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Transcript
00:00:00 Wow, just one strand of hair can support about 3 ounces.
00:00:04 On average, a person has about 150,000 strands, and when your hair is working as a team, it
00:00:10 can support about 12 tons!
00:00:12 That's two elephants!
00:00:14 Not counting the peanuts.
00:00:16 Your brain generates electricity, and it'd be enough to light up a small light bulb…if
00:00:21 you could only figure out how.
00:00:23 It doesn't hurt to cut your nails or hair, because the only part that's alive is under
00:00:28 the skin.
00:00:29 Also, nails grow faster in summer than in winter, even in places where there's not
00:00:33 much difference between the seasons.
00:00:36 Also, nails grow faster on your writing hand, probably because you use it more often and
00:00:41 that stimulates the nails more.
00:00:43 It looks like the pinky finger is weak, but that's not true at all.
00:00:47 Without it, you'd lose 50% of your hand strength.
00:00:50 It usually works together with your ring finger to provide power.
00:00:54 The other three are more for grabbing stuff.
00:00:57 Oh, and just like fingerprints, your tongue has a unique print too.
00:01:01 But you can't use it to unlock your phone, at least not yet.
00:01:05 Also, your tongue has a lot of fat in it.
00:01:08 If you gain weight, your tongue does too.
00:01:11 There's acid in your stomach that breaks down food.
00:01:15 The acid is so strong that it could eat right through a piece of wood.
00:01:19 The total length of all blood vessels in an adult is close to 100,000 miles!
00:01:24 That's 4 times around the equator!
00:01:27 In your lifetime, you produce enough saliva to fill two swimming pools.
00:01:33 Our ancestors needed goose bumps to make their body hair stand on end and scare away any
00:01:37 bad guys.
00:01:39 We don't need that anymore, but we still get them because we haven't evolved enough
00:01:43 yet to get rid of this feature.
00:01:45 Now you probably never noticed, but you mostly only breathe through one nostril at a time.
00:01:51 Every few hours, the nostrils switch jobs.
00:01:53 That's why only one nostril gets stuffy when you have the flu.
00:01:58 Most people think they have 5 senses, but that's not true.
00:02:02 Scientists don't yet know themselves, but they think there's more than 20.
00:02:06 There's sight, hearing, touch, smell, and taste.
00:02:09 And there are other senses like time, hunger, and thirst.
00:02:13 Then there's proprioception, the sense of where your body is in space.
00:02:19 The brain can't always tell the difference between intense happiness and intense sadness.
00:02:24 It gets that you're experiencing a very strong emotion, but sometimes it gets a bit
00:02:29 confused.
00:02:30 That's why you might cry when you're very happy.
00:02:33 Your eyes stay about the same size your whole life, but your nose and ears don't.
00:02:38 That'd be so weird.
00:02:40 Back in the day, all humans had brown eyes.
00:02:43 Other eye colors developed as a result of a random mutation.
00:02:47 Scientists think that while the first humans appeared on Earth around 6 million years ago,
00:02:52 the first blue-eyed person appeared only 10,000 years ago.
00:02:56 So it's pretty likely that all blue-eyed people on the planet have the same ancestor.
00:03:02 Uncle Bob!
00:03:04 All bones in the human body are connected to each other except one.
00:03:08 The hyoid bone is U-shaped and located at the base of the tongue holding it in place.
00:03:15 Bones are stronger than steel.
00:03:17 A strong healthy bone could, in theory, handle the weight of 5 pickup trucks.
00:03:22 Still, they're not the strongest body part.
00:03:25 The strongest is tooth enamel.
00:03:27 It's made of a bunch of different materials that make it damage-resistant.
00:03:32 Teeth live a long time, lasting for hundreds of years.
00:03:35 But of course, you still need to take care of them.
00:03:38 They're the only body part that can't heal itself.
00:03:42 Your heart works non-stop and beats around 3 billion times over the course of your lifetime.
00:03:49 Just like your heart, your tongue never takes a vacation.
00:03:52 Even when you sleep, it helps push saliva down your throat.
00:03:56 By the way, where do you rest your tongue?
00:03:59 If you keep it on the bottom of your mouth, you're doing it wrong.
00:04:02 This posture might lead to some neck and jaw pain.
00:04:05 If you keep it jammed up against your teeth, you're doing it wrong too.
00:04:09 It can cause your teeth to shift and might lead to a bad bite.
00:04:13 Instead, try to keep it sort of halfway, about a half an inch away from your teeth.
00:04:19 We can't breathe and swallow at the same time.
00:04:22 That's because whatever we swallow and the air we breathe travel down the same path,
00:04:27 at least at first.
00:04:28 It's like there's a little guy directing traffic down there.
00:04:32 Your eyes can breathe.
00:04:33 The cornea is the only body part that doesn't have a direct blood supply.
00:04:38 It gets oxygen right from the air.
00:04:40 That's why when it's dry outside, your eyes might get a bit itchy.
00:04:46 Everyone dreams.
00:04:47 Some people say they've never dreamt a night in their life, but they just never remember
00:04:51 any of their dreams.
00:04:53 Some scientists think that the dreaming stage is followed by an active forgetting stage.
00:04:58 It's probably because dreams aren't exactly full of important information, and our brain
00:05:03 needs to clean up some extra space for something more useful.
00:05:08 Those who are lucky enough to remember their dreams still end up forgetting about half
00:05:12 within 5 minutes of waking up, and after 10 minutes, it's usually gone for good.
00:05:18 When you blush, the lining of your stomach turns red too.
00:05:22 It happens because blood starts to flow around more when you're embarrassed, as your body
00:05:27 gets ready for something stressful to happen.
00:05:30 Your face and stomach lining get more of it, turning them red.
00:05:33 Also, humans are the only animals who can blush, or at least the only ones where you
00:05:38 can see it so obviously.
00:05:41 During one lifetime, the average human grows 590 miles of hair.
00:05:46 The average man, if he never shaved, would have a 30-foot-long beard.
00:05:51 Hair grows a little faster in warm climates because heat stimulates faster circulation
00:05:55 in our bodies.
00:05:57 Everything you'd ever need to know about you is all written down in one strand of hair.
00:06:02 From a single hair, a scientist could tell you what you've been eating your whole life
00:06:07 and what kind of environment you've lived in.
00:06:09 On average, one human eats their way through 100,000 pounds of food in one lifetime.
00:06:15 That's like 10 big hippos worth of food!
00:06:19 Lips are one of the most sensitive parts of the human body.
00:06:22 They have loads of nerve endings, even more than your fingers.
00:06:25 Also, lip skin is very thin, so you can actually see the blood capillaries inside.
00:06:31 That's why lips are red or pink, unlike the rest of your body.
00:06:35 Lips are also very sensitive to sun damage, so remember to apply sunscreen on them.
00:06:40 It'll help to preserve their health and fullness over time.
00:06:45 In addition to your fingerprints, your iris, and your tongue, your lips are also unique.
00:06:51 The total surface of your lungs is about the same as a tennis court.
00:06:55 Coughs and sneezes are real fast travelers.
00:06:58 A cough can get up to 50 mph, a sneeze is even faster – almost 100 mph!
00:07:06 Unless you use your fingers to help you, it's impossible to sneeze with your eyes open.
00:07:11 Scientists don't really know what's going on there.
00:07:13 Some say it's just a reflex, so you can't control it.
00:07:17 Others think it happens to shield your eyes from whatever's flying out.
00:07:21 All humans literally glow.
00:07:24 The light comes from your body heat.
00:07:26 It's actually a thousand times less intense than you're capable of seeing, but still
00:07:30 awesome!
00:07:33 The largest flash drive in the world is actually your brain.
00:07:36 Well, anyone's brain.
00:07:38 The neurons in it combine together in such a way that your storage capacity is about
00:07:43 a million gigabytes.
00:07:45 It's enough to hold 3 million hours of movies.
00:07:48 That's like a 300-year-long movie night!
00:07:51 Hey, pass the popcorn!
00:07:53 You start feeling thirsty when you lose about 1% of your body weight.
00:07:58 If you lose 5%, you might even feel like fainting.
00:08:02 Fingers don't have muscles that make them move.
00:08:04 The muscles that do that are located in the palm and the forearm.
00:08:09 The word "muscle" actually comes from the old Latin word for "mouse."
00:08:13 That's what the Romans thought their biceps looked like.
00:08:16 On average, in their lifetime, a person walks about 110,000 miles.
00:08:21 That's 4 times the distance around our planet, or half the distance from the Earth to the
00:08:26 Moon.
00:08:27 So, remember to wear comfortable shoes!
00:08:35 It takes about a month for all the skin cells to renew.
00:08:39 We shed about 30,000 dead cells every 60 seconds, losing about 9 pounds of skin every year.
00:08:46 So when your friends call you "flaky," they're not entirely wrong.
00:08:50 Their fingernails grow way faster than toenails.
00:08:53 The latter grow almost 4 times slower because they're less frequently damaged than fingernails.
00:08:59 Even though we often stumble on them, sudden circulation bursts usually don't last long.
00:09:04 An eyelash is only here to stay for 150 days.
00:09:08 The world eyelash record was about 3 inches long.
00:09:12 They're also home for tiny mites.
00:09:14 We blink about 4,200,000 times a year, at least once every 8 seconds.
00:09:20 When we sneeze, the air that we blow speeds out at 100 mph.
00:09:25 It could accelerate faster than a brand-new Ferrari.
00:09:28 Also, you could fracture a rib if you sneeze too hard.
00:09:33 Depending on the person, a human produces from half a quart to a full quart of saliva
00:09:38 every single day.
00:09:40 That's enough saliva to fill several bathtubs in a year.
00:09:43 No spit!
00:09:45 Saliva acts as a perfect remedy.
00:09:47 Wounds in our mouth heal way faster than elsewhere.
00:09:50 It also helps to taste food.
00:09:52 Our taste buds are ready to perceive it only when it's dissolved in saliva.
00:09:57 It may sound crazy, but our bones are stronger than they seem.
00:10:00 A cubic inch of human bone can bear about 19,000 pounds, making it 4 times stronger
00:10:06 than concrete.
00:10:08 The only thing that makes our blood type different is sugar.
00:10:11 AB and AB types have 5 types of sugars, while O has only 4, which makes it perfect for donors.
00:10:19 Lack of additional sugar doesn't make O type less sweet.
00:10:23 In fact, it attracts mosquitoes even more than other blood types.
00:10:27 People have only 8 blood types, while cows have 800 and possibly more.
00:10:34 Usually we shed about 50 to 150 hairs a day.
00:10:37 An average lifespan of a hair is 5 years, and as soon as an old hair says goodbye to
00:10:43 your scalp, a new one starts growing immediately.
00:10:46 A human hair is stronger than the same diameter copper wire.
00:10:50 A single hair can hold up to 3.4 ounces of weight, and if used properly, a full head
00:10:56 can hold up to 18,500 pounds.
00:11:00 Our stomach is bigger than it may seem with a capacity of nearly half a pound when needed,
00:11:05 while the average is around 32 ounces.
00:11:08 The food is digested within 4 to 6 hours, and it can also dissolve metal, so capacity
00:11:14 matters.
00:11:15 Lips are much more sensitive than fingers, having around a million nerve endings.
00:11:20 They are 100 times as sensitive as the tips of fingers.
00:11:25 Grooves and furrows make our lip print unique, just like fingerprints are.
00:11:29 They also remain unchanged throughout our life.
00:11:33 Tongue print is unique too, by the way.
00:11:35 So when are we gonna see a tongue print reader?
00:11:38 Our belly buttons have an entire zoo in them, with a range of about 70 different bacteria.
00:11:44 Some of them can also be found in soil in Japan, and even several kinds of bacteria
00:11:48 typical for polar ice caps.
00:11:51 Our bodies actually glow.
00:11:53 We can't see that with the naked eye though, because the light we emit is 1,000 times less
00:11:58 intense than the minimum level we can perceive.
00:12:02 Humans are the only living things on Earth that can actually blush, or need to, according
00:12:07 to Mark Twain.
00:12:09 Blushing is provoked by an adrenaline rush.
00:12:12 Carmine, used in blushes and lipsticks, is red dye made up of ground-up beetles.
00:12:18 Ew!
00:12:19 Your ears keep growing throughout your life.
00:12:21 They do sweat too, and earwax is actually the kind of sweat they produce.
00:12:27 By the way, your nose never stops growing either.
00:12:31 Your heart is the only muscle that never gets tired.
00:12:34 The aorta is massive.
00:12:36 Its diameter is almost as large as a hose in your garden.
00:12:41 We emit about 16 to 48 ounces of gases every day, which is enough to fill a small balloon.
00:12:47 Okay, you can insert the appropriate sound effect here.
00:12:51 Good job!
00:12:53 Fat helps our bodies consume vitamins.
00:12:56 Such vitamins as A, D, K, and E can be properly absorbed only when they're dissolved in fat.
00:13:03 Our bodies have enough fat to produce 7 bars of soap.
00:13:07 Fat heads made of sebum aren't black because they're dirty.
00:13:11 They get dark because the debris is oxidized.
00:13:14 Some parts of your brain can eat up their own neurons and proteins if you don't provide
00:13:19 enough sleep.
00:13:20 For example, the hypothalamus that's responsible for your sleep, hunger, and body temperature
00:13:25 can do that.
00:13:27 You can't inhale and swallow at the same time.
00:13:30 I know you've just tried it.
00:13:32 The thing called the pharynx is used as an air passage when you inhale or as a food passage
00:13:38 when you swallow.
00:13:40 When we're awake, our brain may produce enough energy to turn an electric bulb on.
00:13:45 It generates about 10 watts of power.
00:13:48 You carry enough bacteria in your body to fill a can.
00:13:53 Bacteria make about 3 to 5 pounds of your weight, representing 2% of our total weight.
00:13:58 Still, most of them are the waste that our body has.
00:14:02 The normal body temperature is considered to be at a range of 97 to 99°F. The highest
00:14:08 fever ever recorded was a critical 115°F. Oh, and that person survived.
00:14:16 The pinky finger may be the smallest one, but it's the strongest one too.
00:14:21 It has 50% of all strength of your hand.
00:14:25 A human has about 20,000 to 25,000 genes.
00:14:28 Still, cornflakes have more genes than we do.
00:14:31 Luckily, it's about sophistication, not the quality this time.
00:14:36 Cornflakes 1, humans 0.
00:14:38 The iron our bodies have is enough to produce 3 nails, each 1 inch long.
00:14:44 The carbon that we have can be used for 900 pencils.
00:14:48 Your liver has a superpower of growing back removed parts.
00:14:52 It can regenerate to the original size from as little as a quarter of itself.
00:14:57 The coolest camera so far has 400 megapixels.
00:15:01 A human eye has 576.
00:15:04 That's why the sunsets are so much better in real life than in the photos.
00:15:09 A rollercoaster actually tosses your organs around.
00:15:13 When you feel as if your stomach's turning over, it might actually be the case.
00:15:17 Even though every person on Earth has an absolutely unique smell, identical twins smell exactly
00:15:24 the same.
00:15:25 It must be because they have identical genes.
00:15:28 Almost half of your taste buds will have gone away by the time you turn 60.
00:15:33 Your sense of smell gets less acute as you get older too.
00:15:37 When you cough, you release the air at about 60 mph.
00:15:41 Turnips can be a great remedy for cough.
00:15:44 Just slice them and add some honey on top.
00:15:46 A tablespoon three times a day is enough.
00:15:50 Our skin is the biggest organ that we have.
00:15:53 It's also one of the heaviest organs, weighing up to 9 pounds.
00:15:57 Hiccups is a two-step process.
00:15:59 First, you inhale a lot of air because of a muscle spasm, and then bang, the airways
00:16:04 are closed, the air is blocked, and the famous sound goes inside.
00:16:10 We don't smell when we sleep.
00:16:12 That's why it's almost impossible to notice a gas leak at night.
00:16:15 While sleeping, we can only rely on sound.
00:16:18 Well, actually, we can technically smell while we sleep, but normally a good shower can eliminate
00:16:24 that.
00:16:25 Out of all the senses we have, smell is the most acute one.
00:16:29 We remember 65% of smells after a year, but only 50% of things we've seen over the last
00:16:35 three weeks.
00:16:36 We also get a new nose every 28 days, because nose cells are renewed every 4 weeks.
00:16:43 As for taste, again, we mostly rely on our smell, since it helps us perceive up to 95%
00:16:49 of the flavor.
00:16:50 Without our smell sense, it'd be hard to tell an apple from a turnip.
00:16:55 While a bunch of flowers may be fragrant for you, there are people who suffer from cacosmia.
00:17:01 They always seem to smell something unpleasant, even if there's nothing like that around.
00:17:07 We need ears, not only for hearing, but for balance too.
00:17:11 Our vestibular system occupies the inner ear.
00:17:14 Canals in your inner ear contain fluid and tiny hair-like sensors helping you keep your
00:17:19 balance.
00:17:20 If you have red eyes in a photo, blame it on bouncing light.
00:17:25 The flash jumps off the blood vessels at the back of your eyes, creating that effect.
00:17:30 All the bones in your body are connected to each other except for the hyoid.
00:17:35 This bone serves as a support to your tongue, and it's one of the rarest bones to break.
00:17:41 Hey, check it out!
00:17:43 Your bones are designed to be used a lot every day.
00:17:46 Some of them can absorb the force of 2 or even 3 times your body weight.
00:17:50 That's impressive, but your teeth are even stronger.
00:17:54 When you bite something, they can withstand incredible pressure, up to 200 pounds.
00:17:59 By the way, the enamel is considered to be a part of your skeletal system.
00:18:04 Whenever you rotate your hand, the bones inside your forearm cross.
00:18:09 Grab hold of your arm and turn your palm to face first upward and then downward.
00:18:13 You'll make sure it's true.
00:18:16 Not only is your body 60% water, your bones contain some liquid too.
00:18:20 About 25% of the human bone mass is made up of water.
00:18:25 The human eye has something in common with a car engine.
00:18:28 They both can't work properly without various liquids.
00:18:31 The eye needs tears as much as the engine needs oil.
00:18:35 Tears should be evenly spread over the surface of your eye.
00:18:38 That's why you blink up to 20,000 times a day, and your eyelid plays the role of a windshield
00:18:44 wiper.
00:18:45 The only part of the human body that doesn't get any nutrients from blood is the cornea,
00:18:50 the clear front surface of the eye.
00:18:53 Instead, it's fed by tears on the outside and special fluids on the inside.
00:18:58 When you blush, it means there's increased blood flow in your body.
00:19:02 And then, not only your cheeks, but also your stomach lining gets somewhat red.
00:19:06 It's because it has plenty of blood vessels.
00:19:09 When there's more blood than usual in 'em, the lining blushes.
00:19:13 Your stomach lining gets replaced every 3-4 days.
00:19:16 This prevents the organ from eating itself.
00:19:19 The digestive acids there are exceptionally powerful.
00:19:22 People can accidentally swallow small objects, such as glass, plastic items, coins, and many
00:19:28 others.
00:19:29 Normally, they don't cause any harm and pass through the digestive tract within 48
00:19:34 hours.
00:19:35 Tiny quantities of plastic you might consume by mistake won't harm you.
00:19:39 But your stomach will have problems with digesting grass.
00:19:43 Grazing animals have special teeth and stomachs to process raw leaves and grass.
00:19:48 People aren't equipped that way.
00:19:51 The stomach is the most important protector of the immune system.
00:19:55 It contains hydrochloric acid.
00:19:57 This acid gets rid of dangerous food toxins, viruses, and bacteria that come along with
00:20:02 the food you eat.
00:20:03 The stomach itself would be digested by this strong acid if the mucous membrane didn't
00:20:09 protect it.
00:20:10 You've got two really fast muscles.
00:20:12 They control your eyelids closing.
00:20:14 They're the swiftest in your body.
00:20:16 Your eyes are fragile and need protection.
00:20:19 When a special reflex is triggered, for example, when something suddenly touches your eye,
00:20:24 these muscles only need 1/10th of a second to shut the eyelids.
00:20:29 Women usually blink more than men.
00:20:31 Plus, the older you get, the more frequently you do it.
00:20:35 By the way, when you watch a movie with a friend, you both blink in unison.
00:20:40 Do you think you owe your firm handshake to your strength workouts?
00:20:43 It's more likely thanks to your pinky.
00:20:46 Just kidding.
00:20:47 Well, the pinky is the strongest finger out there.
00:20:50 It's responsible for 50% of the entire hand's strength.
00:20:55 But the most used finger is the thumb.
00:20:57 If a person loses it, their hand becomes 40% less agile.
00:21:01 Oh, and the thumb has its own pulse, thanks to the artery running through it.
00:21:07 Your big toes carry more than 40% of your weight, more than all the other toes combined.
00:21:12 All in all, all your toes are a big deal.
00:21:15 They provide support and balance when you walk.
00:21:18 And when you run, they help you to be faster.
00:21:21 No more than 2% of people have natural red hair.
00:21:25 They're followed by blondes (about 3%) and all kinds of brown shades (about 11%).
00:21:31 But the world's most common hair colors are black and dark brown.
00:21:35 Hair is almost indestructible.
00:21:38 It can be burned or affected by strong acids, but that's pretty much all you can do to
00:21:43 destroy it.
00:21:44 Your hair usually stops growing at a certain length.
00:21:47 And since a hair lives for 2-7 years, its length doesn't normally exceed 42 inches.
00:21:53 Tell that to this lady from China, who got to the Guinness World Records with the longest
00:21:58 hair ever.
00:21:59 In 2004, it was a bit more than 18 feet 5 inches long.
00:22:04 Wow, what a drag!
00:22:07 Nails can grow staggeringly long too.
00:22:10 Some of the longest nails in the world belong to this guy from India.
00:22:13 Their combined length was 29 feet 10 inches, which is almost as long as a London double
00:22:19 decker.
00:22:20 The man cut them off back in 2018.
00:22:23 Nailed it!
00:22:25 Nails do help us catch small objects and peel stickers off.
00:22:28 But that's not all.
00:22:30 If you didn't have a rigid structure to press against, you wouldn't be able to understand
00:22:34 how firmly you should hold things.
00:22:37 Not only your hair and nails, but also your liver can grow.
00:22:41 It's the largest internal organ by mass.
00:22:44 The liver can fully regenerate from only 51% of its original mass back to the full size.
00:22:50 At the same time, constant damage to the liver will result in scars.
00:22:55 The largest organ in your whole body is the skin.
00:22:59 It makes up more than 15% of your total body weight.
00:23:03 People lose 30,000 to 40,000 skin cells every single minute.
00:23:08 That adds up to 9 pounds of skin cells a year.
00:23:11 You know that dust in your house?
00:23:13 Now you know where some of it comes from.
00:23:17 The tongue isn't the only organ that helps you recognize taste.
00:23:20 Your nose also plays a critical role in this process.
00:23:24 It's often said the nose is responsible for 75 to 95% of your taste perception.
00:23:30 Try holding your nose next time you eat.
00:23:33 Gnaw on an onion or eat some smoked fish.
00:23:36 It's not that you won't feel any taste at all, but it's gonna be way blander.
00:23:41 Your taste buds won't work properly if your mouth is too dry.
00:23:45 You simply won't feel the taste until the food is covered in saliva.
00:23:49 It contains enzymes, which are complex protein molecules.
00:23:53 They start to break down your food as soon as it gets into your mouth.
00:23:57 A recent study has found out that people can distinguish more than a trillion smells.
00:24:02 You tend to remember odors better than sounds or images.
00:24:06 That's why smells can evoke distant memories.
00:24:09 When you're asleep, you don't feel any odors.
00:24:12 Your sense of smell basically deactivates at night.
00:24:15 Even if there's some terrible stench in your bedroom, you won't notice it.
00:24:19 I'm sure my dog is relieved to hear that.
00:24:22 The color of your dreams seem to be affected by the TV you watched as a kid.
00:24:27 If it was black and white, you'd probably see monochrome dreams more often than not.
00:24:33 If you're used to color television, your dreams are likely to be colorful.
00:24:38 What kind of dreams did people in the Middle Ages have then?
00:24:41 Knights that say "knee"?
00:24:43 Your heart can give you away when you lie by starting to beat faster.
00:24:48 Women's hearts are usually smaller than men's.
00:24:50 That's why they have to work harder and make more beats.
00:24:53 Otherwise, they won't be able to pump enough blood.
00:24:56 Even if you brush your teeth twice a day and never forget about mouthwash, your mouth still
00:25:01 remains one of the dirtiest parts of your body.
00:25:05 Millions of bacteria live there.
00:25:07 The good news is that most of them are good for your health.
00:25:10 They protect your body from bad bacteria and viruses.
00:25:14 The second dirtiest place is your belly button.
00:25:17 You don't really use it after you were born.
00:25:19 So this forlorn area accumulates all kinds of germs, sweat, and dirt.
00:25:25 The belly button has over 2,300 bacterial species, and it does need extra attention.
00:25:32 They say eyes don't grow with the rest of the body.
00:25:35 Well, it's not 100% true because the eyes aren't fully developed until you're about
00:25:40 21.
00:25:41 But the absolute growth champions here are your ears and nose.
00:25:46 They never stop growing.
00:25:47 Wow, what was that thing about elephants again?
00:25:50 Must've been a different video.
00:25:53 If all your blood vessels were stretched into a single line, dang, you would be in a really
00:25:58 tough spot.
00:25:59 But they would go round the Earth four times.
00:26:02 You can't tickle yourself, no matter how hard you try.
00:26:06 You've just checked that and failed, haven't you?
00:26:09 That's because your brain warns you that you're about to be tickled, which it can't
00:26:13 do if it's someone else.
00:26:15 Ever wondered why you feel so sleepy after lunch?
00:26:18 One of the reasons is your circadian rhythm, which runs on a 24-hour cycle.
00:26:23 It demands that you have a nap 7 hours after waking up.
00:26:27 And the food just adds to this effect.
00:26:29 As simple as that.
00:26:30 Oops, excuse me, it's time!
00:26:33 (snoring)
00:26:34 (ding)
00:26:35 Oh, the phone's ringing.
00:26:37 Must be something urgent.
00:26:38 At 11 p.m.?
00:26:40 Only all the gadgets in the house are silent.
00:26:43 It's your ears that are ringing.
00:26:45 We can also hear some hissing, whistling, buzzing, and even roaring.
00:26:49 But all this noise doesn't have an external source.
00:26:53 Ooh, that's why it's known as "phantom sounds."
00:26:56 They can occur in one or both ears, constantly or from time to time.
00:27:01 They're usually most noticeable at night when nothing distracts you.
00:27:05 Hearing noise in your ears is called tinnitus.
00:27:08 It's quite common and affects 15-20% of people.
00:27:12 Tinnitus starts in the part of your inner ear shaped like a snail.
00:27:15 It's called the cochlea.
00:27:19 Your middle ear picks up sound waves.
00:27:21 They get translated into electrical impulses in the inner ear.
00:27:25 Then, sensory nerves carry these impulses to your brain.
00:27:29 If your inner ear works incorrectly, your brain can misinterpret the sounds.
00:27:35 Tinnitus occurs when there are some changes in the cochlea's nerve.
00:27:39 They can be caused by loud noise, like chainsaws, jackhammers, loud music, or shouting!
00:27:45 Tinnitus can start after a head, neck, or ear injury, or after you begin to take certain
00:27:50 medications.
00:27:51 You can also hear ringing in your ears if you have some blood pressure issues.
00:27:55 Elsewhere, in the amazing human body, some of the bacteria living in your gut can produce
00:28:01 electricity!
00:28:02 Shocking!
00:28:03 They give off electrons, and this creates tiny electrical currents.
00:28:07 That's likely to be the bacteria's backup system – their way to generate energy.
00:28:13 Humans are the only animals that have chins.
00:28:16 Even our closest genetic relatives, gorillas and chimps, lack this small piece of bone
00:28:21 that extends forward from the jaw.
00:28:23 Their lower jaws slant down and back from their front teeth.
00:28:28 Scientists still haven't figured out this mystery.
00:28:30 The opinions about why people are made this way differ.
00:28:33 Some researchers think chins help us chew our food.
00:28:37 Others are sure they have something to do with speaking.
00:28:39 A few of us think it's simply a special place to grow a goatee.
00:28:44 Blinking keeps your eyes clean and moist.
00:28:47 But that's not all!
00:28:48 Every time you blink, you take a micro-nap.
00:28:51 Researchers from Washington University have found out that blinking makes your attention
00:28:56 sharper and works as a teeny recharge.
00:29:01 Ever seen tiny dots traveling in squiggly lines, especially when you're looking at
00:29:05 a bright blue sky?
00:29:07 These dots are only visible for a second or so and might look like itty-bitty worms.
00:29:13 Those are your white blood cells moving through the capillaries in front of the retina.
00:29:17 That's the light-sensitive tissue at the back of your eyes.
00:29:21 Curiously, most people don't even notice the dots unless asked to pay attention.
00:29:26 The pineal gland in your brain handles the production of melatonin.
00:29:30 That's the very hormone that regulates your sleep patterns.
00:29:34 The gland looks like a pine nut, and that's how it got its name.
00:29:39 The human brain is 73% water, and the same is true about the heart.
00:29:43 That's why if your brain loses even 2% of liquid, you start to feel tired.
00:29:49 It also makes your memory worse, shortens your attention span, and puts a dampener on
00:29:54 your mood.
00:29:56 By the way, your brain makes sure you don't drink too little or too much water.
00:30:01 If you swallow some liquid, your mouth and throat start to fire signals to your brain,
00:30:06 telling it to stop drinking.
00:30:07 Otherwise, you'd be gulping down water for the entire 10-60 minutes it takes the liquid
00:30:13 to get to your cells.
00:30:15 Your eyes can see something for a mere 13 milliseconds, and your brain will already
00:30:20 process this image.
00:30:21 For comparison, the average blink lasts from 100 to 400 milliseconds.
00:30:27 Even though the tongue isn't the strongest muscle in your body, it never gets tired.
00:30:32 That's because of the way it's built.
00:30:34 It's made up of 8 interwoven muscles.
00:30:37 But unlike other muscles in your body, these aren't situated around a supporting bone.
00:30:42 The tongue's structure is similar to an elephant's trunk or an octopus's tentacles.
00:30:50 Your body emits visible light.
00:30:52 That's why they call me sunny.
00:30:55 You're the brightest at 4 PM, and your glow is the least visible at 10 AM.
00:31:01 Unfortunately, this glowing is a thousand times less intense than what your eyes can
00:31:05 see.
00:31:07 Sweat is mostly water mixed with proteins, sugars, ammonia, and a lot of other stuff.
00:31:13 It even contains tiny amounts of trace metals, like copper, zinc, nickel, iron, and so on.
00:31:19 What makes sweat taste salty is the sodium it contains.
00:31:23 Plus, the more salt you eat, the saltier your sweat is.
00:31:27 Your body's trying to get rid of the excess, and the fastest way is to sweat it out.
00:31:32 In an adult, the blood makes up 7-8% of the total body weight.
00:31:37 About 55% of your blood is liquid plasma.
00:31:41 The rest is red and white blood cells and platelets.
00:31:44 They form clots and prevent bleeding.
00:31:47 You can't swallow and breathe at the same time.
00:31:50 The food you swallow and the air you breathe go down the same part of your throat at first.
00:31:56 Only a bit deeper, the passage splits into the esophagus (for food and liquid) and trachea
00:32:01 (for air).
00:32:03 When you swallow, your airway gets automatically closed off.
00:32:06 This prevents you from accidentally inhaling food.
00:32:10 But occasionally, it still happens.
00:32:13 Your brain sometimes generates more than 48 thoughts in just one minute.
00:32:18 That's almost 3,000 thoughts per hour and 69,000 per day!
00:32:23 - Fingernails grow faster on the dominant hand.
00:32:26 If you use your right hand more, you'll have to trim nails on it more often.
00:32:31 Fingernails also grow more quickly in the summer and during the day.
00:32:35 - You might keep in memory up to 10,000 different faces.
00:32:38 Sure, it varies from person to person, and the average number is 5,000.
00:32:43 That doesn't mean you can put a name to each of these faces; it's only about recognizing
00:32:48 the features.
00:32:50 - You might try to hide the truth, but your nose will always give you away.
00:32:55 When a person tells a lie, the temperature around their nose and in the inner corners
00:32:59 of their eyes goes up.
00:33:01 This phenomenon is known as the Pinocchio effect.
00:33:07 - Women have more taste buds on the surface of their tongues than men do.
00:33:11 That's one of the reasons why 35% of ladies and only 15% of guys are supertasters.
00:33:18 Those are people who feel flavors more strongly than others.
00:33:21 - Your teeth are the only part of your body that can't repair itself.
00:33:26 But the enamel they're covered with is one of the toughest things in the human body.
00:33:31 - Your heartbeat often syncs with the music you're listening to.
00:33:34 If a piece has a continuous increase in volume or tempo, like rock, it can make your heart
00:33:39 rate faster.
00:33:41 Some classic music lowers heart rate and blood pressure.
00:33:44 This phenomenon affects everyone from professional musicians to amateurs and music lovers.
00:33:51 - There are 2 to 5 million sweat glands on your body.
00:33:54 The sweat they produce is of two different kinds – stress sweat and regular sweat.
00:34:00 Hey, don't sweat the small stuff, huh?
00:34:02 The sweat caused by stress has fatty acids and proteins in it.
00:34:07 And the regular sweat is mostly made up of water, salt, and a tiny bit of other substances.
00:34:13 - It's actually possible to brush your teeth too thoroughly and hard.
00:34:17 This can wear down the enamel and make your teeth super sensitive to cold and hot foods.
00:34:23 - If you walked in the same direction for 12 hours a day, you would need around 800
00:34:28 days to travel around the globe.
00:34:30 And don't forget your rubber boots for the ocean parts.
00:34:34 - If your stomach acid made contact with your skin, it would most likely eat a hole in it.
00:34:40 All because of hydrochloric acid.
00:34:42 This type of acid is incredibly potent.
00:34:45 It can easily dissolve some metals, for example, magnesium or zinc.
00:34:51 Hydrochloric acid is the main component of the gastric acid your stomach produces.
00:34:55 It protects your immune system and gets rid of viruses and bacteria in the food you eat.
00:35:00 This acid also helps your body break down, digest, and absorb all kinds of nutrients,
00:35:06 including proteins.
00:35:08 - Your lips look red because there is a great concentration of miniature blood capillaries
00:35:13 right below the skin.
00:35:16 - Your pinky is a powerful little thing.
00:35:19 Without it, your hand would lose a significant part of its power.
00:35:22 Your index and middle fingers cooperate with your thumb to grab and pinch.
00:35:27 And your pinky, together with your ring finger, provides grip strength.
00:35:32 - The fattest organ in your body is your brain.
00:35:36 Fat makes up at least 60% of its dry weight.
00:35:40 This quality got the brain to the Guinness World Records.
00:35:43 The organ contains around 25% of your body's cholesterol, which is vital for the brain's
00:35:48 well-being.
00:35:49 So, is that where the term "fat head" comes from?
00:35:54 - Your skeletal cells never stop regenerating.
00:35:57 That's why you get a new skeleton every 10 years or so.
00:36:01 This process slows down with age, and the regeneration takes longer.
00:36:05 That's one of the main reasons why bones become thinner.
00:36:09 - And there's a newly discovered type of brain cells crucial for visual search.
00:36:14 They're called target cells.
00:36:16 Without their help, you wouldn't be able to spot an acquaintance in a crowd or your
00:36:20 dog in the park.
00:36:22 Interestingly, target cells don't care what the thing you're searching for looks like.
00:36:26 All they want to know is whether an object is your target or not.
00:36:30 Hey, it's not picky!
00:36:34 - Your brain will grow by roughly 2% if you venture into space.
00:36:40 Under normal gravity, it is thought that fluid in the brain naturally moves downwards when
00:36:45 we stand upright.
00:36:47 But there is evidence that lack of gravity prevents this, which is why fluid accumulates
00:36:52 in the brain and skull.
00:36:54 - While a bunch of flowers may be fragrant for you, there are people with cacosmia who
00:36:59 would beg to differ.
00:37:00 They perceive all the smells out there as something odorous.
00:37:03 Well, that stinks!
00:37:06 - Speaking of which, out of all the senses we have, smell is the most acute one.
00:37:11 We remember 65% of smells after a year, but only 50% of what we've seen over the last
00:37:18 three weeks.
00:37:19 We also get a new nose every 28 days, because the nose cells are renewed every 4 weeks.
00:37:26 - We don't smell when we sleep.
00:37:28 Well, of course, unless you haven't bathed in a while.
00:37:31 Your sense of smell goes to sleep when you do, which is why it's almost impossible to
00:37:36 notice a gas leak at night.
00:37:38 While sleeping, we rely only on sound because the sleep can be disrupted by noise.
00:37:44 - Almost half of your taste buds will have gone away by the time you turn 60.
00:37:48 So maybe you will finally start eating those broccoli!
00:37:52 Your sense of smell gets less acute as you get older as well.
00:37:56 - As for taste again, we mostly rely on our smell since it helps us perceive up to 95%
00:38:03 of the flavor.
00:38:04 Without the sense of smell, it'd be hard to tell an apple from a turnip.
00:38:09 - When you cough, you release the air at about 60 mph, so mind the speed limit.
00:38:15 - Hiccups is a two-step process.
00:38:17 First, you draw in a lot of air because of a muscle spasm, and then bang, the airways
00:38:23 are closed, the air is blocked, and the famous sound goes outside.
00:38:29 - We need ears not only for hearing but for balance too.
00:38:33 Our vestibular system occupies the inner ear.
00:38:36 Canals in your inner ear contain fluid and tiny sensors helping you keep the balance.
00:38:42 - By the way, ears have bones.
00:38:45 These are also the only bones that never grow.
00:38:47 We can hear thanks to these little guys since they transmit sound vibrations.
00:38:53 Doctors call them "oscular chain," and it's made up of malleus, incus, and stapes,
00:38:58 nicknamed hammer, anvil, and stirrup, which are integral parts of the middle ear.
00:39:04 - Our ears keep growing throughout our lives.
00:39:06 They sweat too, and earwax is actually a kind of sweat they produce.
00:39:11 By the way, the nose never stops growing either, perhaps from all the lies.
00:39:18 - Your heart is the only muscle that never gets tired.
00:39:21 The aorta is massive; its diameter is almost as large as a hose in your garden.
00:39:28 - All the bones in our body are connected to each other except for the hyoid, which
00:39:33 doesn't articulate with the other bones.
00:39:35 This bone serves as support to your tongue, and it's one of the rarest bones to break.
00:39:41 - If you have red eyes in a photo, blame it on bouncing light.
00:39:45 The flash jumps off the capillaries in your retina, creating that effect.
00:39:50 - As for eyes, the coolest camera so far has 200 megapixels.
00:39:54 The human eye has 576.
00:39:57 That's why sunsets are so much better in real life than in photos.
00:40:01 - A roller coaster actually tosses your organs around.
00:40:05 When you feel like your stomach's falling down, it's really flipping inside your body.
00:40:10 - Lips are much more sensitive than fingers, having around a million nerve endings.
00:40:15 They are 100 times as sensitive as the tips of the fingers.
00:40:19 - Grooves and furrows make our lip print unique, just like fingerprints are.
00:40:24 They also remain unchanged throughout our life.
00:40:27 The tongue print is unique too, by the way.
00:40:30 - Even though all the people on Earth have an absolutely unique smell, identical twins
00:40:35 smell exactly the same.
00:40:37 It must be because they have identical genes.
00:40:40 - Usually, we shed about 50 to 150 hairs a day.
00:40:45 An average lifespan for hair is 5 years, and as soon as an old hair says goodbye to your
00:40:51 scalp, a new one starts growing immediately.
00:40:54 - In your body, you carry enough bacteria to fill a can.
00:40:59 Bacteria makes about 3 to 5 pounds of your weight, representing 2% of your total weight.
00:41:04 Still, most of them are the waste that our body has.
00:41:08 - A human being has about 20,000 to 25,000 genes.
00:41:13 Seems impressive, right?
00:41:14 Well, cornflakes have more genes than we do.
00:41:17 Luckily, it's about sophistication, not the quantity.
00:41:21 Anyway, cornflakes 1, humans 0.
00:41:25 - We consist of many chemical elements, including iron.
00:41:28 The iron in our bodies is enough to produce 3 nails, each 1 inch long.
00:41:34 - The carbon that we have can be used for 900 pencils.
00:41:38 Our feathers can be used to make quill pens.
00:41:40 Wait, that's birds.
00:41:42 Never mind.
00:41:43 - Our liver has a superpower of regenerating if part of it was removed.
00:41:48 It can grow back to the size that your body needs.
00:41:51 - Fat helps our bodies consume vitamins.
00:41:54 Such vitamins as A, D, K, and E can be properly absorbed only when fat dissolves.
00:42:01 Our bodies have enough fat to produce 7 bars of soap.
00:42:05 Don't try this at home.
00:42:07 - When we're awake, our brain may produce enough energy to turn an electric bulb on.
00:42:12 It has 10 watts of power.
00:42:15 What's that about?
00:42:17 - Our belly buttons have an entire animal encyclopedia in them, with a range of about
00:42:22 70 different bacteria.
00:42:24 Some of them can be also found in the soil of Japan, and even in polar ice caps.
00:42:30 - Our bodies actually glow.
00:42:32 Anyway, we can't see that with an unaided eye because the light we emit is 1,000 times
00:42:38 less intense than the minimum level we can perceive.
00:42:42 - Speaking of which, carmine used blushes and lipsticks is red dye made up of ground-up
00:42:48 beetles.
00:42:49 Oh.
00:42:50 - Saliva helps to taste food.
00:42:53 Our taste buds are ready to perceive it only when it's dissolved by saliva.
00:42:58 - An eyelash is here to stay for 150 days only.
00:43:02 The world eyelash record was about 3 inches long.
00:43:06 They're also home for tiny mites.
00:43:09 - We blink about 4,200,000 times a year, at least once every 8 seconds.
00:43:15 It'd be cool if we were given a scent every time we blinked.
00:43:19 We could make more than $100 daily.
00:43:22 - It may sound crazy, but our bones are stronger than lots of building materials.
00:43:26 A cubic inch of human bone can bear about 19,000 pounds, making it 4 times stronger
00:43:33 than concrete.
00:43:35 - The only thing that makes our blood type different is sugar.
00:43:39 AB and AB types have sugars, while O has none, which makes it perfect for donors.
00:43:46 No sugar doesn't make O type less sweet.
00:43:48 In fact, it attracts mosquitoes even more than the other blood types.
00:43:53 - People have only 8 blood types, while cows have 800 and possibly more.
00:43:59 Like what, Moo Positive and Moo Negative?
00:44:02 - Our fingernails grow way faster than toenails.
00:44:05 They grow almost 4 times slower because they have less damage than fingernails.
00:44:10 Even though we stumble on them often, sudden circulation bursts usually don't last long.
00:44:17 - Nails don't only help us catch random tiny objects and peel the stickers off.
00:44:22 If you didn't have a rigid structure against which to press, you wouldn't be able to
00:44:26 judge how firmly to hold anything.
00:44:29 - Very few people can actually digest milk.
00:44:32 The thing is, there's some special enzyme, let's call it a little helper, that breaks
00:44:37 down the sugars any milk has.
00:44:40 When people grow up, they run out of this enzyme.
00:44:43 This sugar's called lactose, so adults that can't digest it are lactose intolerant.
00:44:50 68% of the world's population can't actually digest milk.
00:44:55 - If you're sleeping, it doesn't mean your whole body rests.
00:44:58 In fact, sometimes your brain has to work even harder when you're asleep.
00:45:03 It needs to process tons of information, and reports usually take a lot of time.
00:45:09 - Humans can't multitask.
00:45:10 Really.
00:45:11 We need time to switch from one task to another, but if we try to tackle several things at
00:45:16 the same time, it's not going to be very productive.
00:45:20 - Try this one.
00:45:21 Lift your right foot and start rotating it in a clockwise direction.
00:45:25 Try to write the number 6 with your big toe in the air.
00:45:28 Now, check the direction your foot's moving.
00:45:31 It's moving in the opposite direction, because to write the number 6, you need to make a
00:45:36 counter-clockwise movement.
00:45:38 It actually takes a bit longer to start a new habit.
00:45:41 It's not 100% true that 18 or 21 days are enough, as many people think.
00:45:48 The process of getting a new habit can take up to 254 days, but on average, it takes around
00:45:54 66 days for a new habit to become automatic.
00:45:58 - Here's some fats you'll find hard to digest.
00:46:03 Your stomach has a pretty incredible capacity, being able to hold up to half a gallon of
00:46:08 liquids.
00:46:09 That's a whole large bottle of Coke!
00:46:12 - It's pretty hard to estimate how much hard food you can eat because it's processed with
00:46:17 your teeth before it gets to your stomach.
00:46:20 There's definitely not enough room for a turkey, but a good-sized chicken would probably fit
00:46:24 in it.
00:46:26 - If you were asked where your stomach was, you would probably point to your tummy.
00:46:31 Sorry, that's wrong.
00:46:33 It's actually up here, hidden in between your ribs.
00:46:38 - Scientists believe that the appendix will disappear eventually.
00:46:41 Nobody really knows why we need it, but some researchers claim it might've existed to help
00:46:46 our ancestors digest tree bark.
00:46:49 Because it's no longer part of our daily diet, the appendix isn't necessary and can
00:46:54 disappear from our bodies without any consequences.
00:46:58 - The appendix isn't the only obsolete part of our body.
00:47:02 Wisdom teeth aren't that useful either.
00:47:04 Yeah, they used to come in handy whenever our ancestors lost some of their teeth, but
00:47:09 the only thing they help us lose now is the money we spend extracting them.
00:47:15 - Almost all of our body is covered with hairs, even if we don't notice them.
00:47:19 They grow even in the belly button.
00:47:22 Their purpose is to catch lint.
00:47:23 Check it out.
00:47:25 See?
00:47:27 - Your liver acts as your own personal bodyguard, protecting you from toxins and many other
00:47:32 things you don't want hanging around in your body.
00:47:35 It's also pretty indestructible and can even regenerate.
00:47:40 - Only about 43% of you is actually you.
00:47:44 Over 50% of the cells in your body belong to tiny little creatures that mainly live
00:47:49 in your gut.
00:47:50 Still, even though your own cells are fewer than microbial ones, there are, on average,
00:47:56 about 100 trillion of them in you.
00:47:59 See?
00:48:00 You're not alone.
00:48:02 - With this in mind, your own genes are less than half of what you really consist of.
00:48:07 If you take all the microbes dwelling within your body and count their genes, you'll find
00:48:11 between 2 to 20 million.
00:48:16 - If you sleep, it doesn't mean all of your body sleeps.
00:48:19 In fact, sometimes your brain has to work even harder when you're asleep.
00:48:23 It needs to process tons of information, and reports usually take a lot of time.
00:48:30 - The nose definitely gets a good rest while you're sleeping.
00:48:33 Amazingly, your sense of smell basically deactivates at night.
00:48:38 You wouldn't even be bothered if there was a really terrible smell in your bedroom.
00:48:42 No comment.
00:48:44 - The nose is probably one of the most underappreciated parts of the body.
00:48:49 We wouldn't even be able to enjoy eating without it.
00:48:52 About 80% of the taste of any food is thanks to the nose and its ability to recognize odors.
00:48:58 If you hold your nose while eating, you will taste almost nothing.
00:49:03 With no sense of smell, you're likely to recognize food mostly by texture.
00:49:07 So an onion might seem no different than a big refreshing apple.
00:49:11 Yeah, try that and leave me a comment on how that goes.
00:49:17 - Scientists used to believe we could distinguish about 10,000 smells, but they were wrong.
00:49:22 Recent research showed that people are actually able to distinguish between more than a trillion
00:49:27 smells.
00:49:28 We also remember them better than anything else, and smells can even evoke some distant
00:49:33 memories.
00:49:35 - Your nose just doesn't help you breathe and catch odors.
00:49:38 It filters the air for sensitive throats and lungs.
00:49:42 If we inhale dry air, the nose moistens it, cools it, and heats it if it's necessary.
00:49:48 Also the nose cleans the air of dirt.
00:49:52 - When you age, your brain is gradually reducing in size.
00:49:56 By age 75, it's much smaller than at 30, and it starts shrinking by the age of 40.
00:50:02 It happens to everyone, and doesn't affect your mental strength in any way.
00:50:08 - Our brain can store only 7 bits in its short-term memory.
00:50:12 Don't even try to compare your brain with a phone capacity, not even the one you had
00:50:16 back in 2005.
00:50:18 That's why you can't even learn a phone number by heart.
00:50:22 - Our short-term memory functions just like a chalkboard.
00:50:25 You can get some information, but sooner or later, you run out of space.
00:50:30 To check your working memory capacity, try this test.
00:50:34 Ask a friend to write a list of 10 words and read it to you.
00:50:37 Most people recall 7 or fewer items from that list.
00:50:42 - Your RAM, or working memory, is an essential thing that we need to perform almost any everyday
00:50:48 activity, including basic conversations, surfing the net, and even petting your dog.
00:50:55 - Our strongest and emotional memories are often fake.
00:50:59 The central memory gives us the confidence to believe that we remember everything, even
00:51:03 though most of the details are made up in our heads.
00:51:08 - Not only your brain shrinks as you get older, you too shrink dramatically.
00:51:12 The bones get more brittle, the backbone gets compressed.
00:51:16 A similar thing happens when you rest at night.
00:51:19 Your bones kinda relax too.
00:51:21 Because of this, you wake up taller in the mornings than you are at the end of the day.
00:51:27 - Even mammals, only humans can walk on two legs for their entire lives.
00:51:32 You might think that kangaroos or gorillas move in the same way, but kangaroos use their
00:51:37 tail as a third leg, and gorillas use their long arms to keep balance.
00:51:44 - Your bones take part in metabolism too.
00:51:46 Since they mostly consist of calcium, when there's not enough of this element in your
00:51:50 blood, bones start shedding it into the bloodstream, balancing your body.
00:51:55 The same reaction works in reverse too.
00:51:58 When there's too much calcium in your blood, it goes into the bones to be stored for later.
00:52:04 - The only bone to have a sense of humor in your body is inside your upper arm.
00:52:09 That's why it's called the humerus.
00:52:11 Okay, I made that one up.
00:52:13 Moving along…
00:52:15 - The only bones that never grow are found in our ears.
00:52:19 We can hear, thanks to these tiny bones, because they have adapted to transmit sound vibrations.
00:52:25 Doctors call them the oscular chain.
00:52:27 One of these hearing bones, the stapes, is the smallest bone in your entire body.
00:52:32 It's no larger than a grain of rice.
00:52:36 - Our height, shape of our body, and skin color depend a lot on where our ancestors
00:52:41 used to live.
00:52:43 But we can adapt to new conditions even within our own lifespan.
00:52:47 For example, if you move from plains to the mountains, you'll eventually develop more
00:52:52 red blood cells to compensate for the lack of oxygen.
00:52:56 And naturally, if you move from a colder climate to a hotter and sunnier one, your skin will
00:53:01 get darker to adapt.
00:53:04 - Our lifespan is programmed within our cells.
00:53:07 They constantly renew and divide, but they have a sort of internal timer that stops at
00:53:12 some point.
00:53:13 Some cells also stop reproducing sooner than others.
00:53:17 On average, cells cease dividing when we reach the age of 100.
00:53:21 That means if we could find a way to trick ourselves into turning off the timer, we could
00:53:26 potentially live forever.
00:53:30 - Body fat isn't just a nuisance.
00:53:32 It acts as insulation material, energy reserve, and shock absorber.
00:53:36 Your body sends the most fat into your waist region because that's where your internal
00:53:41 organs are.
00:53:42 If something happens to you, this layer of fat might protect your vitals from irreparable
00:53:47 damage.
00:53:50 - Heads up, your skull isn't a single bone.
00:53:53 It actually consists of 28 different bones, many of which are fused together to protect
00:53:58 your brain.
00:53:59 The mandible, or the lower jaw, is the only skull bone that isn't fixed to the bone around
00:54:04 it.
00:54:05 It's attached with connective tissues and muscles.
00:54:08 This is what makes it so mobile – you can move it in any direction you like.
00:54:12 You can actually masticate with your mandible!
00:54:15 Another word for chewing.
00:54:18 You see, the strongest muscles in your body aren't in your arms or legs – they're
00:54:22 in your head.
00:54:23 The masseter is the main muscle responsible for chewing, and it needs to be the strongest
00:54:28 for you to eat normally.
00:54:30 And you know those muscles that allow you to move your ears?
00:54:33 Those are temporalis, located above your temples.
00:54:36 They also help you chew your food.
00:54:40 - We've got two really fast muscles – they control the eyelid closing.
00:54:44 In fact, they're the fastest muscles in our body.
00:54:48 Eyes are fragile and need protection, so the reflex that protects them needs to be as fast
00:54:53 as lightning.
00:54:54 These muscles can shut the eyelids in less than a tenth of a second.
00:55:00 - People with double-jointed thumbs can bend them backward.
00:55:02 It looks super unusual, and very few people can do it.
00:55:06 Still, it's totally okay.
00:55:08 Even though it looks painful, it actually doesn't hurt at all for someone with a double-jointed
00:55:13 thumb.
00:55:15 - We recognize only purple-blue, green-yellow, and yellow-red colors.
00:55:20 Everything else is a combination of these three.
00:55:23 It's impossible to calculate how many of these combinations the human eye sees, because
00:55:28 every single person has slight vision differences.
00:55:32 But it's about 1 million combinations on average.
00:55:35 You see?
00:55:39 - Whenever we yawn, we use the muscles in our mouth and tongue, and the contact can
00:55:44 squeeze some of the saliva-producing glands.
00:55:47 As a result, we might squirt a tiny stream of saliva without even noticing it, but it'll
00:55:53 reach out a foot or more.
00:55:55 I had a friend in college who could do that at will.
00:55:58 It was impressive.
00:56:00 - It turns out that saliva is basically filtered blood.
00:56:03 Blood is processed thanks to special glands, and special cells absorb its properties.
00:56:09 After that, the blood becomes saliva.
00:56:13 - Moving on, if your brain were a USB drive, it would be totally insane.
00:56:18 Our brain capacity is somewhere between 10 and 100 terabytes.
00:56:23 Some scientists claim the full spectrum can reach 2.5 petabytes.
00:56:28 Sounds like a dog snack, doesn't it?
00:56:30 Given the size of the full English version of Wikipedia was calculated back in 2010,
00:56:36 it was only 5.6 terabytes.
00:56:39 - Our body heat can boil a half a gallon of water in 30 minutes, even when we're idle.
00:56:45 We should try that.
00:56:47 - Our brain can perform up to 10 quadrillion operations per second with 10 watts of power
00:56:53 only.
00:56:54 A computer that could do the same would need about 1 gigawatt of power.
00:56:58 This amount could power up to 300,000 houses.
00:57:03 - Your memory is affected by your body position.
00:57:06 For example, you're much more likely to recall a situation where you waved to someone if
00:57:11 you stand and wave again.
00:57:14 - Your brain has millions of neurons.
00:57:16 They're all different, and the speed of connection between them is different too.
00:57:21 That's why you can recall some information faster than others.
00:57:26 - Our nerve impulses, though, are super slow compared to the speed of electricity.
00:57:31 Neurons can speed up to 275 mph, even slower than the world's fastest car.
00:57:37 Still, it's pretty fast because your brain needs to respond to stuff like pain or tickles.
00:57:44 - The brain itself, by the way, can't feel pain.
00:57:47 It has no nerve endings of its own.
00:57:50 - People with red-colored hair are 1% of all people.
00:57:54 2% are natural blondes.
00:57:57 So yeah, most people you see with these hair colors have dyed hair.
00:58:02 Black is the most common hair color in the world.
00:58:06 - Hair is not only strong but also elastic.
00:58:10 It can stretch about 30% of its length when it's wet.
00:58:14 - The average hair growth rate is 6 inches per year.
00:58:18 So if you never cut your hair until you're, say, 80 years old, your hair will have grown
00:58:23 up to 480 inches, about the height of a 4-story building.
00:58:27 Still, it's not quite possible because our hair length is programmed genetically.
00:58:34 - A human eye resembles a car engine.
00:58:36 Both of them need liquid for good lubrication.
00:58:40 The engine needs oil, and the eye needs tears.
00:58:43 To make sure the eyes work right, tears are distributed all over them.
00:58:48 That's why we blink more than 10,000 times a day.
00:58:52 The eye muscle is the fastest muscle in our bodies.
00:58:55 We can blink 5 times per second and even more.
00:58:59 We spend about 6 seconds blinking every minute.
00:59:03 During the day, we spend 30 minutes in complete darkness just because we close the eyes, not
00:59:08 even including the time when we sleep.
00:59:12 - The only part of the human body that doesn't get any nutrients from blood is the cornea
00:59:17 of the eye.
00:59:18 The only thing it needs to work well are tears and fluid in front of your eyes.
00:59:24 - Most scientists agree that tears that appear out of emotion are a unique human feature.
00:59:29 No other animal is capable of crying because of sadness or joy.
00:59:35 - The pupils narrow and expand in order to control the incoming light.
00:59:39 If there's a lot of light, they narrow the passage for light so as to not harm the vision.
00:59:45 In the dark, the pupils expand to capture as much light as possible.
00:59:50 - Now back to our mouths.
00:59:52 The tongue has a lot of muscles, and some of them can strain only when you're learning
00:59:57 a new language.
00:59:59 - A human bite almost always becomes infected because of all the bacteria that live in our
01:00:04 mouth.
01:00:05 In this sense, we're quite close to hyenas.
01:00:09 - Your bones are designed to be used a lot daily, and some of them can absorb 2 or even
01:00:14 3 times your body weight.
01:00:16 That's impressive, but your teeth are even stronger.
01:00:20 When you bite something, the teeth can exert incredible pressure, up to 200 pounds.
01:00:26 By the way, the enamel is considered to be a part of your skeletal system.
01:00:32 - Our body is about 60% water, and it can be found even in bones.
01:00:37 About 25% of the human bone mass is made of water.
01:00:43 - Hydrochloric acid in our stomach, also known as the most important defender of the immune
01:00:48 system, helps get rid of dangerous food toxins, viruses, and bacteria you get with the food
01:00:54 you eat.
01:00:55 Even the stomach itself can be digested by this acid, but the mucous membrane protects
01:01:00 it.
01:01:02 - Even if you brush your teeth twice a day and never forget about mouthwash, your mouth
01:01:06 still stays one of the dirtiest parts of the human body.
01:01:12 - Thousands of bacteria live inside it.
01:01:14 The good news is that most of these bacteria are good for the body and protect it from
01:01:19 bad bacteria and viruses.
01:01:23 - People and giraffes have similar necks.
01:01:26 A person has the same amount of neck vertebrae as a giraffe has.
01:01:30 The difference, though, is about the length.
01:01:32 Giraffe vertebrae are about 10 inches long.
01:01:36 - Our spine can withstand pressure of up to 1,000 pounds.
01:01:40 It would withstand an adult zebra.
01:01:44 But please don't try it at home – there are no zebras there after all.
01:01:49 When you lie down on your back and elevate the knees, the pressure on your spine is about
01:01:54 25 pounds.
01:01:55 Not a zebra for sure, but a good-sized cat.
01:01:59 - Our spine is also very flexible.
01:02:02 If we could bend it, it could possibly form two-thirds of a complete circle.
01:02:06 Are we like snakes, then?
01:02:09 - In the morning, you're taller than in the evening.
01:02:12 While sleeping, you're no longer affected by the force of gravity.
01:02:16 And your spine stretches, giving you up to half an inch in height.
01:02:20 Too bad you become shorter by daytime, though.
01:02:24 - A rollercoaster actually tosses your organs around.
01:02:27 So when you feel like your stomach's falling down, it's actually flipping inside your
01:02:31 body.
01:02:33 - You think your fingerprints are the only unique thing in your body?
01:02:36 Well, they're not!
01:02:38 Your tongue print and your smell are also one of a kind.
01:02:42 If anyone sniffs you, it's reason enough to get suspicious.
01:02:46 - If all of your blood vessels were stretched into a single line, boy that would hurt.
01:02:52 But it would go around the Earth more than twice!
01:02:55 An impressive feat that you wouldn't see because, well, you can't live without your
01:02:59 blood vessels.
01:03:01 - You think you rest while you're asleep, but in fact, your brain doesn't.
01:03:06 It's actually more active at night than during the day, processing all the info you've collected.
01:03:12 So have some respect!
01:03:16 - The human liver is the busiest organ of the body.
01:03:19 It has over 500 functions, and not all of them are even clear to the scientists.
01:03:25 - Ever wonder why you feel so sleepy after lunch?
01:03:28 Well, that's because of your circadian rhythms, which have 24-hour cycles, demand you have
01:03:34 a nap after 7 hours of being awake, and food just adds to this effect.
01:03:40 Simple.
01:03:41 - Toothache and headache are linked together thanks to the trigeminal nerve.
01:03:46 It goes through the jaw right to the head, so when you feel tooth pain, it usually goes
01:03:51 hand in hand with that in your head.
01:03:55 - You lose calories doing literally anything.
01:03:58 A healthy 8-hour sleep, for example, makes you lose up to 800 calories.
01:04:03 And yes, you spend energy even while eating.
01:04:07 - Like all mammals, we have a diving reflex that slows down or even stops some bodily
01:04:13 functions to keep us from drowning.
01:04:16 That refers to heart rate too.
01:04:18 - A person can go without food for more than 20 days.
01:04:21 However, if you don't sleep for 10 days, your body will simply stop functioning.
01:04:27 - Talking about sleep, the average person forgets 90% of their dreams.
01:04:32 And maybe that's a good thing.
01:04:34 Otherwise, imagine how crazy the world would've been.
01:04:38 - The color of your dreams is affected by the TV you watched as a kid.
01:04:43 If you're of an older generation that watch black and white TV, you'll see monochrome
01:04:48 dreams more often than not.
01:04:51 If you're used to color television, your dreams will also be colorful.
01:04:56 - Out of every 10,000 people on Earth, one person has their organs mirrored, or reversed
01:05:02 from their usual and customary positions.
01:05:05 That is, their liver would be larger on the left side, and the right kidney would be a
01:05:09 bit superior to the left one.
01:05:12 - Speaking of kidneys, your left one is a bit more elevated than your right.
01:05:17 That's because the liver is larger on the right side of your body.
01:05:21 - People with light-colored eyes, blue or green, are better at tolerating pain than
01:05:26 those with dark eyes.
01:05:28 Scientists think it might be related to melanin that affects the color of the eyes.
01:05:33 - The length of your foot is similar to that of your forearm.
01:05:37 Don't believe me?
01:05:38 Go check!
01:05:39 I'll wait right here.
01:05:40 Nah.
01:05:42 - Not even twins have tongue prints that are alike.
01:05:45 The tongue is a movable and strong set of muscles that almost never gets tired.
01:05:50 It contains anywhere from 5,000 to 10,000 taste buds.
01:05:55 Those little white and pink bumps on your tongue aren't taste buds, but each of them
01:05:59 does have a bunch of them inside its surface tissue.
01:06:02 Evolution gave us taste buds so that we can stay alive.
01:06:06 For instance, sour and bitter flavors can be a sign that you may be eating rotten food
01:06:11 or poisonous plants.
01:06:13 The back of the tongue is more sensitive when it comes to bitter flavors, which is why we
01:06:18 can spit out bad food before we swallow it.
01:06:21 Sweetie and sweet tastes tell us if foods are rich in nutrients.
01:06:25 By the time they're 60, the majority of people lose half their taste buds.
01:06:30 Yes, your tongue is pretty cool, and its prints can be used for biometric authentication,
01:06:35 just like fingerprints.
01:06:37 Each of us have a different and unique tongue print.
01:06:40 So if you don't want to reveal your secret identity, keep your tongue hidden.
01:06:44 Huh, that would be funny.
01:06:46 Why do we even have fingerprints?
01:06:49 Scientists had a lot of different theories, but they now believe it's because having them
01:06:53 allows skin to stretch more easily.
01:06:56 That prevents blisters, protects the skin from damage, and may improve our sense of
01:07:00 touch.
01:07:01 Humans are not the only ones with unique fingerprints.
01:07:04 Koalas have them too.
01:07:07 Only around 7% of people are left-handed.
01:07:10 Left-handed people mostly chew food on the left side of their mouth, while right-handed
01:07:14 people do so on the right.
01:07:17 We lose almost 9 pounds of skin cells every year.
01:07:20 Don't worry, we replace them quickly.
01:07:23 We produce more cells than there are people living in the United States, every 15 seconds.
01:07:29 Our body is always regenerating, and we replace our skin hundreds of times during one lifetime.
01:07:35 Yep, our body regenerates, except for our teeth.
01:07:39 They're the only part of the body that can't heal itself.
01:07:42 We have teeth that are similar to a shark's.
01:07:45 Their teeth also have a thing called dentin inside of them, and theirs are just as strong
01:07:50 as ours.
01:07:51 Of course, theirs are sharper and bigger, but still.
01:07:55 Teeth are part of the human skeleton, but they're not considered bones.
01:07:59 You'll spend approximately 38 days of your life brushing your teeth.
01:08:04 And guess what?
01:08:05 It's possible to brush them too much.
01:08:08 That can make them more sensitive, because it wears down the natural enamel.
01:08:12 Our left and right lungs are not the same size.
01:08:15 The right one is bigger, because the left shares its real estate with your heart.
01:08:21 Hiccups are something almost all mammals go through from time to time, not just humans.
01:08:26 The record was set by a man named Charles Osborne.
01:08:30 He couldn't stop hiccuping for 68 years.
01:08:32 Guess no one told him about the whole eating sugar trip.
01:08:36 There's only one part of your body that doesn't get a regular delivery of blood.
01:08:40 Your corneas.
01:08:41 They get oxygen directly from the air.
01:08:44 Our eyes can differentiate between 10 million different colors.
01:08:48 The muscles that help our eyes focus on something make around 100,000 movements a day.
01:08:54 If you wanted to make your leg muscles do the same amount of work, you'd need to take
01:08:58 a long walk.
01:08:59 At least 50 miles.
01:09:01 We can't all see infrared light or ultraviolet radiation.
01:09:06 Only 1% of us can do that.
01:09:08 And if you can see one of those, it doesn't necessarily mean you can see the other.
01:09:13 Research says blue-eyed people all over the world may be related, or at least share a
01:09:18 very distant ancestor.
01:09:21 Scientists looked at blue-eyed individuals from Turkey, India, Jordan, and Scandinavia.
01:09:26 They all had the same eye color gene sequences.
01:09:29 They believe this trait comes from one blue-eyed person whose genes mutated around 10,000 years
01:09:35 ago.
01:09:36 Before that, people's eyes were just all different shades of brown.
01:09:41 People with blue eyes are generally a bit more sensitive to pain than individuals with
01:09:45 other eye colors.
01:09:47 We blink about 20 times in one minute, which means we do it more than 10 million times
01:09:53 a year.
01:09:54 That thing about being similar to sharks, well, that goes for our eyes, too.
01:09:58 If part of your eye gets damaged, you can replace it with a shark's.
01:10:03 We can't sneeze with our eyes open.
01:10:06 Try it.
01:10:07 It's really hard to override your built-in reflexes.
01:10:11 Eyelashes have their own life, too.
01:10:13 One single lash lives for about 150 days before falling out.
01:10:18 We all get goosebumps when we hear "Good News," our favorite song, or when it's ridiculously
01:10:23 cold in the frozen food aisle.
01:10:25 It's a reflex we got from our ancestors.
01:10:28 It happens when you release adrenaline.
01:10:31 It makes your hair stand on end and helps you look more imposing.
01:10:34 Rawr!
01:10:36 Scary, huh?
01:10:37 The human brain has 100 billion neurons and a memory capacity that's equal to more than
01:10:43 4 terabytes, which is a lot.
01:10:45 Your brain uses more than a quarter of all the oxygen your lungs take in, and it's mostly
01:10:50 water, more than 75%.
01:10:53 Stay hydrated, people.
01:10:55 It's not true that humans use only 10% of their brain.
01:10:59 We use much more than that, even when we're asleep.
01:11:02 Most of our brain is constantly active.
01:11:04 We just don't use all parts of it at the same time.
01:11:07 Out of all the species out there, humans are the only ones who can blush.
01:11:12 It comes from a rush of adrenaline.
01:11:14 When you see your face turn red, know that your stomach is turning red, too.
01:11:19 How weird is that?
01:11:21 When you crack your knuckles, the sound you're hearing is tiny gas bubbles being released.
01:11:26 There are pockets of gas trapped between your joints, so when you stretch them, they make
01:11:31 a popping noise.
01:11:33 Oh, so satisfying.
01:11:36 We use 43 muscles when we frown, but only 17 when we smile.
01:11:41 No scientists are still arguing over this one.
01:11:44 Say cheese.
01:11:45 An average person eats around 33 tons of food over a lifetime.
01:11:50 That's six elephants worth.
01:11:53 We breathe in approximately 2,900 gallons of air on a daily basis, but we can't swallow
01:11:59 and breathe at the same time.
01:12:02 Most people need about seven minutes to fall asleep, and we're just about the only living
01:12:06 creatures that sleep on our backs.
01:12:09 Randy Gardner decided to set the record for the longest period without sleep.
01:12:14 The year was 1964, and he stayed awake for 11 days.
01:12:18 That's 264 hours.
01:12:19 Guess he had pretty noisy neighbors.
01:12:23 Amongst all animals, humans are the only ones with chins.
01:12:27 When you're thirsty, it means the water loss you're experiencing is equal to 1% of your
01:12:32 total body weight.
01:12:34 If it goes past 5%, you might even faint.
01:12:38 During your lifespan, your body goes from having 300 bones to 206.
01:12:43 Over half of all your bones are in your feet, your ankles, hands, and wrists.
01:12:49 The biggest human bone is the thigh bone, and the smallest one is called the stirrup
01:12:53 bone.
01:12:54 It's inside your eardrum.
01:12:56 Your nose can recognize a trillion different scents and remember 50,000 of them.
01:13:02 Also, women are better smellers than men, and our sense of smell is 10,000 times more
01:13:07 sensitive than our sense of taste.
01:13:10 Our lungs have a surface area that's almost equal to the area of an entire tennis court.
01:13:15 So what's up with that feeling you get when you're going over a crest on a roller coaster
01:13:20 and your stomach jumps up into your throat?
01:13:22 Well, the seatbelt keeps your body in place, but your stomach, intestines, and smaller
01:13:27 internal organs get a little airtime.
01:13:31 It doesn't do you any harm, but your nerves can't figure out what's going on.
01:13:35 They really think your stomach has jumped all the way into your throat.
01:13:39 We're all taller in the morning because throughout the day, the cartilage between our bones gets
01:13:45 compressed.
01:13:46 That makes us around one fingernail shorter by the end of each day.
01:13:50 Ears and ears, parts of our body that never stop growing.
01:13:54 It's mostly thanks to gravity.
01:13:56 The veins and arteries inside your body are long enough to make two trips around the world.
01:14:01 Blood makes up about 8% of your body weight.
01:14:05 When you listen to music, your heartbeat syncs with the general vibe of the song.
01:14:09 So choose wisely.
01:14:11 Your skin is the biggest organ you have.
01:14:14 It counts for about 15% of your total weight.
01:14:17 Like this, you can burn more calories during sleep than when watching TV.
01:14:22 Hmm, then what about sleeping while the TV's still on?
01:14:28 You can't recall a memory all by itself.
01:14:31 When you're trying to think of one detail, like the color of the t-shirt your friend
01:14:34 was wearing the other week, you'll remember some other details too.
01:14:38 For example, the place where you saw him, things you were talking about.
01:14:43 The hippocampus is the part of your brain that stores memories.
01:14:47 It usually packs them together, including multiple small details.
01:14:52 On average, taste buds last 10 days, clusters of sensory cells in your tongue.
01:14:57 The buds that are closer to the surface are more short-lived.
01:15:01 That's the reason you don't have to wait for too long to be able to taste again after burning
01:15:04 your tongue.
01:15:07 One theory says deja vu is some sort of a brain processing lag.
01:15:12 Scientists think it might happen when your brain is transferring information from one
01:15:15 side to the other, and there's a split-second delay in that process.
01:15:20 That means that your brain gets the same information twice and processes it as the event that happened
01:15:25 before.
01:15:27 Only 30% of people can flare their nostrils, and one-third can bend their thumb backward.
01:15:34 Some people can produce a roaring noise in their heads.
01:15:38 All they have to do is tense their ears or jaws.
01:15:41 There's a small muscle in the ear; it dampens loud sounds, like when you're chewing.
01:15:46 But some people can flex that muscle, and that creates an audible rumble.
01:15:52 Your fingertips are sensitive, but hundreds of times less so than your lips.
01:15:58 You inhale lots of different types of debris, including 700,000 of your own skin flakes,
01:16:03 and that's only in a day.
01:16:07 A hypnic jerk is a twitch you can experience when falling asleep.
01:16:11 It's an abrupt muscle movement that comes during the non-REM sleep phase.
01:16:15 It can create an illusion of falling.
01:16:19 One of the theories is that, when you're dozing off, your brain sees the relaxing of your
01:16:23 muscles as a sign you're in trouble and really falling, so it sends signals to the muscles
01:16:28 to protect you by tensing up.
01:16:32 Tinnitus is a special and rare ability where people can taste music or hear colors.
01:16:37 Only one in every 2,000 people has it.
01:16:42 For some people, cilantro may taste similar to soap because the plant contains a chemical
01:16:46 used in soap making.
01:16:48 But only 4 to 14% of the world's population have special genes that can detect it.
01:16:54 18% of people can move both ears at the same time, while 22% can move one ear at once.
01:17:02 People who do it use weak vestigial muscles we got from the ancestor humans, who had this
01:17:07 in common with cats.
01:17:10 Bruises change their color over time.
01:17:12 A bruise appears because there's bleeding under the skin.
01:17:15 Tiny blood vessels get crushed, and some blood gets trapped in there.
01:17:19 In the beginning, a bruise is red because the blood is rich in oxygen, but then it turns
01:17:24 purple, green, yellow, or even gray when the levels of oxygen drop.
01:17:30 It doesn't smell itself.
01:17:32 The unpleasant odor is caused by bacteria on your skin.
01:17:36 When sweat comes out of the pores on your body, the bacteria breaks it down into acids.
01:17:41 What most deodorants actually do is get rid of the bacteria on your skin.
01:17:46 People used to dream in black and white much more than today.
01:17:49 That's because they watched black and white TV.
01:17:53 Blue cheese is another thing that affects your dreams and makes them more vivid.
01:17:58 Eggshells might be used for growing new human bones.
01:18:02 Chicken eggshells contain calcium carbonate, which is something you also have in your bones.
01:18:08 The food on the plane is likely to taste different than on the ground.
01:18:11 That's because you lose up to 30% of your tastebud sensitivity due to the dryness and
01:18:16 pressure in the cabin.
01:18:18 It's especially true about salty and sweet foods.
01:18:22 Your nostrils don't work with the same efficiency all the time.
01:18:25 When you breathe, one nostril does most of the work, and they switch every couple of
01:18:29 hours.
01:18:31 You wouldn't be able to taste food without saliva.
01:18:34 Your taste buds have chemoreceptors that recognize different flavors, but they need some liquid
01:18:38 for those flavors to bind into their molecules.
01:18:41 Also, you can't taste things saliva doesn't dissolve.
01:18:46 The brain can't actually feel pain.
01:18:49 It does have a pain center, but it doesn't have pain receptors itself.
01:18:53 When your head hurts, you can feel it because of the nerves, tissues, and blood vessels
01:18:57 around your brain.
01:19:00 A single human hair can support 3.5 ounces of weight.
01:19:03 That's how much two candy bars weigh.
01:19:07 Toenails grow almost four times more slowly than fingernails that get more exposure, and
01:19:12 are used more frequently.
01:19:14 There must be at least some photos where you have red eyes.
01:19:17 When the camera's flash goes off, your eyes aren't prepared for such an influx of light.
01:19:22 Your pupils remain dilated, which is why the light gets reflected off the red blood vessels
01:19:26 of the choroid.
01:19:28 This is a layer of tissue at the back of your eye that nourishes your retina.
01:19:33 The right lung is bigger than the left one because your body needs to make some room
01:19:36 for the heart.
01:19:38 Your teeth are the only part of your body that can heal itself.
01:19:43 The masseter is the strongest muscle you have, based on its weight.
01:19:47 Together with the rest of the raw muscles, it can close your teeth with a force of 200
01:19:51 pounds on the molars and 55 pounds on the incisors.
01:19:57 Onions produce a special chemical irritant.
01:20:00 It stimulates special glands in your eyes, causing them to release tears.
01:20:05 Your nose can memorize up to 50,000 different scents and detect more than one trillion of
01:20:10 odors.
01:20:12 We all have our unique smell, except for identical twins.
01:20:16 This smell is partly determined by genetics, but it also depends on your diet, hygiene,
01:20:21 and the environment.
01:20:24 Eating snow is not the best way to stay hydrated.
01:20:26 Your body needs too much energy to turn it into water.
01:20:30 Snow can provide a bit of hydration, but it'll also lower the temperature of your body, which
01:20:35 isn't the best scenario if you're trying to survive harsh winter conditions.
01:20:40 You burn somewhere between 100 and 200 calories per hour while standing.
01:20:45 Sitting burns 60 to 130 calories, depending on your height, weight, gender, and age.
01:20:53 Brain freeze is an annoying ice cream headache.
01:20:56 That's how your brain tells you to slow down and maybe stop eating something that's so
01:21:00 cold.
01:21:01 The main purpose of eyelashes is to shield your eyes and protect them from sand, moisture,
01:21:06 dust, and debris in the air.
01:21:08 Your eyelashes sense when something comes up too close to your eyes, like an insect
01:21:12 flying toward you.
01:21:14 And trigger your blink reflex.
01:21:16 Blinking also helps when you need to flush out some tiny particles or debris stuck in
01:21:20 your punk dot.
01:21:21 Those are small openings you have in your eyelids.
01:21:24 That's where the tears get pumped out.
01:21:27 Your eyebrows stop sweat from running directly into your eyes.
01:21:31 Your skin there, and the shape of your bones also work together to direct the sweat toward
01:21:35 the sides of your face.
01:21:38 We're not the fastest, strongest, or biggest in the animal kingdom, but we're the best
01:21:42 at long-distance running.
01:21:44 That's because we have long legs, and our bodies can lose excess heat through sweating.
01:21:49 Even long ago, our ancestors hunted animals by chasing them for long periods of time.
01:21:54 Eventually, it wore smaller creatures out.
01:21:58 Five basic senses are taste, touch, sight, sound, and smell.
01:22:03 But people have more senses than that.
01:22:06 Proprioception is when your body is aware of its parts and their position, even if you
01:22:10 don't see them.
01:22:11 Like if your arm is behind your back, you know it's there.
01:22:14 If you were an octopus, you wouldn't know it, because these creatures don't know their
01:22:18 arms exist if they can't see them.
01:22:20 Thermoception is your ability to sense temperature.
01:22:24 Equilibrioception is a sense of balance.
01:22:26 You also have gnosisception, which means you can feel pain.
01:22:30 Then there's chronoception.
01:22:32 That's how you can sense time passing by.
01:22:35 There are even more senses found in the animal kingdom.
01:22:38 Electroreception and magnetoreception.
01:22:41 But people don't have those.
01:22:44 You can't see your taste buds.
01:22:46 Those little bumps on the tongue are lingual papillae.
01:22:49 There are four kinds of them.
01:22:51 Circumvalate, foliate, fungiform, filiform.
01:22:56 They are all covered with taste buds, except for the last one, filiform.
01:23:00 This one is responsible for the sense of touch in your tongue.
01:23:05 Your pinky holds 50% of the total strength in your hand.
01:23:10 Your liver is a very important organ that works a lot and is responsible for 500 individual
01:23:15 functions.
01:23:16 Up to 10% of it is made of fat.
01:23:19 The liver can regenerate.
01:23:22 You can burn calories when you take a hot bath, as many as you would if you took a half-hour
01:23:27 walk.
01:23:29 People mostly need 7 minutes to fall asleep.
01:23:31 This time gets shorter if you've just had a large, tasty meal.
01:23:36 On average, the heart is as big as your fist.
01:23:39 It beats 115,000 times and pumps around 2,000 gallons of blood a day.
01:23:46 Ay-yi-yi, about 6% of people can vibrate and rapidly shake their eyeballs back and forth.
01:23:54 It doesn't mean something's not right with their eyes.
01:23:57 It's just a unique trick they can perform.
01:23:59 Good at parties, I suppose.
01:24:01 Your bones are designed to be used a lot daily, and some of them can absorb two or even three
01:24:06 times your body weight.
01:24:07 That's impressive, but your teeth are even stronger.
01:24:11 When you bite something, the teeth can exert incredible pressure, up to 200 pounds.
01:24:16 By the way, the enamel is considered to be part of your skeletal system.
01:24:20 Your stomach has a pretty incredible capacity, being able to hold up to half a gallon of
01:24:25 liquid, a whole large bottle of Coke.
01:24:28 It's pretty hard to estimate how much hard food you can squeeze into your stomach, since
01:24:32 the food is processed with your teeth before it gets inside.
01:24:35 There's definitely not enough room for a turkey, but a good-sized chicken will probably
01:24:40 fit it.
01:24:41 Whenever you rotate your hand, the bones inside it actually intersect.
01:24:46 Grab your hand and verify it.
01:24:48 Not very useful.
01:24:50 Show me where your stomach is.
01:24:52 If you're pointing at your tummy, sorry, but it's wrong.
01:24:55 It's up here, hidden between your ribs.
01:24:58 Fun fact about bones.
01:25:00 You know that your body is about 60% wider, right?
01:25:03 What's new here is that your bones are in this too.
01:25:06 About 25% of the human bone mass is made up of water.
01:25:10 Scientists believe that the appendix isn't here to stay.
01:25:13 Nobody really knows why we need it, but some researchers claim it helped our ancestors
01:25:18 process the tree bark they were eating.
01:25:20 As it's no longer part of our daily diet, the appendix can disappear from our bodies
01:25:25 without any consequences.
01:25:27 A human eye has some resemblance to a car engine.
01:25:30 They both need various liquids to perform properly.
01:25:33 An engine needs gasoline, and an eye needs tears.
01:25:36 In order to work well, the tears should be thoroughly distributed all over the eye.
01:25:41 That's why we blink up to 20,000 times a day.
01:25:44 So a lid is a bit of a windshield washer.
01:25:47 Almost all of our body is covered with hairs, even if we don't notice them.
01:25:51 They grow even in the belly button.
01:25:54 Their purpose is to catch lint.
01:25:56 The only part of the human body that doesn't get any nutrients from blood is the cornea
01:26:00 of the eye.
01:26:01 Instead, it's fed by tears and fluid in the front of your eyes.
01:26:05 If you never knew you had a personal bodyguard, look deeper.
01:26:10 Your liver is your security guard, protecting you from toxins and many other things you
01:26:14 don't want to have.
01:26:15 It's also pretty indestructible and can even regenerate.
01:26:19 When you blush, it means there's an increased blood flow in your body.
01:26:23 Not only do your cheeks get somewhat red, but your stomach lining too.
01:26:27 It's because it has plenty of blood vessels, and when there's more blood than usual,
01:26:32 it turns red.
01:26:33 Only about 43% of you is actually you.
01:26:36 You're over 50% tiny little creatures that mainly live in your gut and other body parts
01:26:42 without ever leaving it.
01:26:43 Still, even though your own cells are fewer than microbial ones, there are, on average,
01:26:48 about 100 trillion of them in you.
01:26:51 Let's count 'em.
01:26:52 You start.
01:26:53 Your stomach has a lining replaced every 3-4 days.
01:26:57 That's done to stop it from eating itself.
01:27:00 The digestive acids we've got can be pretty damaging.
01:27:03 One thing that surely rests while you're sleeping is your nose.
01:27:07 You just won't smell anything nasty in your sleep.
01:27:09 The thing is that your sense of smell basically deactivates at night.
01:27:14 If there's some really terrible smell in your bedroom, you won't even be bothered.
01:27:18 We can accidentally digest small objects, such as plastic items, glass, coins, and many
01:27:23 other small objects.
01:27:25 They pass their way through the digestive tract within 48 hours.
01:27:29 Really.
01:27:30 Just trust me on this one.
01:27:31 You have better things to do.
01:27:33 Scientists used to believe we could distinguish about 10,000 smells.
01:27:36 Nope.
01:27:37 Recent research showed that people were able to distinguish more than a trillion smells.
01:27:42 We also remember them better than anything else, and smells can even evoke some distant
01:27:47 memories.
01:27:48 We can digest tiny quantities of plastic, but the human digestive system can't really
01:27:53 bear grass.
01:27:55 Grazing animals have special teeth and several stomachs to process raw leaves and grass,
01:28:00 while we have none of that stuff.
01:28:02 But don't feel bad!
01:28:03 Among mammals, only humans can always walk on two hind limbs and keep that posture for
01:28:08 their entire lives.
01:28:10 You might object that kangaroos or gorillas move in the same way, but the roos use their
01:28:14 tail as a third leg, and gorillas use the help of their long arms to keep balance.
01:28:20 The stomach is the most important defender of the immune system.
01:28:23 Hydrochloric acid in our stomach kills dangerous food toxins, viruses, and bacteria that get
01:28:29 in there with the food you eat.
01:28:31 This acid can digest even the stomach itself, but the mucous membrane protects it.
01:28:36 Body fat isn't just a nuisance.
01:28:38 It acts as insulation material, energy reserve, and shock absorber.
01:28:43 Your body sends the most fat into your waist region because that's where your internal
01:28:47 organs are.
01:28:48 If something happens to you, this layer of fat might as well protect your vitals from
01:28:52 irreparable damage.
01:28:53 We've got two really fast muscles – they control the eyelid closing.
01:28:58 These are the fastest muscles in our body.
01:29:01 Eyes are fragile and need protection.
01:29:02 That's why, when the reflex is triggered, these muscles shut the eyes within about 100
01:29:08 milliseconds.
01:29:09 That's not more than 0.1 second!
01:29:12 We recognize only purple-blue, green-yellow, and yellow-red colors.
01:29:16 Everything else is a combination of these three.
01:29:19 It's impossible to calculate how many of these combinations the human eye sees because
01:29:23 every person has slight visual differences, but it's about 1 million combinations on
01:29:28 average.
01:29:30 Even if you brush your teeth twice a day and never forget about mouthwash, your mouth still
01:29:34 stays one of the dirtiest parts of the human body.
01:29:39 Millions of bacteria live inside it.
01:29:41 The good news is that most of these bacteria are good for the body and protect it from
01:29:45 bad bacteria and viruses.
01:29:48 The second dirtiest place is the belly button, and it's probably because it's the first
01:29:52 ignored place.
01:29:54 The thing is, we don't really use them after we're born, so this forlorn area accumulates
01:29:59 all kinds of germs, sweat, and dirt.
01:30:02 The belly button has over 2,300 bacterial species, and it does need extra attention.
01:30:09 You think you owe your strong handshake to all your strength workouts?
01:30:12 Well, you're more likely to owe it to your pinky.
01:30:15 Just kidding.
01:30:16 Anyway, a pinky is the strongest finger out there.
01:30:20 This humble finger is responsible for 50% of your hand strength.
01:30:23 Still, the most used finger is the thumb.
01:30:27 It takes to itself 40% of the hand's action.
01:30:30 Well, it probably makes it the most important finger too.
01:30:33 Two more humble helpers are your toes that carry about 40% of your weight.
01:30:38 If you've ever heard that humans don't really need their toes, don't believe it.
01:30:42 They're also the main pushers when you walk.
01:30:45 Tomatoes have more genes than humans.
01:30:48 This shouldn't concern you, though, because it's not the number of genes that matters,
01:30:52 but the complexity of their connections.
01:30:55 Nails don't only help us catch random objects and peel the stickers off.
01:30:59 If you didn't have a rigid structure against which to press, you wouldn't be able to judge
01:31:03 how firmly to hold anything.
01:31:06 Our hair color is easily explained by genes.
01:31:09 There are not more than 2% of people with naturally red hair.
01:31:12 They're followed by blondes, about 3%.
01:31:15 And all the varieties of brown shades, only about 11%.
01:31:19 The vast majority goes to black hair, including very dark brown.
01:31:24 Yeah, your hair can stop growing at a certain length.
01:31:27 A hair usually grows from 2 to 7 years, so usually it doesn't exceed 42 inches.
01:31:33 Well, tell that to this gal from China who broke all the hair records with the longest
01:31:38 hair ever.
01:31:39 In 2004, her hair was 18 feet 5.5 inches long.
01:31:44 Rapunzel, where have you been, girl?
01:31:47 When we laugh, think, look at something, dream, move, or do some other activity with our body,
01:31:52 small electrical and chemical signals run between neurons along those connections.
01:31:57 Our brain is always active, sometimes even more when we're sleeping than when we're
01:32:02 awake.
01:32:03 And by that, neurons make and send more information than all the phones in the whole world.
01:32:08 You're sitting somewhere outside, and an insect lands on your leg.
01:32:12 Your skin has sensory neurons, and they quickly send the message to your brain at an impressive
01:32:17 speed – 150 mph.
01:32:20 The brain sends back the message to your leg to shake the insect off very fast.
01:32:25 And the speed that information travels is even bigger – 200 mph.
01:32:30 Toenails grow around 4 times slower than your fingernails.
01:32:34 This happens because we do more things with our hands compared to feet, which is why we
01:32:38 cause more trauma to our fingernails.
01:32:40 There's a high possibility your right hand has different types of microbes than the left
01:32:46 one.
01:32:47 This happens because they cover our skin from head to toe, and their variety depends on
01:32:51 our skin thickness, humidity, temperature, texture, and chemistry, which can change as
01:32:56 we use our right and left hands in different ways.
01:33:00 Our nails and hair are made of keratin, which is a material we find in certain body parts
01:33:05 of some other animals as well.
01:33:07 For instance, claws, hooves, horns, wool, fur, feathers, beaks, turtle shells, and porcupine
01:33:13 quills.
01:33:15 Our body is made of stardust.
01:33:17 Really!
01:33:18 The more complex elements in our body can only come about through supernovas.
01:33:23 The first stars were just gassy lumps that were drawn together and, at some point, started
01:33:28 the process of combustion.
01:33:30 This finally led to a nuclear reaction in its center.
01:33:34 Stars that were there right after the Big Bang were over 50 times bigger than our Sun
01:33:37 is now.
01:33:39 Inside of them, there was a constant process of making the elements, and those large stars
01:33:43 were burning their fuel faster.
01:33:46 Most of the elements in the human body were formed in those stars over billions of years,
01:33:50 so you could realistically say that part of you is immortal.
01:33:54 Cool, huh?
01:33:55 The cornea is the only part of your body with living cells that doesn't have blood
01:34:03 vessels.
01:34:04 It gets nutrients and oxygen directly from the tear fluid on the outside, and the thick
01:34:10 watery substance you have between the cornea on the inside, and also from the nerve fibers
01:34:16 connected to the cornea.
01:34:18 That's why contact lenses used to be a potential issue.
01:34:22 The older ones were reducing oxygen supply, since the cornea mostly gets oxygen from the
01:34:27 outside.
01:34:28 This problem was solved, or at least reduced, when silicone hydrogel lenses came to the
01:34:34 market.
01:34:35 Some other parts of your body with no blood vessels are your nails, hair, outer skin layers,
01:34:41 and tooth enamel.
01:34:43 Did you notice your sweat sometimes smells of onions after your workout?
01:34:48 You have nothing to worry about.
01:34:50 There are two types of sweat glands in your skin.
01:34:53 The first kind of glands are located on certain areas of your body, like the groin region
01:34:58 and the armpits.
01:35:00 They produce a specific oily fluid, which is a response to certain emotional experiences.
01:35:06 Another type of sweat gland is way more common.
01:35:09 They're distributed all over your body, and are responsible for the specific sweat you
01:35:13 get after the workout.
01:35:16 The sweat cools your body down as it evaporates from your skin.
01:35:20 It's 99% water, so it's practically odorless.
01:35:23 Well, at least when it first leaves the pores and comes to the surface of your skin.
01:35:29 But there are many types of bacteria on the human skin, and they feed on the nutrients
01:35:34 in that sweat, together with skin flakes.
01:35:37 One of the byproducts of this is specific chemicals, and their smell can sometimes strongly
01:35:41 remind you of onion.
01:35:44 You may have noticed you produce more saliva when you go for a run, especially if it's
01:35:49 a short jog in cold weather.
01:35:52 But if you're running a marathon, and it's a nice warm day outside, you'll produce less
01:35:57 saliva.
01:35:58 It's your body trying to offset the drying effect, since you breathe through your mouth
01:36:03 way more.
01:36:06 But your body becomes more dehydrated over longer periods, which is why it's trying
01:36:11 to conserve water by reducing saliva production.
01:36:15 Every training you do, no matter how intensive it is, also makes you secrete more of a specific
01:36:20 type of protein.
01:36:22 It makes the saliva more viscous and sticky, which is why you may feel like your mouth
01:36:27 is dry way more after your workout.
01:36:31 Humans see the world 15 seconds out of date, which means your brain constantly keeps you
01:36:36 a little bit in the past.
01:36:39 This way, it helps you stabilize your vision of the world around you.
01:36:43 Your eyes receive a huge amount of visual information.
01:36:46 Yep, literally millions of colors, shapes, and ever-changing motion wherever you turn.
01:36:53 It's not an easy task for your brain to process all that.
01:36:56 The visual world alters all the time because of changes in viewpoint, light, and the rest
01:37:02 of the outer factors.
01:37:04 Your visual input changes because you need to blink.
01:37:07 Plus, your head, eyes, and your entire body are always in some sort of motion.
01:37:14 Your brain has to establish a mechanism that can create illusory stability.
01:37:19 It automatically smooths your visual input.
01:37:22 It doesn't analyze every little visual snapshot.
01:37:25 It's like a time machine.
01:37:28 You actually perceive an average of things you saw in the past 15 seconds at any given
01:37:33 moment.
01:37:34 The brain pulls together objects so they appear more similar to each other.
01:37:38 That's why it tricks you into believing you're in stable surroundings.
01:37:42 If your brain kept you updated in real time, the world would feel like a very, very chaotic
01:37:47 place with constant changes in movement, light, and shadow, which would probably feel like
01:37:53 you were hallucinating all the time.
01:37:57 Your bones are really strong, but your teeth, which we also consider as part of the skeletal
01:38:02 system, are even stronger.
01:38:05 That's because of the enamel, the hard outer layer of your tooth.
01:38:09 The enamel keeps the tissue and the delicate nerves inside your teeth safe.
01:38:15 You're basically burning calories while you're thinking.
01:38:18 When you rest and don't engage in any particular activity, except for the basics, which includes
01:38:23 digesting, breathing, and keeping yourself warm, it's the stage where your brain uses
01:38:29 up to 20-25% of the total energy of your body.
01:38:34 That means your body will burn around 350-450 calories per day while pretty much doing nothing.
01:38:42 We're not the only ones in the animal kingdom with such a mechanism.
01:38:46 Some small mammals like the minuscule pygmy marmoset and the tiny tree shrew devote the
01:38:51 same percentage of their total body energy to their brain.
01:38:56 Most of the energy the brain burns is to help its cells, the neurons, to communicate with
01:39:01 each other.
01:39:02 They do it via chemical signals the brain transmits across synapses, those special cell
01:39:07 structures.
01:39:08 So, the brain directs a lot of energy towards synapses in order to make them work.
01:39:14 Your brain never really rests.
01:39:17 Even when you're sleeping, certain parts are active.
01:39:19 So, your brain needs its fuel to work, and you're basically burning calories in your
01:39:24 sleep.
01:39:26 The more demanding mental tasks you take throughout the day, the more calories you burn.
01:39:31 So, if you skipped today's workout, solve some Sudoku!
01:39:37 Do you like to rush with your ice cream?
01:39:39 Sometimes it pays off, but if you do it often, you must know the feeling of brain freeze
01:39:44 pretty well.
01:39:46 It's a pretty intense and uncomfortable feeling that comes from the front or sides of your
01:39:51 head right after you drink or eat something cold, such as a slushy drink, ice cream, or
01:39:57 an ice pop.
01:39:59 Some people even go through a similar sensation whenever they're exposed to cold air.
01:40:04 Scientists are still not sure exactly why this happens, but one of the theories is the
01:40:09 cold substance stimulates a cluster of nerves located at the back of the palate.
01:40:14 Another theory says the blood vessels in the roof of the mouth and sinuses quickly constrict
01:40:20 because the temperature in your mouth drops before they dilate again.
01:40:24 Brain freeze is not something dangerous that you should be seriously worried about, and
01:40:29 no, hanging over the table, groaning, or clasping your head in your hands won't help much.
01:40:36 Some people like to sleep a lot.
01:40:38 Hey, guilty as charged!
01:40:41 But some have a certain condition called familiar natural short sleepers, which means they're
01:40:46 kind of immune to sleep deprivation.
01:40:49 About 1% of our population has it.
01:40:52 They can fall short on sleep and feel pretty good about it.
01:40:56 They're fine with sleeping for 6 hours per night.
01:40:59 This amount would wreck the majority of people after a couple of nights.
01:41:04 The human eye normally has three cones.
01:41:07 That means we can recognize approximately a million different shades in the green, red,
01:41:11 and blue spectrums of colors.
01:41:14 But there are some people with a rare condition, so-called tetrachromats, that have four cones
01:41:19 in their eyes.
01:41:21 This allows them to see ultraviolet shades, which means they can distinguish 100 million
01:41:26 distinct colors.
01:41:29 Did you know your skeleton is all wet?
01:41:31 I mean, your entire body mostly consists of water, up to 60%.
01:41:36 That fluid is not only in your organs, muscles, and skin.
01:41:40 It's in your skeleton, too.
01:41:42 Your bone mass is almost one-third water.
01:41:46 There's this amazing hidden network a human body holds inside.
01:41:50 Blood vessels are really small, but if you could line them all up, you'd get something
01:41:54 huge.
01:41:55 Your entire body boasts a network of 60,000 miles of blood vessels.
01:42:01 One of the ways to keep your network healthy is by eating right.
01:42:05 Have you ever wondered why our distant relatives, the primates, are so much stronger than us?
01:42:11 In many ways, our bodies are very similar.
01:42:14 Look at the chimp's muscle structure, for example.
01:42:17 But our closest primate relatives are approximately 1.35 times stronger than us.
01:42:23 The human body developed more slow-twitch muscle fibers compared to the rest of the
01:42:28 primates.
01:42:29 This type of muscle fiber is a less powerful one, but it lets us endure more than other
01:42:34 primates, and do things like foraging and hunting, activities that helped our distant
01:42:39 ancestors to survive.
01:42:42 That's also the reason why we can run a marathon.
01:42:44 A monkey could never do it.
01:42:47 But we'd still lose in a strength competition.
01:42:51 Laughter is contagious.
01:42:52 It's not just a metaphor.
01:42:55 Researchers have found that strong emotions can make the brain activity of different people
01:42:59 sink.
01:43:01 Laughter is something science usually links with social creatures.
01:43:05 People are almost 30 times more likely to laugh when in some social situations, hanging
01:43:10 out with their friends or people they feel relaxed with.
01:43:13 One of the theories says that you're probably going to join when you see your friend laughing
01:43:17 because humans are empathetic beings.
01:43:21 Your brain will release endorphins when you're laughing.
01:43:23 These are special chemicals that make you feel safe and at ease.
01:43:27 So we're not sure why exactly our laughter is contagious, but it feels really good, so
01:43:32 …. Join us on the Bright Side of life and laugh away!
01:43:41 Alright, quick question.
01:43:45 Do you think you know everything about your own body?
01:43:48 Are you sure?
01:43:49 Well, how about the fact that 25% of an adult's bones are in their feet?
01:43:54 Or that taste buds aren't actually those bumps on your tongue?
01:43:57 Well, get ready for some eye-openers!
01:43:59 No, no, we're really not going to open someone's eyes.
01:44:04 I don't do surgery here on the Bright Side.
01:44:06 Well, maybe in a future video.
01:44:08 Anyway, here we go with a big batch of biological background bots to boggle your brain.
01:44:14 Your stomach gets a new lining every 3-4 days.
01:44:17 This way, your body prevents the stomach from digesting itself.
01:44:22 Your brain contains more than 86 billion nerve cells, which are joined with one another by
01:44:27 100 trillion connections.
01:44:29 That's many more than the number of stars in our home Milky Way galaxy.
01:44:33 By the way, if you decided to count all those numerous nerve cells in your brain, it would
01:44:38 take you up to 3,000 years.
01:44:41 Better get started!
01:44:42 Your fingernails grow faster on your dominant hand.
01:44:45 In other words, if you write with your right hand, you'll have to trim those nails more
01:44:49 often.
01:44:50 Your fingernails also grow faster in the summer and during the day.
01:44:54 When your brain sends messages to different parts of your body, the signals travel along
01:44:59 your nerves at a speed of up to 270 mph.
01:45:02 It's way faster than a sports car!
01:45:06 People spend more than 4 years of their lives eating.
01:45:09 Wow, is the restaurant service that slow?
01:45:12 Just kidding!
01:45:13 The fastest muscles in your body are those that make your eyes blink.
01:45:17 Their contraction speed is one blink in less than one hundredth of a second.
01:45:22 In a day, you can blink more than 15,000 times!
01:45:26 In their lifetime, the average person processes more than 100,000 pounds of food!
01:45:31 That's more than the weight of 7 elephants combined!
01:45:34 And how do you eat an elephant?
01:45:36 Yep, one bite at a time.
01:45:38 If someone decided to uncoil the human DNA, the whole thing would stretch for 10 billion
01:45:44 miles, which is 40,000 times more than the distance between the Earth and the Moon.
01:45:49 If you don't have insomnia, you're likely to spend around one-third of your life asleep.
01:45:54 But there are creatures that sleep even more.
01:45:57 For example, for a dog, this time is 44% of their life, and for a python, 75%.
01:46:04 During just one day, all the blood in your body travels more than 12,000 miles.
01:46:09 That's half as long as the distance around Earth.
01:46:13 Your skeleton will renew itself completely within 10 years.
01:46:19 An adult uses around 200 muscles to make just one step.
01:46:23 And don't tell me I don't work out enough!
01:46:26 Every minute your body sheds more than 3,000 skin cells.
01:46:30 It's almost 200,000 skin cells per hour and more than 9 pounds per year.
01:46:35 Hey, it's the shedding skin cells weight loss plan!
01:46:39 But don't worry, you still have about 300 million skin cells at any given moment.
01:46:44 Plus, your skin completely renews itself every 28 to 30 days.
01:46:49 The liver is the only human organ that can regenerate completely.
01:46:53 As little as 25% of the original liver weight can get back to its full size.
01:46:59 Skin cells create a lot of dust, not only under your bed, but also in the Earth's
01:47:04 atmosphere.
01:47:05 If someone collected all the flaked-off skin cells floating in the air, this dust would
01:47:10 weigh up to a billion tons!
01:47:12 It's 150 times the weight of the Great Pyramid!
01:47:15 How's that for a comparison?
01:47:18 You won't see your taste buds by the naked eye because they're too tiny.
01:47:22 The small bumps most people take for taste buds are called papillae.
01:47:27 Real taste buds are on top of these hair-like projections.
01:47:30 By the way, taste buds also have a very short life cycle.
01:47:34 They live for no longer than 10 to 14 days, so they get a very short taste of life.
01:47:41 The average person has more than 100,000 hairs on their head.
01:47:45 And since this hair grows about 6 inches per year, it'll make more than 40 feet in a
01:47:50 lifetime!
01:47:51 Some people can hear their eyeballs moving inside the eye sockets.
01:47:55 That must be no fun!
01:47:57 Unlike other parts of your body, your ears and nose never stop growing.
01:48:02 That must be no fun!
01:48:05 Your skin wrinkles if you stay in the water for too long, but not because it absorbs water.
01:48:10 When your body's wet, wrinkled fingers and toes provide you with a better grip.
01:48:14 You know, like when the treads on your car tires grip the road better when they're
01:48:18 new?
01:48:19 Your eyes are an amazing instrument.
01:48:21 They can distinguish between 10 million different colors!
01:48:25 Your brain uses more than 20% of your body's energy, even when you're resting.
01:48:30 When you're asleep, it still consumes almost as much power as when you're awake.
01:48:35 It also burns about 330 calories per day at that!
01:48:39 An adult person has about 25% of all their bones in their feet.
01:48:44 Most of them are tiny but crucial.
01:48:46 If these bones are out of alignment, so is the rest of the body.
01:48:50 You breathe around 20,000 times a day.
01:48:53 Try not to stop.
01:48:55 I actually set a personal best record today for consecutive days breathing, and I plan
01:49:00 to top that tomorrow.
01:49:02 Human bones are a real paradox.
01:49:04 They're almost 5 times stronger than a steel bar with the same width, but can fracture
01:49:09 on impact and are rather brittle.
01:49:12 Fingers don't have muscles that can make them move.
01:49:15 All the muscles that move the finger joints are located in the forearm and palm.
01:49:20 Your body contains more than 37 trillion cells.
01:49:23 Earth has more than 7 billion inhabitants.
01:49:26 That means that there are over 5,000 times more cells in your body than people on our
01:49:31 planet.
01:49:32 It surely depends on your lifestyle and on how much you move, but the average person
01:49:37 will walk up to 110,000 miles in their lifetime, which is half as long as the distance from
01:49:43 Earth to the Moon, or more than 4 times longer than the distance around our planet.
01:49:48 If a person has anosmia, also called smell blindness, they can't distinguish and detect
01:49:54 smells, but they can still be smelly.
01:49:58 You start feeling thirsty when water loss is 1% of your body weight, more than 5%, and
01:50:04 you may faint.
01:50:06 Water loss is bigger than 10% of the body weight, and dehydration can end a person,
01:50:11 if you know what I mean.
01:50:13 The strongest muscle in your body, based on its weight, is your jaw muscle.
01:50:18 Mine is way overdeveloped.
01:50:20 At any moment, 50,000 cells in your body are getting replaced by new ones.
01:50:25 Boy, that sounds like a company I used to work for.
01:50:28 By the end of their life, the average person can recall up to 150 trillion pieces of information,
01:50:34 except where they left their car keys.
01:50:37 Even if fingerprints are badly damaged, they can still grow back with their original pattern.
01:50:42 Your most powerful sneeze can travel at a speed of more than 100 mph, almost as fast
01:50:48 as a skydiver in free fall.
01:50:50 The average person has about 250 hairs in each eyebrow.
01:50:54 These hairs get completely replaced every 4 months.
01:50:58 Your brain's memory capacity is equivalent to about 4 terabytes on a hard drive, which
01:51:03 is more than 8 million photos.
01:51:06 People are the only living creatures that can naturally sleep on their backs.
01:51:11 Even apes usually sleep in a sitting position, leaning on something.
01:51:16 Your longest bone is your thigh bone, not your funny bone, and the tiniest one is in
01:51:20 your ear.
01:51:21 It's shorter than a grain of rice.
01:51:23 The largest organ in your body is your skin.
01:51:27 Despite being thin, it weighs a surprising 9-11 pounds.
01:51:30 That's the weight of a healthy and well-fed house cat.
01:51:34 Your skull may feel like it's all in one piece, but in fact, it consists of 29 different
01:51:40 bones.
01:51:41 The only part of your body that can't heal itself is your teeth.
01:51:45 Ah, what a shame.
01:51:47 Right-handed people tend to chew most of their food on the right side of their mouths, while
01:51:51 the left-handed opt for the other side.
01:51:55 Out of all people who can move their ears, only 30% can move just one ear.
01:52:01 Ooh, such talent!
01:52:03 Every person has dimples on their lower back.
01:52:06 But in some people, they're more pronounced than in others.
01:52:09 These dimples appear in places where the pelvis is connected with the sacrum, so their existence
01:52:14 even if it's not apparent makes sense.
01:52:18 Your right lung is shorter than the left one because it has to leave some room for your
01:52:22 liver.
01:52:23 The left lung, on the other hand, is narrower since it has to make space for the heart.
01:52:28 A male's lungs can usually hold more air than a woman's.
01:52:32 Surprisingly, you burn more calories when you're sleeping than when you're watching
01:52:37 TV.
01:52:38 Actually, that should tell you something helpful.
01:52:41 By the time you turn 60, you're likely to lose 50% of your taste buds.
01:52:48 Your hair grows twice faster when you're traveling by plane.
01:52:51 It has to do with higher atmospheric pressure.
01:52:54 The muscles that help your eyes focus make around 100,000 movements a day.
01:52:59 If you want to make your leg muscles move as much, you'd need to walk 50 miles.
01:53:05 When you listen to music, your heart starts beating in sync with it.
01:53:09 Most people are sure that humans only have five senses, but that's not entirely true.
01:53:14 Taste, touch, smell, sight, and hearing aren't the only ones we have.
01:53:20 Scientists claim that people have between 9 and 20 senses in total.
01:53:24 These include thermoception, the sense of warmth; equilibrioception, the sense of balance.
01:53:31 There's also the sense of time, although not everyone seems to have that last one.
01:53:36 We used to think that there were just eight different blood types, but in reality, there
01:53:40 are over 30 known blood group systems.
01:53:43 Here on the Bright Side, our favorite blood group is B-positive.
01:53:47 Get it?
01:53:48 For every pound of fat you gain, you generate one mile of new blood vessels to supply oxygen
01:53:54 and nutrients to your body.
01:53:56 Your stomach produces a new lining every six days to avoid digesting itself.
01:54:02 Nerve cells transmit 1,000 nerve impulses a second.
01:54:06 They travel between 1 and 268 miles per hour.
01:54:10 Our DNA contains 100,000 viruses.
01:54:14 Scientists have discovered one that goes back 100 million years.
01:54:18 Your body emits visible light.
01:54:20 You're the brightest at 4 p.m., and your glow is the least visible at 10 a.m.
01:54:25 Unfortunately, this glowing is 1,000 times less intense than what your eyes can see.
01:54:31 Sweat is mostly water mixed with proteins, sugars, ammonia, and a lot of other stuff.
01:54:37 It even contains tiny amounts of trace metals like copper, zinc, nickel, iron, and so on.
01:54:43 What makes sweat taste salty is the sodium it contains.
01:54:47 Plus, the more salt you eat, the saltier your sweat is.
01:54:51 Your body's trying to get rid of the excess, and the fastest way is to sweat it out.
01:54:56 If you walked 2 miles per hour, you'd have to walk for 20 hours straight to lose 1 pound.
01:55:02 And it would take you 518 days and 8 hours to circle the equator.
01:55:07 Earwax isn't actually wax.
01:55:10 It contains fat, skin cells, sweat, and dirt.
01:55:14 Your brain gets three times bigger over the first year of life and reaches its full maturity
01:55:18 when you're 25.
01:55:20 60% of it is fat.
01:55:23 Your brain generates around 23 watts of electrical power, which is enough to run a small light
01:55:28 bulb.
01:55:30 Humans can't really multitask.
01:55:32 Your brain can't perform more than one action at the same time.
01:55:36 It switches between them, which doesn't save time as you might think, but increases the
01:55:41 possibility you'll do something wrong and makes the process longer.
01:55:45 When you have an exam to take or you're at work trying to focus on an important task,
01:55:50 try chewing gum.
01:55:52 Research showed it can help you stay concentrated for longer on tasks that require your full
01:55:57 attention.
01:55:58 Studies even say that it's a better test aid than caffeine.
01:56:01 There's nothing special in the gum, but the act of chewing wakes your brain up.
01:56:06 The effect doesn't last long, though, just for 20 minutes.
01:56:09 Embryos develop fingerprints at 3 months.
01:56:13 Your bones are 4 times harder than concrete.
01:56:16 The strongest bone in your body is the femur.
01:56:18 It can support up to 30 times the weight of a grown-up person.
01:56:22 Even crazier is that our bones are made up of composite material, meaning they're both
01:56:26 hard and elastic at the same time.
01:56:30 Sunburn is the result of radiation exposure.
01:56:33 When your body's natural defense mechanism gets overwhelmed trying to fight UV rays,
01:56:38 a toxic reaction occurs that results in sunburn.
01:56:41 Goosebumps are an evolutionary reflex left over from our ancestors.
01:56:46 The release of adrenaline made their hair stand up, and they look scarier to approaching
01:56:50 predators.
01:56:52 Your body produces 1 to 3 pints of saliva every day.
01:56:55 It helps you digest food and fights off infections.
01:56:59 You also have a lot of bacteria in your mouth.
01:57:01 Yeah, that's right.
01:57:02 The average amount of bacteria in a person's mouth is almost the same as the number of
01:57:06 people living on Earth.
01:57:08 That's hard to digest.
01:57:10 Each human has roughly 150,000 hairs on their head.
01:57:14 Every strand grows around one half an inch per month.
01:57:17 If we added the growth from each hair, it would measure the distance of 10 miles in
01:57:21 just one year.
01:57:23 Your hair is also a lot stronger than you think.
01:57:26 A single strand can hold 3 ounces, which is the weight of an apple.
01:57:30 If we combine the strength of all the hair on your head, it could support the weight
01:57:34 of two elephants.
01:57:35 Hey, let's try it.
01:57:37 The beating sound your heart makes is the clap of valve leaflets opening and closing.
01:57:43 Your heart doesn't replicate itself unless you have an injury.
01:57:46 Your corneas are the only part of your body that don't get blood.
01:57:50 They get oxygen directly through the air.
01:57:53 When you're sitting or standing upright, it's easier for you to recall some positive
01:57:57 memories that make you feel good.
01:57:59 Some believe it's because sitting up with your back flat boosts blood flow and your
01:58:03 brain gets more oxygen, which helps it function better.
01:58:07 The man who has the deepest voice in the world, and that's definitely not me, can produce
01:58:12 sounds that humans, including him, can't hear at all.
01:58:16 But elephants can hear those sounds.
01:58:19 Veins look blue because light has to go through layers of skin and fat to reach them.
01:58:25 Your skin scatters a lot of the red portion of white light before it reflects the blood.
01:58:30 This leaves only the blue light to bounce back to your eyes.
01:58:33 A person who has anosmia is unable to detect smells.
01:58:38 Fantasmia is the opposite condition, when someone smells an odor that isn't actually
01:58:43 there.
01:58:44 The human brain has 100 billion neurons.
01:58:47 It's 73% water, and the same is true about the heart.
01:58:51 That's why if your brain loses even 2% of its liquid, you start to feel tired.
01:58:56 It also makes your memory worse, shortens your attention span, and puts a dampener on
01:59:01 your mood.
01:59:02 The earliest known person to have had blue eyes lived in the Stone Age, 7,000 years ago.
01:59:08 Your right kidney is probably smaller and sits lower down than your left kidney to make
01:59:13 room for your liver.
01:59:15 By the way, your brain makes sure you don't drink too little or too much water.
01:59:20 After you swallow some liquid, your mouth and throat start to fire signals to your brain,
01:59:25 telling it to stop drinking.
01:59:26 Otherwise, you'd keep gulping down water for the entire 10-60 minutes it takes the
01:59:31 liquid to get to your cells.
01:59:33 Your eyes can see something for a mere 13 milliseconds, and your brain will already
01:59:38 process this image.
01:59:40 The average blink lasts from 100 to 400 milliseconds.
01:59:44 Even though the tongue isn't the strongest muscle in your body, it never gets tired.
01:59:49 That's because of the way it's built.
01:59:51 It's made up of 8 interwoven muscles.
01:59:54 The tongue is the only muscle with ends not connected to bone.
01:59:58 Other muscles join two bones at both ends because that's how we pull and make a motion.
02:00:04 There are around 700 different species of bacteria in your mouth.
02:00:08 Over 6 billion of them live there.
02:00:11 Your skin is your largest organ.
02:00:14 It can cover the surface area of two bath towels.
02:00:17 It accounts for around 16% of body weight and is around 22 square feet.
02:00:22 If you typed 60 words per minute for 8 hours a day, it would take you 50 years to type
02:00:28 the human genome.
02:00:30 You get tired pretty quickly when you're out in the heat.
02:00:33 This happens because your body is trying really hard to keep itself cool, which puts a lot
02:00:37 of extra work on it.
02:00:39 So you get exhausted and tired, even if you don't do anything physically demanding.
02:00:45 Your body has 78 organs, but only 5 of them are essential for survival.
02:00:50 The brain, liver, kidney, lungs, and heart.
02:00:53 Oh, the phone's ringing.
02:00:56 Must be something urgent.
02:00:57 At 11pm.
02:00:59 Only all the gadgets in the house are silent.
02:01:01 It's your ears that are ringing.
02:01:04 You can also hear some hissing, whistling, buzzing, and even roaring.
02:01:08 But all this noise doesn't have an external source.
02:01:12 That's why it's known as phantom sounds.
02:01:14 They can occur in one or both ears, constantly or from time to time.
02:01:19 They're usually most noticeable at night, when nothing distracts you.
02:01:23 Women have more taste buds on the surface of their tongues than men do.
02:01:27 That's one of the reasons why 35% of ladies and only 15% of guys are super tasters.
02:01:33 Those are people who feel flavors more strongly than others.
02:01:37 Left-handed people usually prefer to chew on the left side, and right-handed people,
02:01:42 well, you guessed it, chew on the right.
02:01:45 Even if your fingerprints are damaged, they'll grow back in the same unique pattern.
02:01:50 When breathing, a single lung only uses 5% of the oxygen you've inhaled.
02:01:58 There's more nerve cells and connections in your brain than there's stars in the Milky
02:02:03 Way.
02:02:04 If you decided to count them all, it'd take you 3000 years.
02:02:07 To make it easier for you, you have about 100 billion neurons in there.
02:02:12 The brain can't actually feel pain.
02:02:14 It does have a pain center, but it doesn't have pain receptors itself.
02:02:18 When your head hurts, you can feel it because of the nerves, tissue, and blood cells around
02:02:22 your brain.
02:02:24 Your RAM, or working memory, is an essential thing that we need to perform almost any everyday
02:02:29 activity, including conversations, surfing the net, and even petting your dog.
02:02:34 Our strongest and emotional memories are often fake.
02:02:38 The central memory gives us the confidence to believe that we remember everything, even
02:02:42 though most of the details are made up in our heads.
02:02:45 When we laugh, think, look at something, dream, move, or do some other activity with our body,
02:02:51 small electrical and chemical signals run between neurons along those connections.
02:02:57 And by that, neurons make and send more information than all the phones in the whole world.
02:03:04 You're sitting somewhere outside and an insect lands on your leg.
02:03:07 Your skin has sensory neurons and they quickly send the message to your brain at an impressive
02:03:11 speed, 150 miles per hour.
02:03:15 The brain sends back the message to your leg to shake the insect off very fast, and the
02:03:19 speed that information travels is even bigger, 200 miles per hour.
02:03:25 Our brain can store only 7 bits in its short-term memory.
02:03:29 Don't even try to compare your brain with a phone's capacity, not even the one you had
02:03:33 back in 2005.
02:03:35 That's why you can't even learn a phone number by heart.
02:03:38 Our short-term memory functions just like a chalkboard.
02:03:41 You can get some information, but sooner or later, you run out of space.
02:03:46 To check your working memory capacity, try this test.
02:03:49 Ask a friend to write a list of 10 words and read it to you.
02:03:53 Most people recall 7 or fewer items from the list.
02:03:58 Synesthesia is a special and rare ability when people can taste music or hear colors.
02:04:04 Only 1 in every 2,000 people has it.
02:04:08 Five basic senses are taste, touch, sight, sound, and smell, but people have more senses
02:04:15 than that.
02:04:16 Proprioception is when your body is aware of its parts and their position, even if you
02:04:21 don't see them.
02:04:22 Like if your arm is behind your back and you know it's there.
02:04:26 If you were an octopus, you wouldn't know it, because these creatures don't know their
02:04:31 arms exist if they can't see them.
02:04:33 Thermoception is your ability to sense temperature.
02:04:37 Equilibrioception is a sense of balance.
02:04:40 You also have gnosisception, which means you can feel pain.
02:04:45 Then there's chronoception.
02:04:46 That's how you can sense time passing by.
02:04:49 There are even more senses found in the animal kingdom, but people don't have those.
02:04:55 You can't recall a memory all by itself.
02:04:58 When you're trying to think of one detail, like the color of the t-shirt your friend
02:05:02 was wearing the other week, you'll remember some other details too.
02:05:05 For example, the place where you saw him, things you were talking about.
02:05:10 The hippocampus is the part of your brain that stores memories.
02:05:13 It usually packs them together, including multiple small details.
02:05:18 On average, taste buds last 10 days.
02:05:22 One theory says, "Deja vu is some sort of a brain processing lag."
02:05:27 Scientists think that it might happen when your brain is transferring information from
02:05:31 one side to the other, and there's a split-second delay in that process.
02:05:35 That means that your brain gets the same information twice and processes it as the event that happened
02:05:41 before.
02:05:42 It can create an illusion of falling.
02:05:45 One of the theories that, when you're dozing off, your brain sees the relaxing of your
02:05:49 muscles as a sign you're in trouble and really falling.
02:05:52 So it sends signals to the muscles to protect you by tensing up.
02:05:57 You can physically see your nose, but the brain chooses to ignore it.
02:06:01 Otherwise, it would stand in the way of your vision.
02:06:03 Plus, it would be out of focus.
02:06:06 Brain freeze is an annoying ice cream headache.
02:06:09 That's how your brain tells you to slow down and maybe stop eating something that's so
02:06:12 cold.
02:06:15 People mostly need 7 minutes to fall asleep.
02:06:18 This time gets shorter if you've just had a large, tasty meal.
02:06:22 People used to dream in black and white much more than today.
02:06:26 That's because they watched black and white TV.
02:06:29 Around 12% of people can't dream in color nowadays.
02:06:33 All your muscles relax at the same time, right after you've fallen asleep.
02:06:37 Your brain thinks you're about to fall asleep and sends quick signals to all of your muscles
02:06:41 to awaken them.
02:06:43 That's why it sometimes feels like you're literally falling.
02:06:46 The hypnic jerk is a twitch you can experience while falling asleep.
02:06:50 It's an abrupt muscle movement that comes during the non-REM sleep phase.
02:06:55 If you sleep, it doesn't mean all your body sleeps.
02:06:58 In fact, sometimes, your brain has to work even harder when you're asleep.
02:07:03 It needs to process tons of information, and reports usually take a lot of time.
02:07:09 By the time you wake up, you'll have forgotten 50% of your latest dream.
02:07:14 After 10 minutes, you won't remember 90% of it.
02:07:17 When you blush, your stomach lining goes red along with your face.
02:07:21 It happens because your sympathetic nervous system's causing an increased blood flow
02:07:25 throughout the body.
02:07:27 Your hair follicles have the same receptors as your nasal passages.
02:07:31 That's why your hair can detect scents, too.
02:07:33 Sandalwood can help you develop that superpower.
02:07:37 The nose definitely gets a good rest while you're sleeping.
02:07:41 Amazingly, your sense of smell basically deactivates at night.
02:07:44 You wouldn't even be bothered if there was a terrible smell in your bedroom.
02:07:48 No comment.
02:07:50 When you age, your brain is gradually reducing in size.
02:07:53 By age 75, it's much smaller than at 30.
02:07:57 And it starts shrinking by the age of 40.
02:08:00 It happens to everyone, and it doesn't affect your mental strength in any way.
02:08:04 No matter how hard you try, you'll never be able to tickle yourself.
02:08:08 It's because your brain prepares the body for tickling and helps you avoid the typical
02:08:12 laughing (I'm sorry) reaction.
02:08:16 We recognize only purple-blue, green-yellow, and yellow-red colors.
02:08:21 Everything else is a combination of these three.
02:08:24 It's impossible to calculate how many of these combinations the human eye sees, because every
02:08:29 single person has slight vision differences.
02:08:32 But it's about 1 million combinations on average.
02:08:35 You see?
02:08:38 Heads up!
02:08:40 Your skull isn't a single bone.
02:08:42 It actually consists of 28 different bones, many of which are fused together to protect
02:08:47 your brain.
02:08:48 The strongest muscles in your body aren't in your arms or legs.
02:08:52 They're in your head.
02:08:54 The masseter is the main muscle responsible for chewing, and it needs to be the strongest
02:08:58 for you to eat normally.
02:09:00 And you know those muscles that allow you to move your ears?
02:09:03 Those are temporalis.
02:09:05 Located above your temples, they also help you to chew your food.
02:09:09 Now we've got two really fast muscles.
02:09:12 They control the eyelid closing.
02:09:14 In fact, they're the fastest muscles in our body.
02:09:17 Eyes are fragile and need protection, so the reflex that protects them needs to be as fast
02:09:22 as lightning.
02:09:24 These muscles can shut the eyelids in less than a tenth of a second.
02:09:29 Our body is made of stardust.
02:09:32 Really!
02:09:33 The more complex elements in our body can only come about through supernovas.
02:09:38 The first stars were just gassy lumps that were drawn together and, at some point, started
02:09:43 the process of combustion.
02:09:46 This finally led to a nuclear reaction in its center.
02:09:49 Stars that were right there after the Big Bang were over 50 times bigger than our sun
02:09:54 is now.
02:09:56 Inside of them, there was a constant process of making the elements, and those large stars
02:10:01 were burning their fuel faster.
02:10:04 Most of the elements in the human body were formed in those stars over billions of years
02:10:08 ago.
02:10:09 So you could realistically say that part of you is immortal.
02:10:12 Cool, huh?
02:10:15 That's it for today!
02:10:16 So, hey, if you pacified your curiosity, then give the video a like and share it with your
02:10:20 friends!
02:10:21 Or, if you want more, just click on these videos and stay on the Bright Side!

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