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  • - The first thing you did in this world was cry.

  • What does it say about the human condition

  • that when you enter this world crying,

  • the doctor's like,

  • the baby's emotionally devastated to be here, check.

  • Humans are the only animals

  • that produce tears due to emotion.

  • Elephants, for example, produce tears,

  • but mostly due to irritation.

  • In fact, the lobocraspis griseifusa moth

  • will irritate an elephant's eye

  • so it produces tears that it can drink.

  • Imagine asking a kid what their favorite animal was

  • and they were like, Oh you know,

  • the moth that irritates elephant's eyes

  • in order to drink their tears.

  • I'd be like, okay, this kid, he's got issues.

  • You on the other hand could produce tears from a loss,

  • joy, self-pity, laughter or when the tone switches

  • in a "That's So Raven" episode.

  • And tis wild, but the chemical makeup of your tears

  • changes based on your emotions.

  • So why are human tears so unique?

  • Tears of endogenous depression are different

  • than tears from acute grief.

  • If you remove the tears from crying people's faces,

  • it's hard for you to tell if they're crying from sadness

  • or laughing from pure joy.

  • Scientists have a hard time studying tears,

  • especially emotional ones.

  • A lot of these studies involve humans as lab rats,

  • watching sad movies and studying their crying behavior.

  • Or there are morbid studies.

  • For example, the one on brain dead people,

  • where they found they produce tears

  • when their organs are removed

  • and will slightly open their eyes

  • when their nipple is twisted.

  • For this next study,

  • could you twist that brain dead person's nipple, please?

  • (laughing) Do not kill the messenger.

  • I did not twist those nipples a scientist did.

  • Oh, they opened their eyes slightly, fascinating.

  • Due to recent scientific insight

  • we know a lot more about why we emotionally cry.

  • Back in 17th century America for example,

  • it was thought that a marriage was doomed

  • if the bride did not profusely weep at the wedding.

  • This was to prove the bride wasn't a witch,

  • as witches were known to cry

  • only three tears from the left eye.

  • Therefore obviously the bride was crying from both eyes

  • it meant that the bride was not working with Satan.

  • Think of all the groomzillas who were like,

  • she's ruining my perfect day,

  • she's not crying from both eyes.

  • Thine is a witch

  • honestly straight weddings are like, so over the top.

  • To know why you as a human cry,

  • you have to think back millions of years

  • to when your ancestors evolved out of the water.

  • Yep. Your great, great, great

  • times a million million grandparent

  • looked like some sort of insect-y shell

  • amphibian arthropod millipede sort of thing, maybe.

  • And by leaving the water to live on land,

  • all of these land dwelling animals from then on

  • needed a lacrimal apparatus to produce tears

  • that kept the eyes wet while on land.

  • But you, my friend are special

  • because you have three types of tears.

  • The first is basal tears, which is made up of three layers.

  • A mucus layer that touches the eyeball,

  • an aqueous layer, which moisturizes

  • and protects against invasive bacteria,

  • and the final oily layer

  • that stops the other layers from evaporating

  • and keeps the surface of the eyes smooth.

  • So your vision is clear.

  • The second is reflex tears,

  • which is unique to all land dwelling animals.

  • In fact, all animals, except for snakes and amphibians,

  • have a peripheral sensory system

  • that consists of nerve endings in the eye

  • that when stimulated by mechanical, thermal, chemical,

  • or pain stimulus release tears.

  • It should be known that you don't have a storage of tears

  • in your eye, ready to come out when you cry,

  • the tears are created due to a sensory in your body

  • that triggers the response.

  • Humans, that means me, that means you are special.

  • We are the only animals with emotional tears,

  • also known as psychogenic tears.

  • Which are controlled by the prefrontal cortex

  • and the anterior portion of the limbic lobe of the brain.

  • Some scientists think that we cry

  • because as a child,

  • crying was the only way that we were able

  • to get a response from our parents.

  • As babies, we don't have the words to express our feelings,

  • so crying is what we do, and it works.

  • Known as the acoustic umbilical cord.

  • Crying serves to connect the infant to the caregiver

  • as an adaptive strategy.

  • Developmental psychologists believe

  • that crying enhances infant survival

  • by eliciting care and protection from caregivers.

  • In lactating, females infant crying can cause a rise

  • in breast temperature and a milk let down reflex.

  • But the crying starts to decrease

  • at a time of for brain development in the baby.

  • When the baby is 24 months old

  • concurrent with rapid development of spoken language,

  • crying seems to fall off.

  • Because of this research,

  • some scientists posit that we cry

  • when we don't have the words to explain how we're feeling.

  • Which I can relate to.

  • I feel like when I cry, it's usually in moments

  • where I don't have the words to express

  • what I'm feeling.

  • Much like when I was a kid, crying for my mom's attention,

  • when I couldn't speak English.

  • It feels like now when I cry it's when emotions are so big

  • I don't really know how to explain them.

  • Whether they're happy or sad.

  • And crying, it's showstopping.

  • If you cry at a party,

  • people are going to pay attention to you.

  • I have a hard time

  • when the attention is on me in public settings,

  • so I really like to cry alone while watching a movie.

  • In fact, once my mom almost kicked me out of a movie theater

  • because I was crying so loud during "Ever After"

  • that the people in the audience were like, please be quiet.

  • We can't even focus on the movie.

  • Emotional tears are really cool.

  • But it turns out that the chemical makeup of tears

  • from emotion are different than the tears from irritation.

  • A study found that the protein concentration

  • of emotional tears was 24% greater

  • than that of an irritant,

  • and the higher protein tears fall more slowly on the face.

  • Some scientists think

  • that emotional tears evolve to have more proteins in them

  • causing them to fall slower

  • and give more time for our fellow humans to react

  • to the response and give us an emotional boost.

  • In fact, using eye tracking,

  • a new study found that humans focus way more

  • on faces with tears and are more aroused by them.

  • The visual image of a tear falling down a cheek

  • sets off a response in us to help and be interested.

  • This all leads to the predictions

  • that human emotional crying

  • is a way to get other people to look at you.

  • The higher protein concentration of emotional tears

  • makes them fall more slowly,

  • so people will pay attention and look after you.

  • There is no gender difference

  • in crying frequency in infants,

  • but there is a big shift when we get to adulthood.

  • In a sample of 286 women and 45 men

  • between the ages of 18 to 75,

  • it was found an average

  • of 5.3 crying episodes per month for the women.

  • And 1.4 crying episodes per month for the men.

  • For the women,

  • most of the cries had to do with a sad film or TV show.

  • In fact, studies show that from 11 to 16 years of age,

  • boys cry more from physical pain.

  • Whereas girls cry more for empathetic reasons,

  • especially during movies again, or TV shows.

  • This led some other studies to posit

  • that women are more empathetic to the crying of others

  • and found they're more likely

  • to stop and help someone crying on the street.