in my eyes, tears flowed from every pore of my face, because I connected emotionally with the people on the screen - there is no more human moment than this.

By Bethany Brookshire

Tempura

Proofreading/Rabbit's Light Footsteps

Original article/www.scientificamerican.com/article/the-evolution-of-a-big-ugly-cry/

This article is based on the Creative Commons License (BY-NC) and is published by Tempura on Leviathan

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