Why Do We Cry Sad Tears?

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Hey smart people, Joe here.

How are you feeling today?

How are these definitely-not-generic-stock photo people feeling?

Are they neutral, ashamed, stoically handsome? Sometimes it can be a little hard to tell.

But if we add a few tears to these facial expressions, voila - these people look super

sad.

When we see faces get all contorted and messed up and liquid leaking out of eyeballs, that

sends a clear, unambiguous emotional message.

Because we are the only animal that cries.

Why?

[OPEN]

Pain.

Sorrow.

Dangerous foreign objects.

All of these things can make people cry.

This reaction makes sense when say, dust, gets into your eye, which always seems to

happen when I watch the beginning of Up.

[sigh pause thought bubble scene] You make tears to flush your eye clean.

But what’s the point of making tears when were sad?

Why did humans evolve emotional crying?

We make a few kinds of tears.

Tears of sadness are called emotional or psychic tears.

They differ from reflex tears, which we make to flush our eyes in response to irritants.

We even make a third type of tear, basal tears: a liquid force-field were constantly producing

to protect and lubricate our eyes.

Each tear type has a different recipe.

All three contain salt, proteins, and antibacterial enzymes, but emotional tears have higher amounts

of protein, including stress hormones and natural painkillers that we don’t yet know

the purpose of.

And while all three are secreted from the lacrimal glands in your eye, only the production

of emotional tears is controlled by the hypothalamus - an area of your brain that regulates emotional

responses.

Across cultures, aside from speaking, humans communicate with each other in many ways:

through gestures, posture, even touch.

But we tend to read other people’s emotions through their face.

We have over 40 muscles in our face alone, capable of deforming our appearance in a number

of very weird ways.

Like blushing, laughing, and teenage eye-rolling, before we had language, it’s possible tears

evolved as a way to send a message to people close to us that we were experiencing strong

emotions.

Individuals that could clearly and reliably communicate sadness were more likely to receive

help, which increased the likelihood they would survive and reproduce.

We can’t know for sure, but it makes evolutionary sense.

And so do crying babies.

A baby can’t tell you that theyre hungry, tired, or uncomfortable, because they can’t

talk, so tears are effective baby communication.

But humans keep crying into adulthood.

Adults don’t cry with as much noise as babies do, THANKFULLYcan you imagine?

But our grown up eyes still shed tears.

Studies show that most people that see tears, want to help.

That’s because, while evolving tears, we also evolved a response to them: feelings

of empathy or sympathy.

We tend to see a crying person as helpless and feel more connected to them.

These feelings likely helped us develop social bonds.

That innate response is why you probably felt different when we added tears to these pictures.

Lots of animals make tears, but as far as we know, were the only animals to cry emotional

tears.

Other animals have distinct facial expressions to communicate fear or pain, but no other

species that we know of has a sad signal quite like tears.

It’s true we also cry at happy things, and scientists don’t exactly know why.

Perhaps were just plain overwhelmed with emotions.

Or it could be that youre actually crying at the sad part of the thing, like how weddings

and graduations signify the end of something, or when youre happy to see someone because

you missed them so much.

There’s a lot we still don’t know about crying, but it’s clear that it’s one of

the most human things we do.

Why didn’t they get one more adventure together.

Stay Curious.