Why do we cry, what are tears? Kids News explains

Crocodile tears are real – though humans are the only animals that cry emotional tears – and babies don’t cry tears at all.

These are just some of the fascinating facts Kids News discovered when we researched answers to the questions: Why do we cry? And: What are tears?

Here are some cool things to know about tears and crying.

YOU CRY THREE TYPES OF TEARS
Basal tears are constant tears, always in your eyes to keep them lubricated* and to wash out dust or other debris such as an insect.

Reflex tears form when there are irritants* such as smoke or fumes from onion in the air.

Emotional tears appear when you’re feeling emotional, such as happy or sad.

All tears are made in the lacrimal glands* above your eyeballs and are released through the tear ducts*. Blinking spreads the tears across the eye and surrounds, keeping everything moist and clean. When you have a big cry, the tears run down the back of your nose and mix with mucus*, making your nose run.

TEARS ARE SIMILAR TO SPIT
Tears are mostly water but also contain oils, salt (sodium), more than 1500 proteins, bicarbonate, chloride and potassium and tiny amounts of magnesium and calcium.

Each tear has three layers: mucus layer that keeps the tear attached to the eye, the aqueous* layer that keeps your eye wet and safe from bacteria and the oily layer, which keeps the other layers from evaporating and keeps the surface of the tear smooth so you can see through it.

TEARS ARE ENDLESS
Basal tear production can slow down with age, with some illnesses, when a woman is pregnant or from dust or staring at a computer screen.

This slowing down can lead to a condition called dry eye. Dry eye can make your eyes feel dry, itchy and scratchy but it can also make your eyes water.

You never actually run out of tears, no matter how much you cry. If you’re really crying hard, you could make half a cup of tears in just a few minutes.

IT COULD BE GOOD TO CRY
Scientists are still working on understanding why we cry emotional tears but many believe that it is a signal to others that you need help.

Some research has shown that other people can smell a signal that the crying person is in distress, even though tears don’t actually have any smell.

Other research has shown that emotional tears have slightly different ingredients – such as proteins and hormones* – to other types of tears that could have pain-relieving and relaxant* properties.

BABIES DON’T CRY TEARS
Newborn babies’ lacrimal glands — the glands that make tears — aren’t fully developed and so no tears come out when they cry.

Usually, babies are able to cry tears within a few weeks of birth. Occasionally, the ducts or holes where tears come into the eye are blocked at birth or soon after. Sometimes a block fixes itself and sometimes a doctor has to fix a blockage, but it’s nothing serious.

YOU CAN CRY IN YOUR SLEEP
Many people — more commonly babies and children — cry while they are sleeping or as they are waking up. This can happen because you’re having a bad dream, were upset when you were awake, are in pain, or because something is irritating your eyes.

CROCODILE TEARS ARE REAL
If someone says you’re crying crocodile tears, they mean you’re a hypocrite*, pretending to be upset and that the tears aren’t genuine.

It comes from an old story that crocodiles cry when they eat humans. This old story was mentioned in a book from 1400 called “The Voyage and Travel of Sir John Mandeville”.

Scientists now think that crocodiles may actually cry when they eat. Alligators and caimans — which are closely related to crocodiles — were observed in a study crying real tears when they were fed, though we don’t know why.

ANIMAL TEARS ARE NOT SAD TEARS
Animals cry tears to lubricate and clean their eyes like humans do.

But scientists are pretty much agreed that only humans cry to express emotion.

GLOSSARY

• lubricated: kept moist
• irritants: things that irritate
• glands: organs that make substances, such as sweat, tears, hormones
• ducts: pipe or tube
• mucus: slimy substance the body makes
• aqueous: made of water
• hormones: natural chemicals made by the body
• relaxant: something that relaxes something else
• hypocrite: a person who pretends to believe in one thing but acts another way

EXTRA READING

How and why do onions make us cry?

The mystery of the human belly button

All you need to know about hair

Celebrating World Emoji Day with tears of joy

QUICK QUIZ

1. What are the ingredients of tears?
2. Do tears have a smell?
3. What does a lacrimal gland do?
4. What does it mean to say you’re crying crocodile tears?
5. What is a caiman? Why is it in this story?

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. The book of tears
Create your own book all about tears:

1. Cut an A4 piece of paper in half. Place the two pieces one on top of the other. Fold the papers in half and staple on the folded side to make a book.
2. Create a front cover.
3. On each of the inside pages, in your own words, write down a fact that you found most interesting about tears. Draw a picture to match with each fact. (You should end up with 6 facts and illustrations.)

Time: allow 30 minutes to complete this activity 
Curriculum Links: English; Science

2. Extension
Write about a time that you cried emotional tears. Describe what happened and how you were feeling.

Time: allow 20 minutes to complete this activity 
Curriculum Links: English

VCOP ACTIVITY
After reading the article, with a partner, highlight all the openers you can find in blue. Discuss if they are powerful and varied openers or not. Why do you think the journalist has used a mix of simple and power openers? Would you change any, and why?

HAVE YOUR SAY: How often and why do you cry?
No one-word answers. Use full sentences to explain your thinking. No comments will be published until approved by editors.