HUMAN BODY

The squishy, spinning, signal-firing machine you live inside every day.

50 facts

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Humans actually glow in the dark - too faintly for us to see.

RECORD-BREAKERS

Humans actually glow in the dark - too faintly for us to see.

Our bodies emit tiny amounts of light, around 1,000 times dimmer than what our eyes can detect.

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MORE HUMAN BODY FACTS

49 facts

No two people have the same fingerprints - not even identical twins.

DID YOU KNOW? No two people have the same fingerprints - not even identical twins. Your fingerprints are shaped while you're still in the womb. 2 min read

Muscle memory is real - but it's actually in your brain.

DID YOU KNOW? Muscle memory is real - but it's actually in your brain. With enough practice, your brain wires up a "shortcut" so you don't have to think. 2 min read

White blood cells are your immune army.

DID YOU KNOW? White blood cells are your immune army. They hunt down germs and learn what to attack next time. 2 min read

Most of your body gets replaced over many years.

DID YOU KNOW? Most of your body gets replaced over many years. Cell by cell, your body is constantly rebuilding itself - though some parts stay with you for life. 2 min read

Blue eyes don't actually contain any blue pigment.

DID YOU KNOW? Blue eyes don't actually contain any blue pigment. They look blue the same way the sky does - by scattering light. 2 min read

Your deepest sleep makes you almost impossible to wake up.

DID YOU KNOW? Your deepest sleep makes you almost impossible to wake up. The N3 sleep stage is when your brain is barely responding to the outside world. 2 min read

The longest hair ever recorded was over 18 feet long.

DID YOU KNOW? The longest hair ever recorded was over 18 feet long. Xie Qiuping of China grew her hair for 31 years without cutting it. 2 min read

A baby's heart beats almost twice as fast as an adult's.

DID YOU KNOW? A baby's heart beats almost twice as fast as an adult's. Newborns clock in around 140 bpm - and slow down as they grow. 2 min read

Your smallest blood vessels are narrower than a hair.

DID YOU KNOW? Your smallest blood vessels are narrower than a hair. Capillaries are so thin that red blood cells pass through them single-file. 2 min read

The tallest person ever was almost 9 feet tall.

DID YOU KNOW? The tallest person ever was almost 9 feet tall. Robert Wadlow grew 8 feet 11 inches and was still growing when he died at 22. 2 min read

The oldest person in verified history lived to 122.

DID YOU KNOW? The oldest person in verified history lived to 122. Jeanne Calment of France was born in 1875 and died in 1997. 2 min read

The longest cell in your body stretches from your spine to your toe.

DID YOU KNOW? The longest cell in your body stretches from your spine to your toe. Some motor neurons are up to 4 feet long - just one cell. 2 min read

Your skin is the largest organ in your body.

DID YOU KNOW? Your skin is the largest organ in your body. An adult's skin would cover about 22 square feet - and weighs around 8 pounds. 2 min read

Your "funny bone" isn't actually a bone.

DID YOU KNOW? Your "funny bone" isn't actually a bone. It's a nerve right under the skin - and hitting it is anything but funny. 2 min read

Your heart beats about 100,000 times every day.

DID YOU KNOW? Your heart beats about 100,000 times every day. That's roughly 2.5 billion beats over an average lifetime. 2 min read

Your tongue is made of eight muscles working together.

DID YOU KNOW? Your tongue is made of eight muscles working together. Half of those muscles aren't attached to any bone at all. 2 min read

You have three completely different kinds of muscle.

DID YOU KNOW? You have three completely different kinds of muscle. Skeletal moves your bones, smooth runs your gut, cardiac never stops. 2 min read

Bones are alive - they're constantly remodeling themselves.

DID YOU KNOW? Bones are alive - they're constantly remodeling themselves. You're slowly replacing your entire skeleton over and over. 2 min read

Your thigh bone is so strong it's harder than concrete.

DID YOU KNOW? Your thigh bone is so strong it's harder than concrete. The femur can support hundreds of pounds of pressure without breaking. 2 min read

The smallest bone in your body is the size of a grain of rice.

DID YOU KNOW? The smallest bone in your body is the size of a grain of rice. It sits deep inside your ear, transmitting every sound you hear. 2 min read

Adults have 206 bones - but babies have over 300.

DID YOU KNOW? Adults have 206 bones - but babies have over 300. As you grow up, some of your bones fuse together. 2 min read

Your bones are constantly making fresh blood.

DID YOU KNOW? Your bones are constantly making fresh blood. Deep inside them, bone marrow churns out millions of blood cells every second. 2 min read

Most of your brain cells stay with you for life.

DID YOU KNOW? Most of your brain cells stay with you for life. Unlike skin or blood, neurons mostly don't get replaced. 2 min read

Every one of your cells has hundreds of tiny power plants.

DID YOU KNOW? Every one of your cells has hundreds of tiny power plants. They're called mitochondria - and they have their own DNA. 2 min read

Stem cells can become almost any other kind of cell.

DID YOU KNOW? Stem cells can become almost any other kind of cell. They're the body's blank-slate cells - and we're learning to use them to heal. 2 min read

Cancer is what happens when cells stop knowing when to stop dividing.

DID YOU KNOW? Cancer is what happens when cells stop knowing when to stop dividing. They keep splitting, building up into clumps that don't belong there. 2 min read

All your cells came from a single cell that kept splitting.

DID YOU KNOW? All your cells came from a single cell that kept splitting. Mitosis turns one cell into two, two into four, four into eight - and so on. 2 min read

Red blood cells have no nucleus - they're essentially empty oxygen buckets.

DID YOU KNOW? Red blood cells have no nucleus - they're essentially empty oxygen buckets. They give up their DNA at birth to make more room for oxygen. 2 min read

Some people see colors when they hear music.

DID YOU KNOW? Some people see colors when they hear music. It's called synesthesia - and about 1 in 25 people experience it. 2 min read

"Touch" is actually four senses combined.

DID YOU KNOW? "Touch" is actually four senses combined. Pressure, vibration, temperature, and pain each have their own receptors. 2 min read

You blink 15-20 times every minute - totally automatically.

DID YOU KNOW? You blink 15-20 times every minute - totally automatically. That's enough that your eyes are closed for about 10% of your waking hours. 2 min read

You have a sixth sense - it tells you where your body is.

DID YOU KNOW? You have a sixth sense - it tells you where your body is. Close your eyes and touch your nose. That's proprioception working. 2 min read

Pain isn't a sense - it's a decision your brain makes.

DID YOU KNOW? Pain isn't a sense - it's a decision your brain makes. Your brain weighs danger signals and decides what gets to hurt. 2 min read

You see color using just three types of cells.

DID YOU KNOW? You see color using just three types of cells. All the colors you'll ever see come from three flavors of cone cells in your eye. 2 min read

You hear with tiny hair cells deep in your ear.

DID YOU KNOW? You hear with tiny hair cells deep in your ear. They turn vibrations from the air into electrical signals your brain can read. 2 min read

Your tongue can taste five things - not four.

DID YOU KNOW? Your tongue can taste five things - not four. Sweet, sour, salty, bitter, and umami (the savory taste of soup or cheese). 2 min read

Your brain runs on tiny electrical signals.

DID YOU KNOW? Your brain runs on tiny electrical signals. Each neuron fires a pulse hundreds of times per second. 2 min read

Memory isn't one thing - your brain has several different memory systems.

DID YOU KNOW? Memory isn't one thing - your brain has several different memory systems. Where your house is, how to ride a bike, and a phone number all use different parts. 2 min read

Your brain runs almost entirely on sugar.

DID YOU KNOW? Your brain runs almost entirely on sugar. Glucose is basically the only fuel it'll accept. 2 min read

A baby's brain has more neurons than an adult's.

DID YOU KNOW? A baby's brain has more neurons than an adult's. As you grow up, your brain trims away the connections you don't use. 2 min read

Nobody can actually multitask - the brain just switches really fast.

DID YOU KNOW? Nobody can actually multitask - the brain just switches really fast. What feels like doing two things at once is actually a tiny mental relay race. 2 min read

Your brain has two halves that don't fully agree on everything.

DID YOU KNOW? Your brain has two halves that don't fully agree on everything. The left side controls the right side of your body - and vice versa. 2 min read

Your brain feels no pain - but it's what makes everything else hurt.

DID YOU KNOW? Your brain feels no pain - but it's what makes everything else hurt. Surgeons can operate on a brain while the patient is awake and chatting. 2 min read

We dream most vividly during REM sleep - when our eyes move under our eyelids.

DID YOU KNOW? We dream most vividly during REM sleep - when our eyes move under our eyelids. Your body becomes temporarily paralyzed so you don't act out the dream. 2 min read

Your brain has about 86 billion neurons.

DID YOU KNOW? Your brain has about 86 billion neurons. That's roughly the number of stars in the entire Milky Way galaxy. 2 min read

Your brain uses 20% of your body's energy - even when you're resting.

DID YOU KNOW? Your brain uses 20% of your body's energy - even when you're resting. It's only 2% of your weight but burns one fifth of all your fuel. 2 min read

The strongest muscle for its size is in your jaw.

DID YOU KNOW? The strongest muscle for its size is in your jaw. The masseter - the muscle that closes your bite - can apply over 200 pounds of force. 2 min read

Your nose can remember about 50,000 different smells.

DID YOU KNOW? Your nose can remember about 50,000 different smells. A single whiff can throw you back to a memory you forgot you had. 2 min read

Your body makes about 4 million new cells every single second.

DID YOU KNOW? Your body makes about 4 million new cells every single second. That's roughly 330 billion brand-new cells every day - replacing the ones you lost. 2 min read

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