N'est-ce pas fascinant de voir comment nos corps, ces merveilles complexes, passent souvent inaperçus dans le tumulte de notre vie quotidienne? Votre estomac peut accueillir un poulet entier ou une grande bouteille de cola. Puis il y a le foie, un gardien silencieux qui nous protège avec diligence des menaces invisibles qui se cachent dans notre environnement. Ce ne sont là que quelques facettes de l'orchestre complexe qu'est le corps humain. Peut-être qu'en reconnaissant les merveilles en nous, nous trouverons un nouveau sens de l'émerveillement pour les temples que nous habitons. Alors, embarquons dans ce voyage de découverte de soi, explorant les merveilles qui font de nos corps non pas des choses ordinaires, mais véritablement extraordinaires. Animation créée par Sympa. ---------------------------------------------------------------------------------------- Musique par Epidemic Sound https://www.epidemicsound.com Pour ne rien perdre de Sympa, abonnez-vous!: https://goo.gl/6E4Xna ---------------------------------------------------------------------------------------- Nos réseaux sociaux : Facebook: https://www.facebook.com/sympasympacom/ Instagram: https://www.instagram.com/sympa.officiel/ Stock de fichiers (photos, vidéos et autres): https://www.depositphotos.com https://www.shutterstock.com https://www.eastnews.ru ---------------------------------------------------------------------------------------- Si tu en veux encore plus, fais un tour ici: http://sympa-sympa.com
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00:00:00 Here are some facts that you may have trouble digesting.
00:00:05 Your stomach has an incredible capacity, because it can contain up to 2 liters of liquid.
00:00:12 This is equivalent to a big bottle of Coca-Cola.
00:00:16 It is difficult to assess the amount of solid food that would hold,
00:00:20 because they are crushed by your teeth before reaching your stomach.
00:00:24 There is certainly not enough room for a turkey, but a chicken should hold.
00:00:29 If you are asked where your stomach is, you may point to the middle of your stomach.
00:00:35 But it's wrong, it's here, hidden under your ribs.
00:00:40 Scientists think that the appendix will eventually disappear, no one really knows what it is for.
00:00:46 But some researchers say that it could have helped our ancestors to digest the bark of trees.
00:00:52 As it is no longer part of our diet, the appendix would therefore no longer be necessary,
00:00:57 and it can disappear from our body without any consequence.
00:01:01 The appendix is not the only obsolete part of our body.
00:01:04 Our wisdom teeth are no longer useful either.
00:01:07 They were when our ancestors lost some of their teeth.
00:01:10 But the only thing they help us lose now is the money needed to extract them.
00:01:16 Almost all of our body is covered in hair, even if we do not see them.
00:01:21 There are even in the navel, they are used to catch the fleas. Not true?
00:01:26 Your liver acts as a bodyguard, protecting you from toxins and everything you would not like to see in your body.
00:01:33 It is almost invincible and can even regenerate.
00:01:36 Only 43% of your body really belongs to you.
00:01:40 More than half of the cells in your body belong to two small creatures, mainly living in your intestines.
00:01:46 But even if your cells are inferior, you have an average of 100 billion, so you're not alone.
00:01:53 Your own genes also represent less than half of what you are really made of.
00:01:59 If we take all the living microbes in your body and add their genes, we will have between 2 and 20 million.
00:02:06 When you sleep, it does not mean that your whole body is sleeping.
00:02:10 In fact, your brain works even harder when you sleep,
00:02:13 because it processes tons of recorded information during the day.
00:02:18 Your nose, meanwhile, rests when you sleep, which means that your odor is practically deactivated at night.
00:02:25 So you wouldn't even be bothered if the worst smell entered your room.
00:02:29 It leaves you thinking. The nose is one of the most underrated parts of the body.
00:02:34 Without it, we could not even appreciate what we eat.
00:02:38 About 80% of the taste is due to the nose and its ability to recognize smells.
00:02:44 If you cover your nose while eating, you will have almost no flavor.
00:02:49 Without odor, you would recognize food just by its texture.
00:02:53 So an onion would look identical to a big sweet apple.
00:02:57 Before, scientists thought that we could distinguish about 10,000 smells.
00:03:02 But recent research has shown that we were actually able to distinguish more than a billion.
00:03:08 We memorize them better than anything else, and smells can even evoke distant memories.
00:03:14 Your nose not only helps you breathe and detect smells,
00:03:18 it also filters air for the throat and lungs.
00:03:21 By inhaling dry air, the nose moistens, refreshes or warms it up if necessary.
00:03:26 In addition, it gets rid of impurities.
00:03:29 As we age, the size of our brain decreases gradually.
00:03:33 At 75, it is much smaller than at 30.
00:03:36 And it starts to shrink at the age of 40.
00:03:39 This happens to everyone and does not affect our mental capacity.
00:03:43 The brain can only store 7 bytes in its short-term memory.
00:03:47 Do not try to compare it to the memory of a phone, even that of an old model.
00:03:52 This explains why it is so difficult to learn a number by heart.
00:03:56 Our short-term memory works like a blackboard.
00:03:59 You can remember some information, but sooner or later, you will miss two places.
00:04:04 To check it, try this test.
00:04:06 Ask a friend to write a list of 10 words and read it to you.
00:04:10 Most people remember less than 7 elements of this list.
00:04:14 Your living or working memory is an element you need to accomplish almost all your daily activities,
00:04:21 including basic conversations, browsing the Internet and even taking care of your dog.
00:04:26 Our most striking emotional memories are often erroneous.
00:04:30 Our central memory makes us believe that we remember everything,
00:04:34 even if most of the details are invented by our mind.
00:04:38 It is not only the brain that shrinks as it ages.
00:04:41 You shrink too.
00:04:43 Your bones become more fragile and your spine is compressed.
00:04:47 A similar thing happens during the night.
00:04:50 Your bones relax.
00:04:51 So when you wake up in the morning, you are taller than when you go to bed.
00:04:55 Among mammals, only humans walk on two legs all their lives.
00:05:00 We could think that kangaroos and gorillas too,
00:05:03 but kangaroos use their tails as a third leg
00:05:06 and gorillas use their arms to maintain balance.
00:05:10 Your bones also participate in your mechanism.
00:05:13 As they are mainly made of calcium, if there is not enough in your blood,
00:05:17 they release it into your bloodstream to maintain balance.
00:05:21 The same reaction also works in the opposite direction.
00:05:25 If you have too much calcium in your blood, it goes into your bones to be stored.
00:05:30 The only bone to have the sense of humor is in your arm.
00:05:34 It's the humerus.
00:05:36 Ok, it's not very funny.
00:05:38 The only bones that never grew up are in our ears.
00:05:41 We can hear thanks to these little bones,
00:05:43 which have adapted to transmit sound vibrations.
00:05:46 Doctors call them the ossicular chain.
00:05:49 One of its auditory organs, the calf, is the smallest bone in the human body.
00:05:54 It is not bigger than a grain of rice.
00:05:57 Our size, our physical characteristics and our skin color
00:06:00 depend on where our ancestors lived.
00:06:03 But we can adapt to new conditions during our own life.
00:06:07 For example, if you go to live in the mountains,
00:06:09 you will create more red blood cells to compensate for the lack of oxygen.
00:06:13 And if you go from a cold climate to a warmer and more sunny climate,
00:06:17 your skin will become darker.
00:06:20 Our lifespan is programmed in our cells.
00:06:23 They are constantly renewing.
00:06:25 But they have a kind of internal timer that stops at a given moment.
00:06:29 Some ceases to renew earlier than others.
00:06:32 On average, cells cease to divide around the age of 100.
00:06:36 If we could find a way to prevent this timer from stopping,
00:06:40 we could maybe live forever.
00:06:45 Body fat is not just a problem.
00:06:47 It also serves as an insulator, a reserve of energy and a shock absorber.
00:06:51 It is in the region of the waist that your body stores the most fat,
00:06:54 because that's where your internal organs are.
00:06:57 In case of shock, this layer of fat can protect your vital organs from irreparable damage.
00:07:03 Your skull is not made up of a single bone, but of 28 different bones,
00:07:08 most of which are welded together to protect your brain.
00:07:13 The lower jaw is the only bone in the skull that is not attached to the surrounding bone.
00:07:19 It is connected to it by conjunctive tissue and muscles.
00:07:23 That's what makes it so mobile.
00:07:26 You can move it in all directions.
00:07:29 The most powerful muscles of your body are not in your arms or legs,
00:07:34 but in your head.
00:07:36 The masseter is the main muscle responsible for chewing.
00:07:40 It must be powerful to help you eat normally.
00:07:43 And you see those muscles that help you move your ears?
00:07:47 These are temporal muscles.
00:07:49 They also help you chew.
00:07:51 We also have hyper-fast muscles that control the closure of the eyelids.
00:07:55 These are the fastest muscles of the whole body.
00:07:58 Our eyes are fragile, so the reflex that protects them must be as fast as lightning.
00:08:04 These muscles can close your eyelids in less than a tenth of a second.
00:08:09 People with double-joint thumbs can bend them backwards.
00:08:13 Very few people can do it, but it's still quite normal.
00:08:16 Even if it looks painful, it doesn't hurt someone with a double-joint thumb at all.
00:08:21 We only distinguish blue, green, yellow and red colors.
00:08:27 Everything else is a combination of these three colors.
00:08:31 It is impossible to calculate the number of combinations that the human eye can see,
00:08:35 because each person has a slightly different vision.
00:08:38 But there are on average a million combinations.
00:08:41 What to get full of?
00:08:43 Hey, listen to this!
00:08:47 You know, your bones are designed to be extremely demanding on a daily basis.
00:08:50 Some of them can absorb the force of two or even three times the weight of your body.
00:08:56 It's impressive, but your teeth are even stronger.
00:08:59 When you bite something, they can withstand an incredible pressure, up to 90.5 kg.
00:09:04 Besides, the enamel is considered to be part of your skeleton.
00:09:08 Every time you pivot your hand, the bones of your forearm cross.
00:09:12 Grab your arm and turn the apple of your hand up and down.
00:09:15 You'll see it's true.
00:09:17 Not only is your body made up of 60% water, but your bones also contain liquid.
00:09:21 About 25% of the human bone mass is made up of water.
00:09:25 The human eye has something in common with the engine of a car.
00:09:28 Both cannot function properly without various liquids.
00:09:31 The eye needs tears as much as the engine needs oil.
00:09:34 Tears must be evenly distributed over the surface of the eye.
00:09:38 That's why you blink up to 20,000 times a day.
00:09:41 And your eyelid acts as an ice cream cone.
00:09:44 The only part of the human body that doesn't receive blood nutrients is the cornea.
00:09:48 The front surface that covers the eye.
00:09:50 It is fed by tears outside and by special fluids inside.
00:09:55 When you blush, it means that the blood flow in your body increases.
00:09:59 So it's not just your cheeks, but also the wall of your stomach that turns red.
00:10:04 That's because there are a lot of blood vessels.
00:10:06 When there is more blood than usual in these vessels, the wall turns red.
00:10:10 The wall of your stomach is replaced every three or four days.
00:10:13 This prevents the organ from eating itself.
00:10:16 The digestive acids there are exceptionally powerful.
00:10:19 People can accidentally swallow small objects,
00:10:22 such as plastic coins, glass, coins and many others.
00:10:25 Normally, they do not cause any damage and pass through the digestive tube to evacuate in 48 hours.
00:10:31 Small amounts of plastic that you could accidentally consume will not hurt you.
00:10:35 But on the other hand, your stomach will have trouble digesting grass.
00:10:38 Pest animals have special teeth and stomachs to treat leaves and fresh grass.
00:10:43 But people, they, are not equipped that way.
00:10:46 But...
00:10:48 The stomach is the most important protector of the immune system.
00:10:51 It contains chlorhydric acid.
00:10:54 This acid eliminates the dangerous food toxins,
00:10:57 viruses and bacteria that accompany the food you eat.
00:11:00 The stomach itself would be digested by this powerful acid if its mucous membrane did not protect it.
00:11:06 You have two really fast muscles.
00:11:08 They control the closure of your eyelids.
00:11:10 They are the fastest of your body.
00:11:12 Your eyes are fragile and need to be protected.
00:11:14 When a particular reflex is triggered, for example,
00:11:17 when something suddenly touches your eye,
00:11:19 these muscles only need a tenth of a second to close your eyes and protect your eye.
00:11:24 Women usually clean their eyes more often than men.
00:11:27 And the older you get, the more you do it.
00:11:29 Besides, when you watch a movie with a friend,
00:11:32 you probably both blink your eyes at the same time.
00:11:35 Do you think you owe your firm hand to your muscle exercises?
00:11:38 Nope. It's thanks to your little finger.
00:11:40 I'm kidding.
00:11:41 And yet, the ear is the strongest finger that exists.
00:11:44 It is responsible for 50% of the strength of the hand.
00:11:47 But the most used finger is the thumb.
00:11:50 If a person loses it, his hand becomes 40% less agile.
00:11:53 Oh, and the thumb has its own skin, thanks to the artery that runs through it.
00:11:57 Your big toes carry more than 40% of your weight.
00:12:00 More than all the other toes combined.
00:12:02 In fact, all your toes are very important.
00:12:05 They provide support and balance when you walk.
00:12:07 And when you run, they help you be faster.
00:12:10 No more than 2% of people have natural wavy hair.
00:12:13 They are followed by blondes, about 3%, and by all kinds of shades of brown, about 11%.
00:12:18 But the most common hair colors in the world are black and French brown.
00:12:22 Hair is almost indestructible.
00:12:25 They can be burned or affected by strong acids,
00:12:27 but that's about all you can do to destroy them.
00:12:30 Your hair usually stops growing to a certain length.
00:12:33 And since a hair lives from 2 to 7 years,
00:12:36 its length normally does not exceed 106 cm.
00:12:39 Tell this lady, Xi Jinping, from China,
00:12:42 who broke the Guinness World Record for the longest hair of all time.
00:12:46 In 2004, they were 5 meters long.
00:12:48 Wow!
00:12:49 Nails can also get super long.
00:12:51 Some of the world's longest nails belonged to an Indian, Shridhar Shillal.
00:12:56 Their total length was 9 meters,
00:12:58 which is almost as long as a two-story red bus in London.
00:13:01 The man cut them in 2018.
00:13:03 Nails help us catch small objects and take off stickers.
00:13:07 But that's not all.
00:13:09 If you didn't have a rigid structure to lean on,
00:13:12 you wouldn't understand how much you have to hold things firmly.
00:13:16 Not only your hair and nails can grow, but also your liver.
00:13:19 It's the largest internal organ in terms of mass.
00:13:22 The liver can regenerate completely,
00:13:24 going from only 51% of its initial mass to its maximum size.
00:13:28 And at the same time, constant damage to the liver leads to scars.
00:13:32 The most important organ of your body is the skin.
00:13:35 It represents more than 15% of your total weight.
00:13:38 People lose 30,000 to 40,000 skin cells every minute.
00:13:42 That's up to 4 kilos of skin cells per year.
00:13:45 You know that dust in your house?
00:13:47 Well, now you know where some of it comes from.
00:13:50 The tongue is not the only organ that helps you recognize your taste.
00:13:53 Your nose also plays a crucial role in this process.
00:13:56 It is often said that the nose is responsible for 75 to 95% of the perception of taste.
00:14:01 Try to pinch your nose the next time you eat.
00:14:03 Bite into an onion or eat smoked fish.
00:14:06 It's not that you won't taste anything, but it will be much more bland.
00:14:09 Your taste buds won't work properly if your mouth is too dry.
00:14:13 You won't taste as much as long as the food isn't covered in saliva.
00:14:17 It contains enzymes, which are complex protein molecules.
00:14:20 They begin to break down your food as soon as it enters your mouth.
00:14:24 A recent study has shown that people can distinguish more than a billion smells.
00:14:28 You tend to remember smells better than sounds or images.
00:14:32 That's why smells can evoke distant memories.
00:14:35 When you sleep, you don't smell anything.
00:14:38 Basically, your sense of smell goes off at night.
00:14:41 Even if there is a terrible smell in your room, you won't notice it.
00:14:44 I'm sure my dog is relieved to hear that.
00:14:47 The color of your dreams seems to be affected by the television you watched when you were a kid.
00:14:51 If it was white-and-black most of the time, you would have monochrome dreams.
00:14:55 If you are used to colored television, your dreams will probably be colored.
00:14:59 What kind of dreams did people have in the Middle Ages?
00:15:02 Your heart can betray you when you lie, starting to beat faster.
00:15:06 Women's hearts are generally smaller than men's.
00:15:09 That's why they have to work harder and beat more.
00:15:11 Otherwise, they wouldn't be able to pump enough blood.
00:15:14 Even if you brush your teeth twice a day and never forget to bathe,
00:15:18 your mouth remains one of the dirtiest parts of your body.
00:15:21 Millions of bacteria live there.
00:15:23 The good news is that most of them are good for your health.
00:15:26 They protect your body from bad bacteria and viruses.
00:15:29 The second dirtiest part is your navel.
00:15:32 You don't really use it after you're born.
00:15:34 This neglected area accumulates all kinds of germs, sweat and dirt.
00:15:38 A navel has more than 2,300 bacterial species and requires special attention.
00:15:44 It is said that the eyes do not grow with the rest of the body.
00:15:47 But that's not 100% true because the eyes are not fully developed before the age of 21.
00:15:52 But the absolute champions of growth here are your ears and your nose.
00:15:56 They keep growing.
00:15:58 What was that thing with the elephants?
00:16:00 Ah, that must have been another video.
00:16:02 If all your blood vessels were spread out on a single line, you'd be in trouble.
00:16:07 But they would go around the Earth four times.
00:16:10 You can't do any exercise, no matter how hard you try.
00:16:14 You just checked and you failed, didn't you?
00:16:16 It's because your brain tells you that you're about to be tickled.
00:16:19 Which it can't do if it's someone else sticking to it.
00:16:22 Have you ever wondered why you fall asleep after lunch?
00:16:25 One of the reasons is your circadian rhythm, which works according to a 24-hour cycle.
00:16:29 It requires you to take a nap seven hours after you wake up.
00:16:32 And food only adds to that effect.
00:16:35 It's as simple as that.
00:16:37 Oops, sorry, it's time.
00:16:39 [snoring]
00:16:41 Your heart is the size of your fist.
00:16:45 Your brain, two fists.
00:16:48 When you listen to music, the beats of your heart synchronize with its rhythm.
00:16:53 You can't swallow and breathe at the same time.
00:16:56 Believe me on that.
00:16:58 There are as many nervous cells in your brain as there are stars in our galaxy.
00:17:02 About 100 billion.
00:17:04 You measure an extra centimetre in the morning than in the evening.
00:17:07 You can thank gravity for that.
00:17:10 That's also why astronauts become 3% taller during their stay in the gravity of space.
00:17:16 An average person breathes more than 11,000 litres of air per day,
00:17:20 which is enough to inflate 1,000 balloons.
00:17:22 Your body contains enough blood vessels to travel around the planet twice and a half.
00:17:28 You spend four months of the year sleeping.
00:17:31 In a life span of 26 years, only six of those years will be spent dreaming.
00:17:36 50% of a dream is forgotten in the five minutes that follow waking up.
00:17:40 Ten minutes later, it's 90%.
00:17:44 Here are the bad news.
00:17:46 Your nose and ears are the only parts of your body that never stop growing.
00:17:50 The human brain produces enough electricity to power a small light bulb.
00:17:55 If your eye was a digital camera, it would have a resolution of 576 megapixels.
00:18:01 The human brain could store the equivalent of 2.5 million gigaoctets,
00:18:06 which is 3 million hours of your favourite TV show.
00:18:10 Each cell in your body contains 1.5 gigaoctets of information.
00:18:14 Do the math for the 100 billion cells and you'll see that you're a powerful walking computer.
00:18:20 Your brain cools down when you're sleeping.
00:18:23 Your ears even work when you're sleeping, but your brain ignores the information that reaches it.
00:18:29 The distance between your arms is equal to your height.
00:18:33 You renew your skeleton every ten years.
00:18:35 You lose a hundred hair a day, and that's perfectly normal.
00:18:39 Humans are the only creatures that sleep on their backs for a long time.
00:18:44 Koalas, like humans, have their own digital prints.
00:18:48 The prints on your tongue are also clean, but they don't have a scanner.
00:18:53 Scientists at the University of Pittsburgh have discovered that people with blue and green eyes
00:18:58 are less sensitive to pain than people with brown eyes.
00:19:01 But light-colored eyes are more sensitive to light than dark eyes.
00:19:05 The microorganisms in the human body are ten times more numerous than these cells.
00:19:10 And all the bacteria in your body weigh about 1.8 kilograms.
00:19:15 The nail that develops the fastest is the middle one.
00:19:18 The slower, the bigger.
00:19:20 Blondes have more hair than brunettes and redheads.
00:19:24 Your ability to distinguish smells disappears when you sleep.
00:19:28 There's enough iron in your body to make a 7-centimeter nail.
00:19:32 Without the little finger, your hand would lose half its strength,
00:19:36 no matter how you lost it. Ouch!
00:19:38 People can't digest grass.
00:19:40 Cows can, because they have four stomachs.
00:19:43 The mind generates about 70,000 thoughts a day.
00:19:47 A man will grow 15 meters of beard in one life, the height of a telephone pole.
00:19:52 It takes a minute for our 5 liters of blood to circulate in the body.
00:19:57 In one life, an average person will walk three times around the world.
00:20:02 A person can have from 250 to more than 1,000 hairs per eyebrow.
00:20:07 Your eyebrows also have a lifespan of about 4 months
00:20:10 so that all the hairs fall and are replaced by new ones.
00:20:13 Phew! Luckily!
00:20:15 Your eyes are the only organ that doesn't grow with age.
00:20:18 Your body shines in the dark.
00:20:20 It's just too weak for you to see it.
00:20:23 99% of the body's calcium is in the teeth and bones.
00:20:28 The human eye can distinguish up to 10 million different colors.
00:20:32 Most people will spend four months of their lives waiting for the traffic lights to go out.
00:20:36 What a waste of time!
00:20:38 The muscles of your iris contract and stretch to determine the size of your pupils.
00:20:43 Your pupils get bigger when you look at someone who attracts you.
00:20:47 Your skin covers an area of 2 square meters.
00:20:50 The thickest skin is on the plant of your feet, the thinnest on your eyelids.
00:20:55 Your stomach blushes when you play in the background.
00:20:58 The only part of the human body that cannot recover by itself are the teeth.
00:21:03 People can have up to 7,000 different facial expressions,
00:21:06 like this one, or this one, or even this one.
00:21:10 The largest organ of the human body is the skin, which weighs 9 kilos.
00:21:15 You can't blink or breathe while you're frothing.
00:21:20 The bumps on your tongue are called "papilles."
00:21:23 Not all papilles contain taste buds, but those that do can have one to five each.
00:21:30 Your bones make up 30% of the water.
00:21:33 The atoms of your body make up 99% of the void.
00:21:37 And yet, you feel full after dinner. How does that happen?
00:21:41 The brain develops during the first 18 years of life,
00:21:44 then decreases by 5% every 10 years, after 40 years.
00:21:47 That explains a lot of things, don't you think?
00:21:50 Your stomach is usually one liter big, but it can stretch to contain 4 liters.
00:21:55 We spend 10% of our waking hours with our eyes closed, just to wink.
00:22:01 The muscles that make our fingers work are actually in our forearm.
00:22:05 Your foot is the same length as your forearm.
00:22:08 The ratio is your thumb and your nose.
00:22:11 With proper training, a single finger can support the weight of your whole body.
00:22:16 Your toenails grow three times slower than your fingernails.
00:22:20 Your lungs are not identical.
00:22:22 The one on the right has three lobes, and the one on the left has two.
00:22:25 Your hair grows faster when you sleep.
00:22:28 The only thing that grows faster than hair is the bone marrow.
00:22:32 The enamel of your teeth is the hardest tissue in your body.
00:22:35 Your bones are four times more resistant than concrete.
00:22:38 On average, a person drinks enough water during their lifetime to fill 150 jacuzzis.
00:22:44 You have a unique smell.
00:22:46 People lose half of their taste buds by the age of 60.
00:22:51 Your body releases enough heat in half an hour to boil 2 liters of water.
00:22:56 Your brain uses 20% of the energy that your body produces.
00:23:00 Your body uses more energy to cool down on hot days
00:23:03 than to warm up when it's cold.
00:23:06 People can stay much longer without food than without sleep.
00:23:10 The acid in the stomach can dissolve metals.
00:23:13 It's so strong that the stomach has to build a new wall every 3 to 4 days.
00:23:17 So what's bothering you?
00:23:19 The loudest ever recorded snoring was 93 decibels.
00:23:24 Louder than a lawnmower.
00:23:26 Yeah, I think it was in my house.
00:23:28 A single DNA molecule in a cell is 2 meters long.
00:23:32 If you could unroll all the DNA in your body,
00:23:35 it would go back to Pluto.
00:23:37 But Pluto is no longer a planet.
00:23:40 The rule of three states that the human body can spend 3 minutes without air,
00:23:44 3 days without water, and 3 weeks without food.
00:23:47 But not 3 seconds without the Internet.
00:23:49 Your brain forgets information to think faster
00:23:52 and protect itself from emotional overload.
00:23:55 Our eyes can see the flame of a candle up to 50 kilometers a clear night.
00:24:00 Human DNA is 96% like a chimpanzee's,
00:24:04 90% like a cat's,
00:24:06 70% like a lima's,
00:24:09 and 50% like a banana's.
00:24:11 It's a lot!
00:24:13 You share 99.9% of your DNA with any person on the planet.
00:24:19 A printed version of your complete genetic code would have more than 260,000 pages,
00:24:24 which represents about 200 big books.
00:24:27 In terms of muscles, your tongue is like an elephant's trunk and a peach's tentacle.
00:24:32 Uh, ok.
00:24:34 Your nails are made of the same material as a rhinoceros' horn and a horse's hooves.
00:24:39 And the rhinoceros would like to get it back.
00:24:43 We have nails to protect the tip of our fingers.
00:24:46 Without them, it would be more difficult to grasp things.
00:24:49 You use 200 muscles just to take a step,
00:24:53 and 50 muscles just to use chopsticks.
00:24:56 You use two fingers to play chopsticks on the piano.
00:25:00 The word "muscle" means "little mouse" in Latin,
00:25:03 because that's what a flared bicep looked like, according to the Romans of Antiquity.
00:25:07 The surface of the body could contain 110,000 mosquitoes at a time,
00:25:11 and feed 15 million.
00:25:13 Volunteers around here?
00:25:15 Most people pronounce about 125 words per minute.
00:25:19 The brain can process 800 at the same time.
00:25:22 I can do up to 185, with gusts of wind going up to 250.
00:25:27 Your skin is completely renewed every 27 days.
00:25:31 You can't chat. Your brain already knows your intentions and prepares your body for it.
00:25:37 Humans are the only species with a contour that separates the lips from the surrounding skin.
00:25:43 Your lips are red or pink because there are tons of hair just under their thin skin.
00:25:49 Your ears produce more human wax when you're scared.
00:25:52 I must be terrified.
00:25:54 The information travels to and from the brain at a speed of 435 km/h,
00:26:00 faster than an arrow.
00:26:02 The smallest bone and the smallest muscle in your body are both in your ear.
00:26:08 Your head weighs 4.5 kilos.
00:26:11 Your eyes breathe.
00:26:13 Well, the cornea is the only part of you that has no blood supply.
00:26:17 It receives oxygen directly from the air.
00:26:20 The cornea of sharks is so similar to that of humans that it could be used for transplantation.
00:26:26 Half of the bones in your body are in your feet and hands.
00:26:30 Come on, let's share, guys.
00:26:32 Finally, corneas have more genes than people.
00:26:35 Your cereals have 32,000. You have 20,000.
00:26:39 Wow, you'd need a very large closet to hold 20,000 jeans.
00:26:43 Uh, okay, I'm out. See you later.
00:26:48 Oh, the phone is ringing.
00:26:51 There must be something urgent at 11 p.m.
00:26:53 Except that all the gadgets in the house are silent.
00:26:56 Oh no, it's your ears that are making noise.
00:26:59 You can also hear whistling, rumbling and even rustling.
00:27:03 But all this noise does not come from an external source.
00:27:06 These are what are called ghost sounds.
00:27:08 They can occur in one or two ears, all the time or from time to time.
00:27:12 They are generally more noticeable at night when nothing distracts you.
00:27:16 The noise you hear in your ears is called acouphenia.
00:27:19 It is quite common and affects 15 to 20% of the population.
00:27:23 Acouphenia begins in the part of the inner ear that is in the shape of a snail.
00:27:26 This is what we call the cochlea.
00:27:28 Your middle ear captures the sound waves.
00:27:31 They are then translated into electric impulses in the inner ear.
00:27:35 Then the sensory nerves transmit these impulses to your brain.
00:27:38 If your inner ear is not working properly, your brain can misinterpret the sounds.
00:27:43 Acouphenia occurs when the cochlear nerve undergoes certain modifications.
00:27:47 They can be caused by loud noise, such as chainsaws, hammers, loud music or screams.
00:27:53 Acouphenia can occur after a cranial trauma, a neck injury or an ear injury,
00:27:58 or after starting to take certain drugs.
00:28:01 You can also hear ear rumbling if you have problems with arterial tension.
00:28:05 Let's go elsewhere in the incredible human body.
00:28:08 Some of the bacteria that live in the intestines can produce electricity.
00:28:12 It's crazy!
00:28:13 They emit electrons and this generates tiny electric currents.
00:28:17 It is probably the bacteria's life support system, its way of generating energy.
00:28:22 Humans are the only animals with a chin.
00:28:24 Even our closest genetic parents, gorillas and chimpanzees,
00:28:28 are deprived of this small piece of bone that protrudes from the jaw.
00:28:31 Their lower jaws are tilted down and back compared to their front teeth.
00:28:36 Scientists still don't understand this mystery.
00:28:39 Their opinions vary as to why people are so made.
00:28:42 Some researchers think that the chin helps us chew our food.
00:28:46 Others believe that they certainly have a link with speech.
00:28:50 Some of us think it's just a special place to grow a beard.
00:28:54 Hmm.
00:28:55 Winking allows you to keep it clean and moist.
00:28:58 But that's not all. Every time you wink, you're actually taking a nap.
00:29:03 Researchers at the University of Washington have found that winking
00:29:07 increases vigilance and allows you to recharge your batteries.
00:29:10 Have you ever seen tiny dots move in a sine wave,
00:29:14 especially when you look at a blue sky?
00:29:16 These dots are only visible for about a second and can look like tiny green dots.
00:29:21 These are actually your white blood cells that move in the capillaries in front of the retina.
00:29:26 It's the photosensitive tissue behind your eyes.
00:29:30 Interestingly, most people don't even pay attention to these dots,
00:29:34 unless you ask them to.
00:29:36 The pineal gland of the brain produces melatonin.
00:29:40 It's this hormone that regulates sleep.
00:29:43 The gland looks like a pine cone, and that's how it got its name.
00:29:46 The human brain is made up of 73% water, and the same goes for the heart.
00:29:51 So if your brain loses only 2% of the liquid, you start to feel tired.
00:29:57 It also deteriorates your memory, reduces your attention span, and ruins your mood.
00:30:02 By the way, your brain makes sure you don't drink too much or too little water.
00:30:07 After swallowing a liquid, your mouth and throat start to send signals to your brain
00:30:11 to tell it to stop drinking.
00:30:13 Otherwise, you'll keep swallowing water for the next 10 to 60 minutes
00:30:17 that the liquid takes to reach your cells.
00:30:20 It's enough to see something for only 13 milliseconds
00:30:23 for your brain to process that image.
00:30:26 For comparison, the average blink lasts from 100 to 400 milliseconds.
00:30:31 Even if the tongue is not the strongest muscle in your body, it never gets tired.
00:30:36 It's linked to the way it's made up.
00:30:38 It's made up of 8 interlaced muscles.
00:30:41 But unlike the other muscles in your body,
00:30:43 these are not distributed around a support bone.
00:30:46 The structure of the tongue is similar to that of an elephant's trunk or a peacock's tentacles.
00:30:51 Your body emits a visible light.
00:30:53 That's why we call it "sunny".
00:30:55 Ah, you shine the most at 4 p.m. and the least at 10 p.m.
00:30:59 Unfortunately, this glow is a thousand times less intense than what your eyes can perceive.
00:31:04 Sweat is mainly made up of water mixed with proteins, sugars, ammonia, and much more.
00:31:10 It even contains tiny traces of metals such as copper, zinc, nickel, iron, etc.
00:31:16 This gives sweat a salty taste. It's the sodium it contains.
00:31:20 Moreover, the more salt you eat, the saltier your sweat.
00:31:23 Your body tries to get rid of the excess, and the fastest way is to sweat.
00:31:28 The blood of an adult represents 7 to 8% of the total weight of your body.
00:31:32 About 55% of our blood is made up of liquid plasma.
00:31:36 The rest is made up of red, white, and platelet-rich blood cells.
00:31:39 They create pebbles and prevent bleeding.
00:31:42 You can't swallow and breathe at the same time.
00:31:44 The food you eat and the air you breathe first go down to the same part of your throat.
00:31:48 A little deeper only, the passage is divided into the esophage, for food and liquid, and the trachea, for air.
00:31:55 By swallowing, your respiratory tract automatically closes.
00:31:59 This prevents you from accidentally inhaling food.
00:32:02 But sometimes, it happens anyway.
00:32:04 Your brain sometimes generates more than 48 thoughts in a single minute.
00:32:08 That's almost 3,000 thoughts per hour and 69,000 per day.
00:32:12 Nails grow faster on the dominant hand.
00:32:15 If you often use your right hand, you will have to cut your nails more often.
00:32:19 Nails also grow faster in the summer and during the day.
00:32:22 You can memorize up to 10,000 different faces.
00:32:25 Of course, this varies from person to person, and the average number is 5,000.
00:32:29 That doesn't mean you can identify each of these faces.
00:32:32 It's just about recognizing the features.
00:32:34 If you ever feel like lying, know that your nose will always betray you.
00:32:38 When a person tells a lie, the temperature around his nose and in the inner corners of his eyes rises.
00:32:45 This phenomenon is known as the "Pinocchio effect".
00:32:48 Women have more taste buds on the surface of their tongues than men.
00:32:52 This is one of the reasons why 35% of women and only 15% of men are super-tasters.
00:32:58 These are people who feel the flavors more strongly than others.
00:33:02 Teeth are the only part of the body that cannot heal itself.
00:33:06 But the enamel they are covered with is one of the most resistant elements of the human body.
00:33:11 Your heartbeat often synchronizes with the music you listen to.
00:33:15 If a song has a continuous increase in volume or tempo, like rock, it can speed up your heart rate.
00:33:22 Some classical music lowers the heart rate and blood pressure.
00:33:26 This phenomenon affects everyone, from professional musicians to amateurs and mellowmen.
00:33:31 The human body has between 2 and 5 million sudoriparous glands.
00:33:35 The sweat they produce is of two different types.
00:33:38 Stress sweat and regular sweat.
00:33:40 Hey, don't sweat like an old pig!
00:33:42 Sweat caused by stress contains fatty acids and proteins.
00:33:46 And normal sweat is mainly composed of water, salt and a little bit of other substances.
00:33:52 It can happen when you brush your teeth too deeply and hard.
00:33:56 This can wear out the enamel and make the teeth very sensitive to cold and hot foods.
00:34:00 If you walked in the same direction 12 hours a day, it would take you about 800 days to travel the world.
00:34:06 And don't forget to wear rubber boots for when you cross the ocean.
00:34:10 If the acid in your stomach came into contact with your skin, there would be a good chance that it would make a hole.
00:34:16 All this because of the chloride acid.
00:34:18 This type of acid is incredibly powerful.
00:34:20 It can easily dissolve certain metals, such as magnesium or zinc.
00:34:24 Chloride acid is the main component of gastric acid that your stomach produces.
00:34:29 It protects our immune system and eliminates viruses and bacteria present in the food we eat.
00:34:35 This acid also helps the body to decompose, digest and absorb all kinds of nutrients, including proteins.
00:34:42 The lips are red because they contain a large concentration of miniature blood capillaries, just under the skin.
00:34:49 Your little finger is very powerful.
00:34:51 Without it, your hand would lose an important part of its strength.
00:34:54 Your index and your thumb cooperate with your thumb to grab and pinch.
00:34:58 And your ear, with your ring, ensures the strength of the grip.
00:35:02 The fattest organ in your body is your brain.
00:35:05 Fat is at least 60% of its dry weight.
00:35:09 This quality has allowed the brain to reach the Guinness World Record.
00:35:13 This organ contains about 25% of your body's cholesterol, which is vital for the well-being of the brain.
00:35:20 The cells in your skeleton keep regenerating.
00:35:24 That's why we make a new skeleton every 10 years or so.
00:35:28 This process slows down with age, and regeneration takes longer.
00:35:32 It's one of the main reasons why bones become more and more fragile.
00:35:36 A new type of brain cell, recently discovered, is crucial for visual research.
00:35:41 They are called target cells.
00:35:44 Without their help, it would be impossible to detect a knowledge in a crowd or your dog in the park.
00:35:49 It's interesting to note that target cells make fun of the appearance of the thing you're looking for.
00:35:55 All they want to know is whether an object is your target or not.
00:35:58 Hey, pretty simple, isn't it?
00:36:00 Did you know?
00:36:04 A single hair can withstand a traction of about 85 grams.
00:36:08 On average, a person has about 150,000 hairs.
00:36:11 And when your hairs are put together, they can withstand a traction of about 13 tons,
00:36:15 or the weight of two elephants, not to mention peanuts!
00:36:19 The electricity produced by your brain would be enough to light a small bulb,
00:36:23 if only you knew how to do it.
00:36:25 If you're not bad at cutting your nails or hair,
00:36:27 it's because the only living part of them is under your skin.
00:36:31 Also, our nails grow faster in summer than in winter,
00:36:33 even in places where there's not much difference between seasons.
00:36:37 And your nails grow faster on your right hand,
00:36:40 probably because you use it more often.
00:36:43 It must stimulate their growth.
00:36:45 It seems to us that our little finger is weak, but it's not true at all.
00:36:48 Without it, you would lose 50% of the strength of your hand.
00:36:51 It usually works with your ring finger to give you power.
00:36:55 The other three are more suitable for catching things.
00:36:59 Just like the tip of your fingers, your tongue has a unique footprint,
00:37:02 but you can't use it to unlock your phone.
00:37:04 At least, not yet.
00:37:06 In addition, your tongue is full of fat.
00:37:08 If you gain weight, your tongue also gains weight.
00:37:10 There's acid in your stomach, and it's used to break down food.
00:37:14 This acid is so powerful that it could make a piece of wood disappear.
00:37:17 The total length of all adult blood vessels is about 160,000 km,
00:37:22 which is four times the circumference of the equator.
00:37:25 During your life, you will produce enough saliva to fill two pools.
00:37:29 Our ancestors needed chicken meat to straighten their body hair
00:37:33 and scare their enemies.
00:37:35 We don't need it anymore, but we still have chicken meat.
00:37:38 Our evolution will make us lose this feature.
00:37:41 You probably never noticed it,
00:37:43 but most of the time you only breathe through one nostril at a time.
00:37:46 Every few hours, your nostrils connect.
00:37:48 That's why only one of your nostrils moves when you have a cold.
00:37:51 Most people think they have five senses, but that's not true.
00:37:55 Scientists are not sure yet, but they think there are more than 20.
00:37:58 There is sight, hearing, touch, smell and taste,
00:38:02 and other senses like time, hunger and thirst.
00:38:05 And then there is proprioception, the sense of your body's position in space.
00:38:09 The brain doesn't always differentiate between intense happiness and great sadness.
00:38:14 It understands that you feel a very strong emotion, but it is sometimes a little confused.
00:38:18 That's why you can cry when you're very happy.
00:38:20 Your eyes stay about the same size all your life,
00:38:22 but your nose and ears never stop growing.
00:38:24 The opposite would be really weird.
00:38:26 In the past, all humans had brown eyes.
00:38:29 Other colors developed as a result of a fortuitous mutation.
00:38:33 Scientists think that if the first humans appeared on Earth about 6 million years ago,
00:38:37 the first person with blue eyes only appeared 100,000 years ago.
00:38:41 So it's quite likely that people with blue eyes are all the same ancestor.
00:38:45 Uncle Bob!
00:38:47 All the bones of the human body are connected to each other, except one.
00:38:50 The osteoid, in the shape of an "U", is at the base of the tongue to hold it in place.
00:38:55 The bones are more resistant than steel.
00:38:57 A healthy bone could theoretically support the weight of five trucks.
00:39:00 However, it is not the strongest part of the body.
00:39:03 The strongest element is the teeth.
00:39:06 It is made of a lot of different materials that make it very resistant.
00:39:09 Teeth last a long time, several hundred years.
00:39:11 But of course, you still have to take care of them.
00:39:13 They are the only part of the body that cannot heal itself.
00:39:17 Your heart works non-stop, about 3 billion times throughout your life.
00:39:22 Just like your heart, your tongue never takes a vacation.
00:39:25 Even when you sleep, it helps to pass saliva into your throat.
00:39:28 By the way, where do you put your tongue when you rest?
00:39:30 If you keep it at the bottom of your mouth, you make a mistake.
00:39:33 This position can cause neck and jaw pain.
00:39:37 If you keep it stuck against your teeth, you're wrong too.
00:39:40 It can move your teeth and cause chewing problems.
00:39:43 Try to keep it in the middle, about a centimeter from your teeth.
00:39:47 We can't breathe and swallow at the same time.
00:39:49 The reason is that the air we breathe and the things we swallow follow the same path.
00:39:54 At least at the beginning.
00:39:55 It's like a little guy driving traffic a little further.
00:39:58 Your eyes breathe too.
00:40:00 The cornea is the only part of the body that has no direct blood supply.
00:40:03 It receives its oxygen directly from the air.
00:40:05 That's why your eyes are irritated when it's dry outside.
00:40:08 Everyone dreams.
00:40:11 If some people say they never dreamed once in their life,
00:40:14 it's just that they never remember their dreams.
00:40:17 Some scientists think that the dream stage is followed by an active forgetfulness stage.
00:40:20 Probably because the information contained in our dreams is not really important.
00:40:24 Our brain is economical.
00:40:26 It makes room for useful things.
00:40:28 Those who are lucky enough to remember their dreams
00:40:30 end up forgetting half of it in the five minutes that follow their awakening.
00:40:34 And after ten minutes, the dream has generally completely disappeared.
00:40:37 When you blush, the wall of your stomach turns red, too.
00:40:41 This happens because your blood circulates more when you are embarrassed,
00:40:44 your body preparing for something stressful to happen.
00:40:47 Your face and the wall of your stomach get more of it, which makes them red.
00:40:52 In addition, humans are the only animals that can blush.
00:40:55 At least, the only ones who have it so obvious.
00:40:57 During a lifetime, a human will grow on average 950 km of hair.
00:41:02 If they never shaved, a man would have a beard 9 meters long.
00:41:06 Hair grows a little faster in hot climates
00:41:08 because heat stimulates faster circulation in our body.
00:41:11 Everything you can know about yourself is written in one of your hair.
00:41:16 From a single hair, a scientist could say what you've eaten all your life
00:41:20 and in what kind of environment you lived.
00:41:22 On average, a human eats 45,000 kg of food during his life.
00:41:26 This represents about 10 big hippos.
00:41:29 The lips are one of the most sensitive parts of the human body.
00:41:33 They have a multitude of nerve endings, more than your fingers.
00:41:37 In addition, the skin of the lips is very thin.
00:41:39 You can see the blood vessels inside.
00:41:41 That's why your lips are red or pink, unlike the rest of your body.
00:41:45 The lips are also very sensitive to damage caused by the sun.
00:41:49 So don't forget to apply sunscreen.
00:41:51 It will protect them over time.
00:41:53 In addition to your fingerprints, your irises and your tongue,
00:41:56 your labial prints are also unique.
00:41:59 The total surface of your lungs is about the same as that of a tennis court.
00:42:03 The skin and the tendons are real balls.
00:42:05 A skin can reach a speed of 80 km/h.
00:42:08 A tendon is even faster, almost 160 km/h.
00:42:12 Unless you use your fingers, it is impossible to tend to open eyes.
00:42:17 Scientists don't really know why.
00:42:20 Some say it's just a reflex, by definition uncontrollable.
00:42:23 Others think it's to protect your eyes from what's projected.
00:42:27 All humans literally shine.
00:42:30 This light comes from the heat of your body.
00:42:32 It is in fact a thousand times less intense than what you are able to perceive.
00:42:36 But still, it's pretty awesome.
00:42:38 The biggest USB key in the world is your brain.
00:42:40 Well, anyone's brain.
00:42:42 The neurons it contains combine with each other
00:42:44 so that your storage capacity is about 1 million giga-octets.
00:42:48 That's enough to contain 3 million hours of film,
00:42:51 like a movie night that would last 300 years.
00:42:54 Pass me the popcorn.
00:42:56 You start to get thirsty when you lose about 1% of your body weight.
00:43:00 If you lose 5%, you can even feel like you're going to faint.
00:43:04 Fingers don't have their own muscles.
00:43:06 It's the muscles located in the palm and the forearm that make them move.
00:43:10 The word "muscle" actually comes from the old Latin word that means "mouse".
00:43:14 The Romans saw their biceps like that.
00:43:16 On average, in their lifetime, a person walks about 180,000 km.
00:43:20 That's four times the distance around our planet
00:43:22 or half the distance between the Earth and the Moon.
00:43:25 So don't forget to wear comfortable shoes.
00:43:28 Your brain will grow by about 2% if you venture into space.
00:43:33 Under normal gravity, we think that the liquid in the brain
00:43:36 moves naturally downwards
00:43:38 when we stand up.
00:43:40 And it's proven that the absence of gravity prevents this.
00:43:43 Which explains why the liquid would accumulate in your brain and in your skull.
00:43:47 And no, that's not where the expression "having a big head" comes from.
00:43:51 A bouquet of flowers may have a sweet scent for you,
00:43:54 but people with cacophony perceive things differently.
00:43:58 For them, all the smells in the world are unpleasant.
00:44:01 Yes, they think it stinks.
00:44:03 And by the way, among all our senses, the smell is the highest.
00:44:07 We still remember 65% of the smells after a year,
00:44:11 but only 50% of what we've seen over the last three weeks.
00:44:15 We also have a newborn every 28 days,
00:44:18 because these cells are renewed every four weeks.
00:44:21 We don't smell when we sleep.
00:44:23 Well, unless, of course, we haven't washed for a while.
00:44:27 Your smell becomes smelly when you sleep.
00:44:29 That's why it's almost impossible to notice a gas leak at night.
00:44:33 During our sleep, there are only noises that can save us,
00:44:37 because our "yes" continues to work.
00:44:39 Almost half of your taste buds will have disappeared when you're 60.
00:44:44 You may finally start eating broccoli.
00:44:47 Your smell also loses its acuity with age.
00:44:50 As for taste, again, we rely mainly on our smell,
00:44:54 because it helps us perceive up to 95% of flavors.
00:44:58 Without the smell, it would be difficult to distinguish an apple from a turnip.
00:45:02 When you cough, you expel air at about 100 km/h.
00:45:06 Be careful of the speed limit!
00:45:09 The "ok" is a two-step process.
00:45:12 First, you inhale a lot of air due to a muscle spasm,
00:45:15 and then "blanc".
00:45:17 Your respiratory tracts close, the air is blocked,
00:45:20 and the noise we all know is heard.
00:45:22 We need our ears not only to hear, but also for our balance.
00:45:27 Our vestibular system is located in the inner ear.
00:45:30 The channels contain liquid and tiny sensors that help you maintain balance.
00:45:36 In fact, ears have bones, and they are the only ones that never grow.
00:45:41 It is thanks to them that we hear, because they transmit sound vibrations.
00:45:45 Doctors call this the ossicular chain.
00:45:48 It consists of the malleus, the lincus and the stapes,
00:45:51 also known as the hammer, ankle and calf.
00:45:55 And they are an integral part of the middle ear.
00:45:58 Our ears continue to grow throughout our life.
00:46:01 They sweat too, and the cerebrum is actually the sweat they produce.
00:46:06 In fact, our nose never stops growing,
00:46:09 maybe because of all these lies.
00:46:12 The heart is the only muscle that never gets tired.
00:46:15 The aorta is massive, its diameter is almost equivalent to that of a garden watering pipe.
00:46:21 All the bones of our body are connected to each other, except the aorta,
00:46:25 which does not join the other bones.
00:46:27 This bone acts as a support for your tongue, and it is one of the most rarely broken.
00:46:32 If you have red eyes in a photo, it is the fault of the light that bounces.
00:46:36 The flash reflects on the capillaries of your retina, thus creating this effect.
00:46:41 Let's talk a little more about the eyes.
00:46:43 The most efficient camera has 200 megapixels.
00:46:46 A human eye has 576.
00:46:49 That's why sunsets are so much more beautiful in real life than in photos.
00:46:54 The roller coasters really move your organs.
00:46:57 When you feel like your stomach is falling,
00:46:59 it is because it is really being thrown inside your body.
00:47:03 The lips are much more sensitive than the fingers,
00:47:06 because they have about a million nerve endings.
00:47:09 They are 100 times more sensitive than the tip of the fingers.
00:47:12 The grooves and the sills of our lips make their imprint unique, just like our fingers,
00:47:17 and they do not change throughout our life.
00:47:20 The imprint of our tongue is also unique elsewhere.
00:47:23 All the inhabitants of the earth have a smell that is clean to them,
00:47:26 but real twins have exactly the same.
00:47:29 This must be because they have identical genes.
00:47:32 Usually, we lose about 50 to 150 hairs a day.
00:47:36 The average life span of a hair is 5 years,
00:47:39 and as soon as an old hair says goodbye to your scalp,
00:47:42 a new one begins to grow immediately.
00:47:45 In your body, you carry enough bacteria to fill a can.
00:47:49 You have about 1.5 to 2 kg of bacteria in you,
00:47:53 which is 2% of your total weight.
00:47:56 But most of them are waste from our body.
00:47:58 A human being has between 20,000 and 25,000 genes.
00:48:01 Pretty impressive, isn't it?
00:48:03 Well, cornflakes have more than us.
00:48:06 Fortunately, it is a matter of sophistication, not quantity.
00:48:10 Anyway, cornflakes 1, humans 0.
00:48:14 We are made up of many chemical elements, including iron.
00:48:17 The iron in our body is enough to produce 3 nails,
00:48:21 each 2.5 cm long.
00:48:24 The carbon we have could be used to make 900 pencils.
00:48:28 We use our feathers to make pens.
00:48:30 Oh no, these are the birds. What a distraction I am making!
00:48:34 Our liver has the superpower to regenerate if it lacks a piece.
00:48:38 It can grow back and reach the size necessary for your body.
00:48:42 Fat helps our body to assimilate vitamins.
00:48:45 Vitamins A, D, K and E can only be properly absorbed
00:48:50 if they are dissolved in fat.
00:48:52 Our body has enough fat to produce 7 soap bars.
00:48:56 But it's not like making soap at home.
00:48:58 When we are awake, our brain can produce enough energy
00:49:02 to light an electric bulb.
00:49:04 It has a power of 10 watts.
00:49:06 Eureka!
00:49:07 Our navels contain an entire animal encyclopedia,
00:49:10 with a range of about 70 different bacteria.
00:49:13 Some of them can also be found in the ground in Japan
00:49:17 and even in the shoulder glacial shell.
00:49:19 Our bodies shine, but we can't see it with the naked eye,
00:49:22 because the light we emit is a thousand times less intense
00:49:25 than the minimum level we can perceive.
00:49:28 And by the way, the carmin used in cheek lights and lipsticks
00:49:32 is a red glue made of ground beet.
00:49:35 Burrk!
00:49:36 Our saliva helps us perceive the taste of food.
00:49:39 Our taste buds only start working when they are dissolved.
00:49:43 A silk has a lifespan of only 150 days.
00:49:47 The longest silk in the world is about 10 cm long.
00:49:51 They are also the refuge of tiny aquariums.
00:49:54 We blink about 4,200,000 times a year,
00:49:58 at least once every 8 seconds.
00:50:00 It would be cool if we were given a cent every time.
00:50:03 We would earn more than 100 euros a day.
00:50:06 It may seem crazy, but our bones are stronger
00:50:09 than many building materials.
00:50:11 16 cm3 of human bones can support about 8,600 kg,
00:50:15 which is four times more resistant than concrete.
00:50:18 The only thing that makes our blood type different is sugar.
00:50:22 Groups A, B and AB contain sugars,
00:50:25 while group O does not,
00:50:28 and these donors are universal.
00:50:30 The lack of sugar does not make the blood of group O less sweet.
00:50:34 In fact, it attracts more mosquitoes than other blood types.
00:50:38 People have only 8 blood types,
00:50:40 while cows have 800 and maybe even more.
00:50:43 Positive and negative mucous, for example.
00:50:47 The nails of our fingers grow much faster than those of our toes.
00:50:51 The latter grow almost four times slower
00:50:54 because they wear less than the nails of our hands.
00:50:57 Even if we often hit them,
00:50:59 the blue ones that form there do not usually last long.
00:51:02 It does not help you to catch small things
00:51:04 and to take off stickers.
00:51:06 If you did not have this rigid structure against which to press,
00:51:09 you would not be able to judge the firmness
00:51:11 with which you have to hold objects.
00:51:13 Very few people can really digest milk.
00:51:16 The thing is that there is a special enzyme,
00:51:19 let's call it a little assistant,
00:51:21 which breaks down the sugars contained in milk.
00:51:24 As we grow up, we lose this enzyme.
00:51:26 This sugar is called lactose,
00:51:29 and adults who cannot digest it are called lactose intolerant.
00:51:33 In fact, 68% of the world's population cannot digest milk.
00:51:38 When you sleep, your whole body does not rest.
00:51:41 In reality, your brain sometimes has to work even harder.
00:51:45 It has to process tons of information,
00:51:47 and typing reports usually takes a lot of time.
00:51:50 Humans cannot do several things at once.
00:51:53 We need time to go from one task to another,
00:51:56 and if we try to tackle several things at once,
00:51:59 we will not be very productive.
00:52:01 Try this.
00:52:02 Lift your right foot and turn it clockwise.
00:52:06 Now try to write the number 6 with your big toe in the air.
00:52:10 Then check the direction in which your foot is moving.
00:52:13 It moves in the opposite direction,
00:52:15 because to write the number 6,
00:52:17 you have to move in the opposite direction of the hands of a watch.
00:52:20 A new habit takes a long time to set up.
00:52:24 It is not 100% true that 18 or 21 days is enough,
00:52:28 as many people think.
00:52:30 Acquiring a new habit can take up to 254 days,
00:52:34 but on average it takes about 66 days for something to become automatic.
00:52:40 Here are some facts that you may find difficult to digest.
00:52:45 Your stomach has an incredible capacity,
00:52:48 being able to contain up to 2 liters of liquid.
00:52:51 It is the equivalent of a large bottle of Coca-Cola.
00:52:54 It is quite difficult to estimate the amount of solid food you can ingest,
00:52:58 because it is crumbled by your teeth before reaching your stomach.
00:53:02 There is certainly not enough room for a turkey,
00:53:05 but a good-sized chicken could probably hold it.
00:53:08 If you were asked where your stomach was,
00:53:11 you would probably show your belly.
00:53:13 Sorry, but that's not the case.
00:53:15 It is actually here, hidden between your ribs.
00:53:18 Scientists think that appendix will eventually disappear.
00:53:22 Nobody really knows why we need it,
00:53:25 but some researchers say it could have existed to help our ancestors digest tree bark.
00:53:30 As it is no longer part of our daily diet,
00:53:33 the appendix is no longer necessary and can disappear from our body without any consequences.
00:53:38 The appendix is not the only obsolete part of our body.
00:53:42 Wisdom teeth are not that useful either.
00:53:45 Of course, they were when our ancestors lost some of their teeth,
00:53:48 but the only thing they help us lose now is the money we spend on their extraction.
00:53:54 Almost all of our body is covered in hair, even if we don't notice it.
00:53:59 It even grows in the navel.
00:54:01 Their function seems to be to trap the plushies in their clothes.
00:54:04 Look closely. You see?
00:54:07 Your liver acts as your personal bodyguard,
00:54:10 protecting you from toxins and many other things you shouldn't have in your body.
00:54:15 It is almost indestructible and can regenerate at any time.
00:54:20 Only 43% of your body really belongs to you.
00:54:23 More than 50% of the cells in your body belong to your tiny creatures,
00:54:27 which live mainly in your intestine.
00:54:30 Yet, even if your own cells are less numerous than those of microbial cells,
00:54:34 you have an average of 100 billion.
00:54:37 You see? You're not that lonely after all.
00:54:40 Keeping this in mind, your own genes represent less than half of what you really are.
00:54:47 If you take all the microbes that live in your body and count their genes,
00:54:51 you will find between 2 and 20 million.
00:54:54 If you sleep, it doesn't mean that your whole body is sleeping.
00:54:58 In fact, your brain sometimes has to work even harder when you sleep.
00:55:02 It needs to process tons of information, and reports usually take a long time.
00:55:07 Your nose does rest while you sleep.
00:55:10 Surprisingly, your odour is almost inactive at night.
00:55:14 You wouldn't even be embarrassed if there was a really bad smell in your room.
00:55:18 Odour is one of the most underrated senses.
00:55:21 You wouldn't even be able to enjoy eating without it.
00:55:24 About 80% of the taste of any food is felt thanks to your nose
00:55:29 and its ability to recognize odours.
00:55:32 If you pinch your nose while you eat, you will hardly taste anything.
00:55:37 If you don't have odour, you will recognize most foods by their texture,
00:55:41 so an onion might taste like an apple.
00:55:44 Try it and leave us a comment with your impressions.
00:55:48 Scientists thought we could distinguish about 10,000 odours, but they were wrong.
00:55:53 Recent research has shown that humans are actually able to distinguish more than 1 billion odours.
00:55:59 We remember as much as anything else, and odours can even evoke distant memories.
00:56:05 Your nose not only helps you breathe and sense odours,
00:56:09 it filters air for the throats and the sensitive lungs.
00:56:12 If we inhale dry air, the nose moisturizes it and cools it or warms it if necessary.
00:56:18 In addition, the nose cleanses the air of all impurities.
00:56:21 When you get older, your brain shrinks little by little.
00:56:25 At 75, it is much smaller than at 30, and it starts shrinking at 40.
00:56:30 This happens to everyone and does not affect your mental abilities.
00:56:34 Our brain can store only 7 octaves of memory in the short term.
00:56:39 Don't even try to compare your brain with the capacity of a cell phone,
00:56:43 or even the one you had in 2005.
00:56:46 That's why you have such a hard time learning a phone number by heart.
00:56:51 Our short-term memory works like a blackboard.
00:56:54 You can get information, but sooner or later, you will miss the space.
00:56:59 To know the capacity of your living memory, do this test.
00:57:03 Ask a friend to write a list of 10 words and read it to you.
00:57:07 Most people remember 7 words or less in the list.
00:57:11 RAM, or living memory, is an essential thing that we need to do almost all daily activities,
00:57:18 including basic conversations, browsing the Internet, and even petting your dog.
00:57:24 Our strongest and most emotional memories are often wrong.
00:57:28 Central memory gives us the confidence to believe that we remember everything,
00:57:32 even if most of the details are invented in our head.
00:57:36 Not only does your brain age, but you also age spectacularly.
00:57:41 Your bones become more fragile, and your spine is compressed.
00:57:45 The opposite happens when you rest at night, because your bones relax.
00:57:50 So you wake up a little bigger in the morning than in the evening.
00:57:54 In mammals, only humans can walk on two legs all their lives.
00:57:58 You might think that kangaroos or gorillas move in the same way,
00:58:02 but kangaroos use their tails as third legs, and gorillas use their long arms to keep their balance.
00:58:09 Your bones also participate in metabolism.
00:58:12 As they are mainly made of calcium, when there is not enough of this element in the blood,
00:58:17 the bones begin to reject it in the blood, which balances the body.
00:58:21 The same reaction also works in the opposite direction.
00:58:24 When there is too much calcium in your blood, it is sent to the bones to be stored there later.
00:58:30 The only bone in your body that has the humorous blood is the inside of your arm.
00:58:35 That's why the bone that is there is called the humerus.
00:58:38 No, that's totally wrong. Let's move on to the following facts.
00:58:42 The only bones that never grow up are in our ears.
00:58:45 We can hear thanks to these little bones, because they have adapted to transmit sound vibrations.
00:58:51 Doctors call them the ossicular chain.
00:58:54 One of these auditory bones, the calf, is the smallest bone in your whole body.
00:58:59 It is not larger than a grain of rice.
00:59:01 Our size, the shape of our body and the color of our skin depend a lot on where our ancestors lived,
00:59:08 but we can adapt to new conditions even during our own life.
00:59:12 For example, if you move from the plain to the mountains,
00:59:16 you will end up developing more red blood cells to compensate for the lack of oxygen.
00:59:20 And of course, if you go from a colder climate to a warmer and more sunny climate,
00:59:25 your skin will become darker to adapt.
00:59:28 Our lifespan is programmed in our cells.
00:59:31 They renew and divide constantly, but they are a kind of internal clock that stops at some point.
00:59:37 Some cells also stop reproducing earlier than others.
00:59:41 On average, cells stop dividing when we reach the age of 100.
00:59:46 This means that if we found a way to deceive our cells to stop the mutiny,
00:59:50 we could potentially live forever.
00:59:54 Body fat is not just an aesthetic nuisance.
00:59:57 It acts as an insulating material, energy reserve and shock absorber.
01:00:02 It is your body that sends the most fat into the region of your waist,
01:00:06 because that's where your internal organs are.
01:00:08 If something happens, this layer of fat could protect your vital organs from irreparable damage.
01:00:14 Be careful, your skull is not made of one bone.
01:00:17 It is actually made up of 28 different bones,
01:00:20 many of which have merged to protect your brain.
01:00:23 The jawbone or lower jaw is the only bone in the skull that is not attached to the bone around it.
01:00:29 It is attached by subjunctive tissues and muscles.
01:00:32 This makes it so mobile.
01:00:34 You can move it in the direction you want.
01:00:36 You can actually chew with your jawbone.
01:00:39 Another word to say "maché".
01:00:41 The strongest muscles of your body are not located at the level of your arms or legs.
01:00:46 They are in your head.
01:00:48 The masseter is the main muscle responsible for chewing.
01:00:52 And it must be the strongest so that you can eat normally.
01:00:56 And you know those muscles that allow you to move your ears?
01:00:59 These are the temporalis, located above your temples.
01:01:02 They also help you chew your food.
01:01:05 We have two very fast muscles, which control the closure of the eyelids.
01:01:10 These are also the fastest muscles in our body.
01:01:13 Our eyes are fragile and need protection.
01:01:16 So the reflex that protects them must be as fast as lightning.
01:01:19 These muscles can close the eyelids in less than a tenth of a second.
01:01:23 People with double-jointed thumbs can bend them backwards.
01:01:28 It seems very unusual and very few people can do it.
01:01:32 Yet it's quite commonplace.
01:01:34 Even if it looks painful, it doesn't hurt at all for someone with a double-jointed thumb.
01:01:40 We only recognize blue, yellow and red-green colors.
01:01:45 Everything else is a combination of these three colors.
01:01:48 It's impossible to calculate how many of these combinations the human eye perceives.
01:01:52 Because each person has slightly different vision.
01:01:55 But we rotate around one million combinations on average.
01:01:59 Do you see the topo?
01:02:01 Every time we bathe, we use the muscles of our mouth and tongue.
01:02:06 And this contact can compress certain glands that produce saliva.
01:02:10 As a result, we can project a tiny grain of saliva without even realizing it.
01:02:15 But it can reach 30 centimeters or more.
01:02:18 I had a friend at the university who could do that at will.
01:02:21 It was impressive.
01:02:23 It turns out that saliva is actually filtered blood.
01:02:27 The blood is treated with dedicated glands and special cells absorb these properties.
01:02:32 After that, the blood becomes saliva.
01:02:35 Another subject.
01:02:36 If your brain was a USB drive, it would be a real crazy thing.
01:02:40 The capacity of our brain is somewhere between 10 and 100 teraoctets.
01:02:45 Some scientists say that the complete spectrum can reach 2.5 petaoctets.
01:02:51 It looks like a snag for a dog, doesn't it?
01:02:53 When the size of the English version of Wikipedia was calculated in 2010,
01:02:58 it only represented 5.6 teraoctets.
01:03:01 Do you realize?
01:03:03 The heat of our body can boil almost 2 liters of water in 30 minutes.
01:03:07 Even without doing anything.
01:03:09 We should try.
01:03:11 Our brain can perform up to 10 billion operations per second with only 10 watts of energy.
01:03:17 A computer capable of doing so would need about 1 gigawatt of energy.
01:03:22 This amount can power up to 300,000 houses.
01:03:25 Our memory is affected by the position of our body.
01:03:28 For example, you are much more likely to remember a situation where you greeted someone
01:03:33 if you were standing and you did a hand sign.
01:03:36 Your brain has millions of neurons.
01:03:39 They are all different and the connection speed between each one is also different.
01:03:43 That's why you can remember some information faster than others.
01:03:47 However, our nervous impulses are very slow compared to the speed of electricity.
01:03:52 Neurons can reach a speed of 432 km/h,
01:03:56 which is slower than the fastest car in the world.
01:03:59 It's still pretty fast because your brain has to react to urgent things like pain or tickling.
01:04:05 Besides, the brain itself does not feel pain.
01:04:09 It does not have its own nervous endings.
01:04:12 People with red hair represent 1% of the entire population.
01:04:17 2% are natural blondes.
01:04:19 Yes, most of the people you see with these hair colors have brown hair.
01:04:24 Black is the most common hair color in the world.
01:04:27 Hair is not only strong, but also elastic.
01:04:31 They can stretch for about 30% of their length when they are wet.
01:04:35 The average hair growth rate is 15 cm per year.
01:04:39 So, if you never cut your hair until you are, say, 80 years old,
01:04:44 your hair will have grown 1200 cm,
01:04:47 that is the height of a four-story building.
01:04:50 However, this is not really possible because the length of our hair is genetically programmed.
01:04:56 The human eye looks like a car engine.
01:04:59 Both need liquid to be well lubricated.
01:05:02 The engine needs oil and the eye needs tears.
01:05:05 To make sure the eyes work well, tears are distributed all over the eye.
01:05:10 That's why we blink more than 10,000 times a day.
01:05:13 The ocular muscle is the fastest muscle in our body.
01:05:17 We can blink five times a second, or even more.
01:05:20 We spend about 6 seconds blinking every minute.
01:05:24 During the day, we spend 30 minutes in total darkness
01:05:28 simply because we close our eyes without counting the time we sleep.
01:05:32 The only part of the human body that does not receive any blood nutrients is the eye's cornea.
01:05:37 The only thing it needs to work well are tears and the liquid that is at the front of the eyes.
01:05:43 Most scientists agree that tears, which appear as a result of emotion,
01:05:48 are a unique human characteristic.
01:05:51 No other animal is able to cry with sadness or joy.
01:05:55 The pupils shrink and expand to control the light that enters.
01:06:00 If there is a lot of light, they shrink the passage so as not to harm the vision.
01:06:05 In the dark, the pupils expand to capture as much light as possible.
01:06:10 Now let's get back to our mouths.
01:06:13 The tongue has a lot of muscles, and some of them can only be used when you learn a new language.
01:06:19 A human bite is almost always infected, because of all the bacteria that live in our mouth.
01:06:25 In this sense, we are quite close to hyenas.
01:06:28 Your bones are designed to be used on a daily basis,
01:06:31 and some of them can absorb your body weight two or even three times.
01:06:36 It's impressive, but your teeth are even stronger.
01:06:39 When you bite something, your teeth can exert an incredible pressure, up to 90 kg.
01:06:45 By the way, the enamel is considered to be part of your skeletal system.
01:06:50 Our body is made up of about 60% water, and we even find some in the bones.
01:06:55 About 25% of the bone mass is made up of water.
01:06:59 The chloride acid present in our stomach,
01:07:02 the most important defender of our immune system,
01:07:05 helps us get rid of dangerous food toxins,
01:07:08 viruses and bacteria that accompany the food we eat.
01:07:12 The stomach itself can be digested by this acid, but the mucous membrane protects it.
01:07:17 Even if you brush your teeth twice a day and never forget to bathe,
01:07:21 your mouth remains one of the dirtiest parts of the human body.
01:07:24 Buuuurk!
01:07:26 Millions of bacteria live inside.
01:07:29 The good news is that most of these bacteria are good for the body,
01:07:33 and protect it from bad bacteria and viruses.
01:07:36 Humans and giraffes have a similar cost.
01:07:39 One person has the same number of cervical vertebrae as a giraffe.
01:07:43 The difference, however, lies in length.
01:07:46 The giraffe's vertebrae are 25 cm long.
01:07:49 Our spine can withstand a pressure of up to 450 kg.
01:07:55 It would resist an adult zebra.
01:07:58 But please, don't try to do it at home.
01:08:01 And there are no zebras anyway.
01:08:03 When you lie on your back and you raise your knees,
01:08:06 the pressure exerted on the spine is about 11 kg.
01:08:11 It's not a zebra, but rather a good-sized cat.
01:08:15 Our spine is also very flexible.
01:08:18 If we could bend it, it could form two-thirds of a full circle.
01:08:22 We are like snakes then.
01:08:24 In the morning, you are taller than in the evening.
01:08:27 During your sleep, you are no longer affected by the force of gravity,
01:08:30 and your spine stretches, which makes you gain up to 1.26 cm in height.
01:08:35 Too bad you're getting smaller every day.
01:08:38 The mountaineurs move your organs.
01:08:41 So when you feel like your stomach is falling,
01:08:44 it's because it's turning in your body.
01:08:48 You think your fingerprints are the only thing unique in your body.
01:08:52 Well, that's not the case.
01:08:54 The fingerprints of your tongue and your smell are also unique.
01:08:57 If someone sniffs you, it's enough reason to be wary.
01:09:01 If all your blood vessels were stretched in one line, it would hurt.
01:09:05 But you would go around the Earth more than twice.
01:09:08 An impressive feat that you won't see,
01:09:11 because you can't live without your blood vessels.
01:09:15 You think you're resting while you sleep,
01:09:18 but your brain never stops.
01:09:20 It's more active at night than during the day,
01:09:23 and processes all the information you've collected.
01:09:26 So show some respect for it.
01:09:28 The liver is the most active organ in the human body.
01:09:31 It has more than 500 functions,
01:09:33 and none of them are yet clear to scientists.
01:09:36 Have you ever wondered why you feel so sleepy after lunch?
01:09:40 Well, it's because your circadian rhythm,
01:09:42 which runs at a cycle of 24 hours,
01:09:44 makes you want to take a nap after 7 hours of sleep.
01:09:47 And food only strengthens this effect.
01:09:50 It's that simple.
01:09:51 Teeth and headache are linked by the trigeminal nerves.
01:09:55 They go through the jaw to the head,
01:09:57 so that when you feel a toothache,
01:09:59 it usually goes in pairs with the one in the head.
01:10:02 You lose calories no matter what you do, even nothing.
01:10:05 A good 8-hour sleep, for example,
01:10:07 allows you to lose up to 800 calories.
01:10:10 And yes, you spend energy even while eating.
01:10:13 Like all mammals,
01:10:15 we have a reflex that slows down or even stops
01:10:18 certain bodily functions to prevent us from drowning.
01:10:21 This also affects the heart rate.
01:10:24 A person can stay without food for more than 20 days.
01:10:28 However, if you don't sleep for 10 days,
01:10:31 your body will simply stop working.
01:10:34 Speaking of sleep,
01:10:35 an average person forgets 90% of their dreams.
01:10:38 And that may be a good thing.
01:10:40 Otherwise, imagine how crazy the world would be.
01:10:43 The color of your dreams is influenced by the television
01:10:46 you watched when you were a child.
01:10:48 If you are part of the older generation
01:10:50 who watched television in black and white,
01:10:53 your dreams will be mostly monochrome.
01:10:55 If you are used to colored television,
01:10:57 your dreams will also be multicolored.
01:11:00 Of the 10,000 people on Earth,
01:11:02 one person has his organs in the mirror,
01:11:04 that is, inverted compared to their usual and normal position.
01:11:08 In other words, the liver would be bigger on the left side
01:11:11 and the right kidney would be a little higher than the left.
01:11:14 Speaking of kidneys,
01:11:15 the left is a little higher than the right.
01:11:18 It's because the liver is bigger on the right side of your body.
01:11:21 People with clear, open blue eyes
01:11:24 tolerate pain better than those with dark eyes.
01:11:27 Scientists think this could be due to melanin,
01:11:30 which affects the color of the eyes.
01:11:32 The length of your foot is similar to that of your forearm.
01:11:35 If you don't believe me, do the test.
01:11:38 I'll wait for you here.
01:11:39 No!
01:11:40 Even twins don't have the same language.
01:11:44 Language is made up of a set of mobile and powerful muscles
01:11:47 that never get tired.
01:11:49 It contains between 5,000 and 10,000 taste buds.
01:11:52 These little white and pink spots on your tongue
01:11:55 are not taste buds,
01:11:57 but each of them has several inside its superficial tissue.
01:12:01 Evolution gave us taste buds
01:12:04 so that we could stay alive.
01:12:06 For example, bitter and sour flavors
01:12:08 can indicate that you are eating rotten food or toxic plants.
01:12:12 The back of the tongue is more sensitive to bitter flavors,
01:12:15 which explains why we can spit out bad food
01:12:18 before swallowing it.
01:12:20 Salty and sweet flavors tell us
01:12:22 if the food is rich in nutrients.
01:12:24 At the age of 60,
01:12:26 most people lose half of their taste buds.
01:12:29 Your tongue is cool,
01:12:31 and these taste buds can be used for biometric authentication,
01:12:34 just like digital taste buds.
01:12:36 Each of us has a different and unique tongue,
01:12:39 so if you don't want to reveal your secret identity,
01:12:42 you can hide your tongue.
01:12:44 Funny, right?
01:12:45 Why do we have digital taste buds?
01:12:47 Scientists had many different theories on the subject,
01:12:50 but today they think that it's because digital taste buds
01:12:53 allow the skin to stretch more easily.
01:12:55 They allow us to avoid bulbs,
01:12:58 protect the skin from injuries,
01:13:00 and improve our sense of touch.
01:13:02 Humans are not the only ones with unique digital taste buds.
01:13:05 Koalas too.
01:13:07 Only about 7% of people are left-handed.
01:13:10 Left-handed people chew food on the left side of their mouths,
01:13:13 while right-handed people do it on the right side.
01:13:16 We lose about 5 kg of skin cells every year.
01:13:19 But don't worry, we replace them quickly.
01:13:21 We produce 15 seconds more cells than people living in the US.
01:13:26 Our body regenerates constantly,
01:13:28 and we replace our skin hundreds of times throughout our life.
01:13:31 Yes, the whole body regenerates, except the teeth.
01:13:34 It's the only part of the body that can't do it.
01:13:37 Our teeth are similar to that of a shark.
01:13:39 Their teeth also have a substance called dentin inside,
01:13:42 and they are as solid as ours.
01:13:44 Of course, theirs are more pointed and bigger, but still.
01:13:47 Teeth are part of the human skeleton,
01:13:49 even if they are not considered bones.
01:13:52 You spend about 38 days of your life brushing your teeth.
01:13:55 And guess what? You might brush them too much.
01:13:57 Indeed, they can become more sensitive,
01:13:59 because they use natural enamel.
01:14:02 Your left and right lungs are not the same size.
01:14:04 The right is bigger, because the left shares its space with the heart.
01:14:08 Hockeying is a symptom that almost all mammals know from time to time,
01:14:12 and not just humans.
01:14:14 The record was set by a man named Charles Osborne.
01:14:17 He couldn't stop hockeying for 68 years.
01:14:20 It seems like no one told him about the thing that consists of eating sugar.
01:14:24 There is only one part of your body that doesn't receive a regular blood supply,
01:14:28 and that's your corneas.
01:14:30 They receive oxygen directly from the air.
01:14:32 Our eyes can differentiate 10 million different colors.
01:14:35 The muscles that help our eyes to focus on something
01:14:38 make about 100,000 movements a day.
01:14:40 If you wanted your legs to do the same work,
01:14:43 you would have to walk a long distance, at least 80 km.
01:14:47 We can't all see infrared light or ultraviolet rays.
01:14:50 Only 1% of us can.
01:14:53 And if you can see one of those rays,
01:14:55 it doesn't necessarily mean you can see the other.
01:14:57 Research shows that all people with blue eyes in the world
01:15:00 could be related or at least share a very distant ancestor.
01:15:04 Scientists have examined individuals with blue eyes
01:15:06 from Turkey, India, Jordan and Scandinavia.
01:15:10 They all had the same genetic sequence of the color of their eyes.
01:15:13 They think this characteristic comes from a person with blue eyes
01:15:16 whose genes mutated about 10,000 years ago.
01:15:19 Before that, the eyes were all just different shades of brown.
01:15:22 People with blue eyes are generally a little more sensitive to pain
01:15:26 than other individuals.
01:15:28 We blink about 20 times an eye in a minute,
01:15:30 which means we do it more than 10 million times a year.
01:15:34 The fact that we look like sharks also affects our eyes.
01:15:37 If a part of your eye is damaged,
01:15:39 you can replace it with a shark's.
01:15:41 It's convenient, isn't it?
01:15:43 You can't blink with your eyes open.
01:15:45 Try it!
01:15:46 It's very difficult to ignore your natural reflexes.
01:15:48 Eels also have their own life,
01:15:50 since only one eel lives about 150 days before it dies.
01:15:54 We all have goosebumps when we hear good news,
01:15:57 our favorite song,
01:15:58 or when it's ridiculously cold in the freezing rain.
01:16:01 It's a reflex that comes from our ancestors.
01:16:03 It happens when we release adrenaline.
01:16:06 It makes our hair stand on end
01:16:08 and helps us look more imposing.
01:16:10 Scary, isn't it?
01:16:12 The human brain has 100 billion neurons
01:16:15 and a memory capacity of more than 4 teraoctets,
01:16:18 which is huge.
01:16:19 Your brain uses more than a quarter of the oxygen your lungs absorb,
01:16:23 and it's mainly made up of water,
01:16:25 more than 75%.
01:16:27 It's still well hydrated.
01:16:29 It's not true that humans only use 10% of their brain.
01:16:32 We use much more than that,
01:16:34 even during our sleep.
01:16:36 Most of our brain is constantly active,
01:16:39 but we don't ask for all parts at the same time.
01:16:41 Of all species, humans are the only ones that can blush.
01:16:44 This phenomenon is due to an adrenaline rush.
01:16:47 When you feel your face turn red,
01:16:49 know that your stomach is too.
01:16:50 It's weird.
01:16:51 When you crack your joints,
01:16:54 the sound you hear is that of tiny gas bubbles that are released.
01:16:58 There are gas pockets trapped between your joints,
01:17:00 so when you stretch them, they make a dry noise.
01:17:03 Oh, how pleasant!
01:17:05 We use 43 muscles when we frown,
01:17:09 but only 17 when we smile,
01:17:11 although scientists still disagree on this point.
01:17:14 Anyway, smile!
01:17:16 An average person consumes about 33 tons of food in their lifetime.
01:17:20 That's the equivalent of 6 elephants!
01:17:22 We breathe about 11,000 liters of air per day,
01:17:25 but we can't swallow and breathe at the same time.
01:17:28 Most people need about 7 minutes to fall asleep,
01:17:31 and we're about the only living beings to sleep on our backs.
01:17:34 Randy Gardner decided to try the longest sleepless period record.
01:17:38 In 1964, he stayed awake for 11 days,
01:17:42 or 264 hours.
01:17:44 I guess he had noisy neighbors.
01:17:46 Of all animals, humans are the only ones with a chin.
01:17:49 When you're thirsty,
01:17:51 that means that the water you drink is equal to 1% of your total body weight.
01:17:56 If it exceeds 5%, you can even faint.
01:17:59 During your lifetime, your body goes from 300 bones to 206.
01:18:03 More than half of all your bones are in your feet, ankles, hands and wrists.
01:18:07 The largest human bone is the thigh bone,
01:18:10 and the smallest is called the calf bone.
01:18:12 It's inside your belly button.
01:18:14 Your nose can recognize a trillion different smells
01:18:17 and remember 50,000 of them.
01:18:19 Besides, women smell better than men,
01:18:22 and the sense of smell is 10,000 times more developed than the sense of taste.
01:18:26 The surface of our lungs is almost equal to that of a tennis court.
01:18:30 So, what is this sensation you feel when you cross a ridge on a roller coaster
01:18:35 and your stomach goes up your throat?
01:18:37 Well, the seat belt holds your body in place,
01:18:41 but your stomach, your intestines and your small internal organs,
01:18:44 they benefit from a little freedom.
01:18:46 It doesn't hurt you, but your nerves can't understand what's going on.
01:18:50 They really think your stomach is blowing into your throat.
01:18:53 We're all taller in the morning,
01:18:55 because during the day, the cartilage between our bones compresses.
01:18:59 This makes us lose about one nail at the end of each day.
01:19:02 The nose and ears are parts of the body that never stop growing.
01:19:06 It's mostly thanks to gravity.
01:19:08 The veins and arteries inside your body are long enough to go around the world twice.
01:19:13 Blood represents about 8% of your body weight.
01:19:16 When you listen to music, your heartbeat syncs with the general atmosphere of the song.
01:19:21 So, choose wisely.
01:19:23 Your skin is the largest organ in your body.
01:19:25 It accounts for about 15% of your total weight.
01:19:28 Know that you can burn more calories by sleeping than by watching TV.
01:19:32 Hmm, what if you slept while the TV was still on?
01:19:35 You can't remember a memory in its context.
01:19:39 When you try to remember a detail,
01:19:41 like the color of the T-shirt your friend wore the other day,
01:19:44 you also remember other details.
01:19:46 For example, the place where you saw it and the things you talked about.
01:19:50 The hippocampus is the part of your brain that stores memories.
01:19:53 It's used to group them together, including multiple little details.
01:19:57 The taste buds last on average 10 days.
01:20:00 They're sensory cell clots in your tongue.
01:20:03 The closest taste buds to the surface are more ephemeral.
01:20:06 That's why you don't have to wait too long to be able to taste again after your tongue has been burned.
01:20:12 A theory states that déjà vu is a sort of shift in brain treatment.
01:20:17 Scientists think it can happen when your brain transfers information from one side to the other
01:20:23 and there's a delay of a fraction of a second in this process.
01:20:26 That means your brain receives the same information twice and treats it like an event that has already happened.
01:20:32 Only 30% of people can dilate their nostrils,
01:20:35 and a third can bend their thumb backwards.
01:20:38 Some people can produce a rustling sound in their head.
01:20:42 All they need to do is stretch their ears or jaws.
01:20:45 There's a little muscle in the ear that dampens loud sounds, like when you chew.
01:20:50 But some people can flinch this muscle, and it creates an audible grunting.
01:20:55 The tip of your fingers is sensitive, but hundreds of times less than your lips.
01:20:59 You inhale many different types of debris, including 700,000 of your own cutaneous squam,
01:21:04 and that's only in one day.
01:21:06 A hypnic shake is a soft jump you can feel while you're asleep.
01:21:11 It's a sudden muscle movement that occurs during sleep, not REM.
01:21:16 It can create an illusion of falling.
01:21:19 One theory is that when you fall asleep, your brain perceives the relaxation of your muscles
01:21:24 as a sign that you have problems and that you're falling.
01:21:27 It sends signals to the muscles to protect you by contracting.
01:21:31 Synesthesia is a special and rare ability that consists of feeling the taste of music
01:21:37 or hearing the colors.
01:21:39 Only one in 2,000 people have it.
01:21:42 For some people, coriander tastes like soap,
01:21:46 because the plant contains a chemical compound used to make it.
01:21:51 But only 4 to 14% of the world's population has special genes that can detect it.
01:21:57 18% of people can move their two ears at the same time,
01:22:01 while 22% can move one ear at a time.
01:22:05 People who do it use old, weak muscles that we inherited from our ancestors
01:22:09 that we have in common with cats.
01:22:11 Hematomas change color over time.
01:22:14 A blue appears because there is a bleeding under the skin.
01:22:17 Tiny blood vessels are crushed and part of the blood is trapped in this place.
01:22:22 At first, a blue is red because this blood is rich in oxygen,
01:22:26 but then it turns purple, green, yellow or even gray when the oxygen level decreases.
01:22:31 Sweat has no odor in itself.
01:22:33 The unpleasant odor is caused by the bacteria present on your skin.
01:22:38 When sweat comes out of your pores, the bacteria decompose it into acid.
01:22:43 What most deodorants do is get rid of the bacteria on your skin.
01:22:47 People used to dream a lot more in black and white than they do today.
01:22:51 It's because they watched TV in black and white.
01:22:53 Blue cheese can influence your dreams and make them come true.
01:22:57 As for the eggshells, they could be used to grow new human bones.
01:23:02 Chicken eggshells contain calcium carbonate,
01:23:05 an element also contained in our bones.
01:23:08 The food in the plane will probably taste different from the same food on the ground.
01:23:13 It's because you lose up to 30% of the sensitivity of your taste buds
01:23:17 because of the dryness and pressure in the cabin.
01:23:21 This is particularly true for salty and sweet foods.
01:23:25 Your nostrils don't work with the same efficiency all the time.
01:23:28 When you breathe, a single nostril does most of the work, and it's ready every two hours.
01:23:35 You can't taste food without saliva.
01:23:37 Your taste buds have chemoreceptors that recognize different flavors,
01:23:42 but they need a liquid for these flavors to bind to their molecules.
01:23:46 So you can't taste things that saliva doesn't dissolve.
01:23:50 Your brain can't really feel pain.
01:23:52 It does have a pain center, but it doesn't have a pain receptor.
01:23:56 When your head hurts, you can feel it because of nerves,
01:23:59 tissues and blood vessels around your brain.
01:24:02 A single human hair can support a weight of 100 grams,
01:24:05 or the weight of two chocolate bars.
01:24:08 Nails and toes grow almost four times slower than nails and hands,
01:24:11 which are more exposed and used more frequently.
01:24:14 There must be at least a few pictures where you have red eyes.
01:24:17 When the camera flashes, your eyes aren't prepared for such a high light.
01:24:22 Your pupils are dilated, which is why the light is reflected on the red blood vessels of the coroids.
01:24:28 It's a layer of tissue at the back of your eye that feeds your retina.
01:24:32 Your right lung is bigger than the left one because your body needs to make room for the heart.
01:24:38 Your teeth are the only part of your body that can't heal on its own.
01:24:42 The masseter is the most powerful muscle you have in relation to its weight.
01:24:47 With the rest of the muscles in the jaw, it can close your teeth with a force of 90 kg on the molar
01:24:52 and 25 kg at the incisors.
01:24:55 Onions produce a special chemical irritant that stimulates special glands in your eyes,
01:25:00 which causes them to release tears.
01:25:03 Your nose can memorize up to 50,000 smells.
01:25:06 Your nose can memorize up to 50,000 different smells and detect more than 1,000 billion smells.
01:25:11 We all have a unique smell, except for real twins.
01:25:14 This smell is partly determined by genetics,
01:25:17 but it also depends on your diet, your hygiene and the environment.
01:25:21 Eating snow is not the best way to stay hydrated.
01:25:24 Your body needs too much energy to turn it into water.
01:25:28 Snow can give you a little hydration, but it will also lower your body temperature,
01:25:33 which is not the best scenario if you try to survive in difficult winter conditions.
01:25:38 You burn between 100 and 200 calories per hour while standing.
01:25:42 Sitting position burns 60 to 130 calories depending on your size, weight, sex and age.
01:25:48 Brain freezing is a headache caused by ice.
01:25:52 This is how your brain tells you to slow down and maybe stop eating something very cold.
01:25:58 The main goal of the eyelashes is to protect your eyes from the sand, humidity, dust and debris in the air.
01:26:05 Your eyelashes detect when something is too close to your eyes,
01:26:09 like an insect flying at you and triggering a blinking reflex.
01:26:13 Blinking your eyes also helps when you have to evacuate tiny particles or debris stuck in your eyelids.
01:26:19 These are small openings you have in your eyelids, this is where tears are created.
01:26:24 As for your eyebrows, they prevent sweat from flowing directly into your eyes.
01:26:28 Your skin in this place and the shape of your eyes also work together to direct sweat to the sides of your face.
01:26:35 We are not the fastest, strongest or tallest in the animal kingdom,
01:26:39 but we are the best at running long distances.
01:26:42 It is because we have long legs and that our body can lose excess heat by sweating.
01:26:47 A long time ago, our ancestors hunted animals by chasing them for long periods.
01:26:53 This ended up exhausting the little creatures.
01:26:56 The five basic senses are taste, touch, sight, sound and smell, but people have more sense than that.
01:27:03 Proprioception is the fact of being aware of parts of your body and their position, even if you do not see them.
01:27:09 For example, if your arm is behind your back, you know it's there.
01:27:13 If you were a pigeon, you wouldn't know it,
01:27:15 because these creatures don't know that their tentacles exist if they don't see them.
01:27:20 Thermoception is the ability to perceive temperature.
01:27:24 Equilibrioception is the sense of balance.
01:27:27 There is also nociception, which allows you to feel pain,
01:27:30 and chronoception, which is the way you can feel the time passing.
01:27:34 There is even more sense in the animal kingdom.
01:27:37 Electroreception and magnetoreception, but humans don't have them.
01:27:41 You can't see your taste buds.
01:27:44 These little bumps on the tongue are lingual gums.
01:27:47 There are four kinds of them.
01:27:48 Circumvalate, foliate, fongiform, filiform.
01:27:52 They are all covered with gustative papillae, except the last one, filiform.
01:27:56 Papillae filiform, seen through a microscope.
01:27:59 This one is responsible for the sense of touch of your tongue.
01:28:02 Your auricle is responsible for 50% of the total force you have in your hand.
01:28:06 Your liver is a very important organ that works a lot and is responsible for 500 individual functions.
01:28:12 Up to 10% of its content is composed of fat.
01:28:15 The liver can regenerate.
01:28:17 You can burn calories when you take a hot bath.
01:28:20 As much as if you were taking a 30-minute walk.
01:28:23 People usually need 7 minutes to fall asleep.
01:28:26 This time is shorter if you just ate a meal.
01:28:29 On average, your heart is as big as your fist.
01:28:32 It beats 115,000 times and pumps about 7,600 liters of blood per day.
01:28:37 About 6% of people can quickly vibrate their front and back eyeballs.
01:28:44 This doesn't mean that something is wrong with their eyes.
01:28:47 It's just a single turn that they are able to perform.
01:28:50 Your bones are designed to be very demanding on a daily basis.
01:28:54 And some of them can absorb your weight two or even three times.
01:28:57 It's impressive, but your teeth are even stronger.
01:29:00 When you bite something, the teeth can exert an incredible pressure, up to 90 kilos.
01:29:06 In fact, the enamel is considered part of your skeletal system.
01:29:10 Your stomach has a fairly incredible container.
01:29:13 Up to 2 liters of liquid, which is the equivalent of a large bottle of Coca-Cola.
01:29:17 It's quite difficult to estimate the amount of hard food you can get into your stomach.
01:29:22 Because the food is transformed by your teeth before it gets inside.
01:29:26 There's certainly not enough room for a turkey, but a good-sized chicken could probably fit in there.
01:29:31 Every time you turn your hand, the bones inside cross.
01:29:35 Hold your forearm and check.
01:29:38 Now you know where exactly your stomach is.
01:29:41 If you think it's in your stomach, you're wrong.
01:29:44 It's hidden here, between your ribs.
01:29:46 You probably already know that your body is made up of about 60% water.
01:29:50 But what's less known is that your bones are also part of it.
01:29:53 About 25% of the bone mass of humans is made up of water.
01:29:57 Scientists think the appendix is doomed to disappear.
01:30:00 Nobody really knows why we need it,
01:30:03 but some researchers say it helped our ancestors assimilate the tree bark they ate.
01:30:08 Since it's no longer part of our daily diet,
01:30:11 the appendix could disappear from our body without any consequences.
01:30:14 The human eye is somewhat similar to the motor of a car.
01:30:17 Both need different fluids to function properly.
01:30:20 An engine needs fuel, and an eye needs tears.
01:30:24 To function properly, tears need to be distributed throughout the eye.
01:30:28 That's why we blink our eyes up to 20,000 times a day.
01:30:31 So we can say that the eyelid plays a bit of the same role as the windshield.
01:30:35 Almost all of our body is covered in hair, even if we don't notice it.
01:30:39 It grows even in the navel.
01:30:41 Their function is to catch the plushies.
01:30:43 The only part of the human body that doesn't receive any blood nutrients is the eye cornea.
01:30:47 Instead, it's fed by the tears and the fluid that's in front of your eyes.
01:30:52 If you never knew you had a personal bodyguard, think about it more seriously.
01:30:56 Your liver is your personal safety agent,
01:30:59 which protects you from toxins and many other things you don't want to have.
01:31:02 It's almost indestructible and can regenerate.
01:31:05 When you blush, it means your blood flow is increasing.
01:31:09 Not only does your cheeks turn red, but your stomach wall too.
01:31:13 That's because it contains a lot of blood vessels,
01:31:16 and when there's more blood than usual, it turns red.
01:31:19 Only 43% of your body really belongs to you.
01:31:22 You're made up of more than 50% of tiny, little creatures
01:31:26 that live mainly in your intestine and other parts of your body,
01:31:29 without ever leaving it.
01:31:31 Even though your own cells are less numerous than microbial cells,
01:31:34 you still have about 100 trillion.
01:31:37 Don't hesitate to count them if you don't believe it.
01:31:39 Your stomach wall is renewed every 3-4 days
01:31:42 to prevent it from eating itself.
01:31:45 The digestive acids we have can be very harmful.
01:31:49 One thing that surely rests while you sleep is your nose.
01:31:52 You won't feel anything unpleasant in your sleep.
01:31:55 The fact is that your smell is practically deactivated at night.
01:31:58 If there's a smelly smell in your room, you won't even be bothered.
01:32:02 We can accidentally digest small plastic objects,
01:32:05 glass, coins, and many more.
01:32:08 They will come out through the digestive tube in 48 hours.
01:32:11 No need to do the test, you can trust us on that.
01:32:14 Scientists used to think that we could distinguish about 10,000 smells.
01:32:19 But recent research has shown that we are actually able to distinguish more than a trillion.
01:32:24 We also remember it better than anything else.
01:32:27 And smells can even evoke distant memories.
01:32:30 We can digest tiny amounts of plastic,
01:32:33 but the human digestive system can't really stand grass.
01:32:36 Animals that brood have special teeth and several stomachs to treat leaves and raw grass,
01:32:41 while we have nothing of the sort.
01:32:43 Among mammals, only humans can walk on their two hind legs
01:32:48 and keep this posture for the rest of their lives.
01:32:50 You could argue that kangaroos or gorillas move in the same way,
01:32:54 but the first use their tails as a third leg,
01:32:57 and the second use their long arms to keep their balance.
01:33:00 The stomach is the most important defender of the immune system.
01:33:03 The chloride acid in our stomach kills the dangerous food toxins,
01:33:07 viruses and bacteria that enter with the food you eat.
01:33:11 This acid can even digest the stomach itself, but the mucous protects it.
01:33:15 Body fat is not totally bad.
01:33:18 It serves as an insulating material, energy reserve, and cushion.
01:33:22 Your body sends the most fat into your waist region,
01:33:25 because that's where your internal organs are.
01:33:27 If something happens to you, this layer of fat could protect your vital organs from irreparable damage.
01:33:33 We have two really fast muscles,
01:33:36 which control the closure of the eyelids.
01:33:38 They are even the fastest muscles in our body.
01:33:41 The eyes are fragile and need to be protected.
01:33:44 That's why when the reflex is triggered,
01:33:46 these muscles close the eyes in about 100 milliseconds,
01:33:48 or a tenth of a second.
01:33:50 We only see purple, blue, green, and red.
01:33:54 Everything else is a combination of these three shades.
01:33:57 It's impossible to calculate the number of these combinations that the human eye sees,
01:34:01 because each person has slight visual differences.
01:34:04 But there are about a million combinations on average.
01:34:07 Even if you brush your teeth twice a day and never forget to wash your mouth,
01:34:11 your mouth remains one of the dirtiest parts of the human body.
01:34:14 Millions of bacteria live there.
01:34:16 The good news is that most of these bacteria are good for the body
01:34:20 and protect it from bad bacteria and viruses.
01:34:22 The second dirtiest part is your navel,
01:34:25 and that's probably because it's the first place to be ignored.
01:34:28 The fact is that we don't really use it after we're born,
01:34:31 so this neglected area accumulates all kinds of germs, sweat, and dirt.
01:34:36 The navel houses more than 2,300 bacterial species,
01:34:39 and it needs special attention.
01:34:42 You think you owe your strong hand to your intense weight training sessions?
01:34:46 Well, you should thank your little finger.
01:34:49 Well, maybe not, but the ear is the strongest finger.
01:34:52 It's responsible for 50% of the strength of your hand.
01:34:55 Yet the most used finger is the thumb.
01:34:58 It alone ensures 40% of the action of the hand.
01:35:01 It's probably the most important finger too.
01:35:04 As for your toes, they support about 40% of your weight.
01:35:08 If you've heard that humans don't really need their toes, that's wrong.
01:35:12 They're also the main support for walking.
01:35:15 Tomatoes have more genes than humans.
01:35:17 But that shouldn't worry you, because it's not the number of genes that count,
01:35:21 but the complexity of their connections.
01:35:23 Nails don't just help us open plastic packages and take off stickers.
01:35:27 If you didn't have a rigid structure to lean on,
01:35:30 you wouldn't be able to judge the firmness with which you have to hold anything.
01:35:34 The color of our hair is easily explained by genes.
01:35:37 There's not more than 2% of people in the world who have naturally red hair.
01:35:41 They're followed by blondes, about 3%,
01:35:44 and by all the shades of brown, only about 11%.
01:35:47 The vast majority of humans have black hair.
01:35:50 Hair can stop growing at a certain length.
01:35:53 Hair usually grows for 2 to 7 years,
01:35:56 and usually doesn't exceed 106 cm.
01:35:59 However, a Chinese woman broke the record for the longest hair of all time.
01:36:04 In 2004, her hair was 5.60 meters long.
01:36:08 Even better than the answer.
01:36:10 When we laugh, think, look at something, dream, move, or do any other activity with our body,
01:36:16 small electrical and chemical signals circulate between neurons along these connections.
01:36:21 Our brain is always active,
01:36:23 sometimes even more when we sleep than when we're awake.
01:36:26 And during this process, neurons produce and send more information than all the phones in the world.
01:36:32 You're sitting somewhere outside, and an insect lands on your leg.
01:36:36 Your skin has sensory neurons,
01:36:38 and they send the message to your brain at an impressive speed of 193 km/h.
01:36:43 The brain sends the message back to your leg so that it shakes the insect very quickly.
01:36:47 And the speed at which the information travels is even faster, 320 km/h.
01:36:52 Your toes grow about 4 times as fast as your fingertips.
01:36:56 This happens because we do more with our hands than with our feet,
01:37:00 and we damage our fingertips more.
01:37:03 There's a good chance that your right hand houses different types of microbes than your left hand.
01:37:08 This happens because they cover our skin from head to toe,
01:37:11 and their variety depends on the thickness of our skin, humidity, temperature, texture, and chemistry,
01:37:17 which can change when we use our right and left hands in different ways.
01:37:21 Our nails and hair are made of keratin,
01:37:24 a material that we also find in some parts of other animals' bodies,
01:37:28 such as claws, soles, horns, wool, fur, feathers, beaks, turtle shells, or even the spiky parts of porcupine.
01:37:36 Our body is made of star dust.
01:37:38 The most complex elements of our body can only come from supernovas.
01:37:43 The first stars were only gaseous amalgams that were attracted together,
01:37:47 and at some point started the combustion process.
01:37:50 This eventually led to a nuclear reaction in its center.
01:37:53 The stars that were there just after the Big Bang were more than 50 times bigger than our current sun.
01:37:58 Inside them, there was a constant process of making elements,
01:38:02 and these big stars burned their fuel faster.
01:38:05 Most of the elements of the human body were formed in these stars for billions of years.
01:38:10 And so we can say that a part of you is immortal.
01:38:13 Not bad, is it?