80+ Faits Qui Vous Feront Dire "Sérieusement, Corps ?"

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Transcript

00:00:00 We, humans, have evolved for 6 million years, but we are still not perfect.

00:00:07 It turns out that our bodies have a lot of design flaws.

00:00:10 First of all, human eyes have tiny blind spots.

00:00:14 These spots are about the size of a pinhead and are located where the optic nerve

00:00:19 crosses the surface of the retina at the back of the eye.

00:00:22 Your optic nerves connect your eyes to your brain.

00:00:25 They carry images that your brain must process.

00:00:27 This is how you can see.

00:00:29 But where these nerves leave your eye, there are missing elements called photoreceptors.

00:00:34 These receptors detect light and are the reason why you can see.

00:00:38 Without them, your eyes would not be able to send signals to your brain to describe what you are looking at.

00:00:44 But since there are no photoreceptors at this precise location, you have a small blind spot in each of your eyes.

00:00:50 If humans were perfectly designed, without this flaw, they would have eyes like those of a pine tree.

00:00:55 This may seem strange, but the eyes of these creatures are strangely similar to those of humans.

00:01:00 Only their optic nerves pass behind the retina.

00:01:03 This means that the nerves do not need to leave the eye at any given time.

00:01:07 They therefore do not have a void that causes the blind spot of human eyes.

00:01:11 What else?

00:01:12 About 65 million Americans complain of having back problems, and this is because of evolution.

00:01:18 Just like dogs, humans used to walk on all fours.

00:01:22 When people walked on their hands and knees, the curve of their spine was almost perfect,

00:01:27 and all their organs were comfortable.

00:01:30 For this reason, there was never any pressure on their backs.

00:01:33 We have evolved to start walking on two legs to save energy.

00:01:38 The search for food took more and more time,

00:01:41 but by walking on two legs, humans have saved 25% of their energy.

00:01:46 But this was accompanied by back pain,

00:01:48 because in this way, the spine had to support all the weight and make room for other organs.

00:01:55 If your spine was perfectly straight, you would not be able to walk on two legs.

00:02:00 It has therefore evolved to become curved, but this puts a lot of pressure on the bottom of your back.

00:02:05 So, to get rid of your back problems, you should start walking on all fours again.

00:02:10 Humans have too many bones in their feet.

00:02:13 We have all these bones because our Sienese ancestors needed them to hang on the branches of trees.

00:02:18 Nowadays, people no longer swing on trees,

00:02:21 but we still have all these bones, which makes us inclined to damage them.

00:02:25 And it can be extremely painful.

00:02:27 Think of the number of times you've hit your toes.

00:02:30 Ouch!

00:02:31 If we were perfectly designed, our feet would look like those of an ostrich.

00:02:35 These birds have much fewer bones,

00:02:37 and the parts that look like knees turned backwards are actually the joints of their ankles.

00:02:42 This makes ostriches less prone to injury and also helps them run fast.

00:02:47 If humans were designed this way, the Olympic Games would be much more interesting.

00:02:52 Human teeth are also far from perfect, and we spend so much money to treat them.

00:02:58 No other animal should go to the dentist like we do.

00:03:01 In addition, once our teeth are definitively damaged or they fall, we will not be able to grow new ones.

00:03:07 On the contrary, sharks can. They have an inexhaustible reserve of teeth.

00:03:12 In some species of sharks, a new series of teeth develops every two weeks.

00:03:17 Kangaroos also have much better teeth than humans.

00:03:21 If we were perfectly designed, we would probably have the same teeth as our Australian friends, mounted on springs.

00:03:27 Once their teeth are worn out, they fall and their back teeth migrate forward.

00:03:32 This is not the only problem we have with our teeth. Our mouths are way too crowded.

00:03:37 As evolution progresses, the human brain has grown spectacularly,

00:03:41 and our jaws have had to become wider and shorter to make room for them.

00:03:46 But this left almost no room for our wisdom teeth.

00:03:49 In the past, these teeth were useful for tearing food,

00:03:53 but when we learned to cook and transform food, these teeth were no longer necessary.

00:03:58 So, in summary, people should simply get rid of them completely.

00:04:02 And that may be what is happening.

00:04:05 About 25% of humans are born today without a part, or even the entirety, of their four wisdom teeth.

00:04:12 It turns out that our knees are not very practical either, even if it is the most complex joint in the body.

00:04:18 It is sandwiched between two massive levers, which is already quite risky.

00:04:23 And the knee can only move forward or backward, which does not make it a very safe construction.

00:04:29 This is why there are a whole bunch of rules in many sports,

00:04:32 like football or rugby, which prohibit hitting the knee of an opponent on the side.

00:04:37 For people to be better adapted to their new sports lifestyle,

00:04:40 the mechanism of the knee, which looks like a hinge, could be replaced by a spheroid joint.

00:04:46 It would look like the structure you have in your shoulders and hips.

00:04:50 Like cats and dogs, some humans can move their ears.

00:04:54 These lucky ones can move their ears independently,

00:04:57 thanks to special muscles called "extrinsic ear muscles".

00:05:01 But these are literally useless, except for doing something nice to impress your friends.

00:05:07 Speaking of design flaws, human vocal cords are also in the wrong place.

00:05:12 Your throat, through which you breathe, and your food tube, which is where the food goes down,

00:05:17 end up in the same space. This space extends from your nose and your mouth to your vocal cord.

00:05:23 You have a small flap in the shape of a leaf that covers the opening of your larynx, or vocal cord, when you swallow.

00:05:29 It prevents food from entering your throat. But this mechanism is not always fast enough.

00:05:35 If you talk while eating, it is incredibly easy for food to slide down

00:05:40 and accidentally enter your respiratory tract.

00:05:43 And it is better to avoid this. The larynx of the whale is designed in a much more judicious way.

00:05:49 It is located in its nostril, far from its mouth.

00:05:52 If people could move their vocal cords in their nose, they would have two separate tubes,

00:05:56 and there would be no more risk of suffocation by taking a wrong path.

00:06:00 But there would be a drawback. We could not talk.

00:06:03 However, we could communicate by singing instead, like our whale friends.

00:06:07 We could do it by producing vibrations in our nose.

00:06:11 Do you like cutlets? Some humans have a thirteenth additional pair of ribs.

00:06:15 Between 1 and 3% of the world's population have these ribs, called cervical, and they are absolutely useless.

00:06:23 Some people have only one of these ribs on the left or right side of their body,

00:06:27 and others have two cervical ribs on both sides.

00:06:30 You do not need your appendix either.

00:06:32 It can contain some useful bacteria to help you when you have stomach problems,

00:06:36 but apart from that, it is not really necessary.

00:06:39 The worst is that the appendix can easily catch fire.

00:06:42 The appendix was originally designed to help people digest the cellulose found in most green plants.

00:06:48 It was at the time when the human diet was mainly made up of plants with very little animal food.

00:06:55 So let's get rid of it.

00:06:57 Let's continue.

00:06:58 Blood is passed from your heart to all the tissues of your body through thin pipes called arteries.

00:07:04 Blood circulates in each of your arms and legs through a large artery.

00:07:08 For your arms, this artery is located at the level of the biceps,

00:07:11 and for your legs, it is located at the front of the thigh.

00:07:14 But your back also needs blood, and instead of having a large artery at the back of your body,

00:07:19 you have smaller ones that branch out and wrap around your bones and nerves.

00:07:24 It is really not very practical, and it makes people very sensitive to dysfunction.

00:07:28 This is why you often have swollen arms or legs.

00:07:31 Now, take a look at your elbow.

00:07:34 Here, a branch of the artery meets an element called the cubital nerve.

00:07:38 It is thanks to it that you can move your little finger.

00:07:41 But it is also because of it that when you hit yourself with the humerus, you have ants in your arm.

00:07:46 To solve this problem, we would need an additional large artery at the back of our body, near the shoulder blades.

00:07:53 This additional pipe would provide your blood with a more direct route.

00:07:56 This would also prevent your arms and legs from having ants when you hit them in the wrong place.

00:08:01 To finish, humans still have a coccyx, but no longer a tail.

00:08:05 For our Siamese ancestors, the tail was incredibly useful.

00:08:09 They used it to balance themselves by jumping from one branch to another.

00:08:13 Now that we live in houses on the ground, most of us no longer swing in the trees.

00:08:18 However, the coccyx breaks easily, so it is no longer a design flaw.

00:08:23 Researchers also claim that its elimination would also solve posture problems.

00:08:29 You cannot remember a memory in its context.

00:08:32 When you try to remember a detail, like the color of the t-shirt your friend wore the other day, you also remember other details.

00:08:39 For example, the place where you saw it and the things you talked about.

00:08:43 The hippocampus is the part of your brain that stores memories.

00:08:46 It is used to grouping them, including multiple small details.

00:08:50 The gustatory papillae last on average 10 days.

00:08:53 These are sensory cell clots in your tongue.

00:08:56 The papillae closest to the surface are more ephemeral.

00:08:59 This is why you do not need to wait too long to be able to taste again after the tongue has been burned.

00:09:05 A theory states that the déjà vu is a kind of offset in brain treatment.

00:09:10 Scientists think that this can happen when your brain transfers information from one side to the other

00:09:16 and that there is a delay of a fraction of a second in this process.

00:09:19 This means that your brain receives the same information twice and treats it like an event that has already occurred.

00:09:25 Only 30% of people can dilate their nostrils and a third can bend their thumb backwards.

00:09:31 Some people can produce a rustling noise in their heads.

00:09:35 All they need to do is stretch their ears or jaws.

00:09:38 There is a small muscle in the ear that dampens loud sounds, like when you chew.

00:09:43 But some people can itch this muscle, and it creates an audible grunting.

00:09:48 The tip of your fingers is sensitive, but hundreds of times less than your lips.

00:09:52 You inhale many different types of debris, including 700,000 of your own tanned squam, and that's just in one day.

00:09:59 A hypnic shake is a soft jump that you can feel while you are sleeping.

00:10:04 It is a sudden muscle movement that occurs during the sleep phase, not REM.

00:10:09 It can create an illusion of falling.

00:10:12 One of the theories is that when you fall asleep, your brain perceives the relaxation of your muscles

00:10:17 as a sign that you have problems and that you are falling.

00:10:20 It sends signals to the muscles to protect you by contracting.

00:10:24 Synesthesia is a special and rare ability that consists of feeling the taste of music or hearing the colors.

00:10:31 Only one in 2,000 people have it.

00:10:34 For some people, coriander may taste similar to soap,

00:10:38 because the plant contains a chemical compound used in the manufacture of it.

00:10:43 But only 4 to 14% of the world's population has the special genes that can detect it.

00:10:49 18% of people can move their two ears at the same time,

00:10:53 while 22% can move one ear at a time.

00:10:57 People who do it use old weak muscles that we inherited from the ancestor we have in common with cats.

00:11:03 Hematomas change color over time.

00:11:06 A blue appears because there is a bleeding under the skin.

00:11:09 Tiny blood vessels are crushed and part of the blood is trapped in this place.

00:11:14 At first, a blue is red because this blood is rich in oxygen,

00:11:19 but then it turns purple, green, yellow or even gray when the oxygen level decreases.

00:11:24 Sweat has no odor in itself.

00:11:26 The unpleasant odor is caused by the bacteria present on your skin.

00:11:30 When sweat comes out of the pores of your body, the bacteria decompose it into acid.

00:11:35 What most deodorants do is get rid of the bacteria on your skin.

00:11:40 People used to dream a lot more in black and white than they do today.

00:11:44 It's because they watched TV in black and white.

00:11:46 Blue cheese can influence your dreams and make them more alive.

00:11:50 As for the two shells, they could be used to grow new human bones.

00:11:55 Chicken eggs contain calcium carbonate, an element also contained in our bones.

00:12:01 The food in the plane will probably taste different from the same food on the ground.

00:12:06 It's because you lose up to 30% of the sensitivity of your taste buds

00:12:10 because of the dryness and pressure in the cabin.

00:12:13 This is particularly true for salty and sweet foods.

00:12:17 Your nostrils do not work with the same efficiency all the time.

00:12:21 When you breathe, a single nostril does most of the work and it is relayed every two hours.

00:12:27 You can't taste food without saliva.

00:12:30 Your taste buds have chemoreceptors that recognize different flavors,

00:12:34 but they need a liquid for these flavors to bind to their molecules.

00:12:38 So you can't taste things that saliva doesn't dissolve.

00:12:42 The brain can't really feel pain.

00:12:45 It does have a pain center, but it doesn't have a pain receptor.

00:12:49 When your head hurts, you can feel it because of nerves, tissues and blood vessels around your brain.

00:12:55 A single human hair can support a weight of 100 grams, or the weight of two chocolate bars.

00:13:00 The nails and toes grow almost four times slower than the nails and hands,

00:13:04 which are more exposed and used more frequently.

00:13:07 There must be at least a few photos where you have red eyes.

00:13:10 When the flash of the camera starts up, your eyes are not prepared for such a flood of light.

00:13:15 Your pupils remain dilated.

00:13:17 This is why the light is reflected on the red blood vessels of the coroid.

00:13:21 It is a layer of tissue at the back of your eye that nourishes your retina.

00:13:25 Your right lung is larger than the left one because your body needs to make room for the heart.

00:13:31 Your teeth are the only part of your body that can't heal on its own.

00:13:35 The masseter is the most powerful muscle you have compared to its weight.

00:13:39 With the rest of the muscles of the jaw, it can close your teeth with a force of 90 kilos on the molar

00:13:45 and 25 kilos at the incisors.

00:13:48 Onions produce a special chemical irritant that stimulates special glands in your eyes,

00:13:53 which causes them to release tears.

00:13:56 Your nose can memorize up to 50,000 smells.

00:13:59 Your nose can memorize up to 50,000 different smells and detect more than 1,000 billion smells.

00:14:04 We all have a unique smell, except for real twins.

00:14:07 This smell is partly determined by genetics,

00:14:10 but it also depends on your diet, your hygiene and the environment.

00:14:14 Eating snow is not the best way to stay hydrated.

00:14:17 Your body needs too much energy to turn it into water.

00:14:21 Snow can give you a little hydration, but it will also lower your body temperature,

00:14:26 which is not the best scenario if you try to survive in difficult winter conditions.

00:14:32 You burn between 100 and 200 calories per hour while standing.

00:14:35 The sitting position burns 60 to 130 calories depending on your size, weight, sex and age.

00:14:42 Brain freeze is a headache caused by ice.

00:14:45 This is how your brain tells you to slow down and maybe stop eating something very cold.

00:14:51 The main purpose of the incisors is to protect your eyes from the sand, humidity, dust and debris in the air.

00:14:58 Your incisors detect when something is too close to your eyes,

00:15:02 like an insect flying at you and triggers a reflex of blinking.

00:15:06 Blinking also helps you when you have to evacuate tiny particles or debris stuck in your pupils.

00:15:12 These are small openings in your pupils.

00:15:15 This is where tears are created.

00:15:17 As for your eyebrows, they prevent sweat from flowing directly into your eyes.

00:15:21 Your skin here and the shape of your bones also work together to direct the sweat to the sides of your face.

00:15:28 We are not the fastest, strongest or tallest in the animal kingdom,

00:15:32 but we are the best at running long distances.

00:15:35 It is because we have long legs that our body can lose excess heat by sweating.

00:15:40 A long time ago, our ancestors hunted animals by chasing them for long periods.

00:15:46 This ended up exhausting the little creatures.

00:15:49 The five basic senses are taste, touch, sight, sound and smell, but people have more sense than that.

00:15:56 The proprioception is the fact of being aware of the parts of your body and their position, even if you do not see them.

00:16:02 For example, if your arm is behind your back, you know it's there.

00:16:06 If you were a pioper, you wouldn't know it, because these creatures don't know that their tentacles exist if they don't see them.

00:16:13 Thermoception is the ability to perceive temperature.

00:16:17 Equilibrioception is the sense of balance.

00:16:20 There is also nociception, which allows you to feel pain,

00:16:23 and chronoception, which is the way you can feel the time passing.

00:16:27 There is even more sense in the animal kingdom.

00:16:30 Electroreception and magnetoreception, but humans don't have them.

00:16:34 You can't see your taste buds.

00:16:37 These little bumps on the tongue are lingual buds.

00:16:40 There are four kinds of them.

00:16:41 Circum, valate, folie, fongiform, filiform.

00:16:45 They are all covered with taste buds, except the last one, filiform.

00:16:49 Papillifiliform seen through a microscope.

00:16:52 It is responsible for the sense of touch of your tongue.

00:16:54 Your auricle is responsible for 50% of the total force you have in your hand.

00:16:59 Your liver is a very important organ that works a lot and is responsible for 500 individual functions.

00:17:05 Up to 10% of its content is composed of fat.

00:17:08 The liver can regenerate.

00:17:10 You can burn calories when you take a hot bath, as much as if you were taking a half-hour walk.

00:17:15 People usually need 7 minutes to fall asleep.

00:17:18 This time is shorter if you just ate a meal with a spoon.

00:17:21 On average, your heart is as big as your fist.

00:17:24 It beats 115,000 times and pumps about 7,600 liters of blood per day.

00:17:29 What do you call a person who can write with both his left and right hand?

00:17:34 Can you reach the inside of your nose with your tongue?

00:17:38 And why would you do that?

00:17:40 Find out if you have a real superpower!

00:17:43 About a third of people can lift a eyebrow, left or right.

00:17:49 It's a great way to send a signal to someone while telling a joke.

00:17:53 But the ability to lift both eyebrows separately is much rarer.

00:17:57 If you are not one of these people, it is because you cannot control and move the corresponding muscles.

00:18:03 But this skill can be developed.

00:18:05 Put yourself in front of a mirror, hold one eyebrow with your hand and lift the other from top to bottom.

00:18:10 Then do the same with the other eyebrow.

00:18:12 This will train you to move separately.

00:18:14 Can you sit on the floor and get up without the help of your hands or your knees?

00:18:19 This simple challenge is called the sitting back test.

00:18:22 Although scientists debate whether this test is reliable,

00:18:25 in order to assert anything about your health,

00:18:28 you can still use it to check if your muscles and your heart are strong enough.

00:18:32 If you are unable to get up from the floor without the support of your hands or your knees,

00:18:36 it may be time to go back to the gym.

00:18:39 Take your hand and place a ring on the hollow of your elbow, then rotate your palm.

00:18:44 If the ring does not fall, you are a rare person.

00:18:47 Some say that only 2% of people can do it, even if this figure is debatable.

00:18:52 If you manage to lick your elbow or touch your forearm with your thumb, congratulations, you are a minority.

00:18:59 But some people do not have the flexibility at the higher level.

00:19:03 This condition is called hypermobility.

00:19:05 It allows rare individuals to bend their bodies in weird positions, like a snake,

00:19:10 put their head between their feet, make a back bridge and all kinds of wide gaps.

00:19:15 But in some cases, hypermobility can also increase sensitivity,

00:19:19 because these people have a larger medullary area.

00:19:22 This area of the brain is responsible for the treatment of emotions.

00:19:25 90% of people are right-handed and only 10% are left-handed.

00:19:30 But there is also a very small percentage of people who can use both hands as well as the other,

00:19:35 including to write, draw and do any task.

00:19:39 Naturally, ambidextrous people only represent 1% of the population, that is, about 70 million people.

00:19:46 If you want to check if you are one of them, try to write the same sentence with both hands,

00:19:50 or draw a circle first with your right hand, then with your left hand, if there is no difference.

00:19:56 Congratulations!

00:19:58 In fact, these exercises are very good for balancing the hemispheres of the brain, whatever your dominant hand.

00:20:03 Writing in a mirror is another good way to wake up your neurons.

00:20:08 Leonardo da Vinci used to write his thoughts in a newspaper from right to left.

00:20:13 The real purpose of his writing in a mirror is still unknown.

00:20:16 But some people suggest that he was simply trying to avoid blurring his ink page because he was left-handed.

00:20:22 But be careful! Writing a text in a mirror is not an easy task for most people.

00:20:27 Most people depend on weather forecasts and have to adapt their outfit according to the season to avoid catching a cold.

00:20:34 But not everyone!

00:20:35 Some lucky people have learned to keep their bodies warm at all times.

00:20:39 These fearless heroes can walk in the cold wearing only a swimsuit.

00:20:44 They can stand in the snow, barefoot, and even swim in a frozen river or an ice hole.

00:20:49 In general, this gift does not come naturally.

00:20:52 These people train their bodies for years until they get used to enduring extreme cold.

00:20:57 Of course, they don't do it just for fun.

00:21:04 The advantages of this practice for your health include better blood circulation, increased concentration, and a general feeling of well-being.

00:21:12 And you, how many seconds can you stay barefoot in the snow?

00:21:15 Put your hand in front of you, and put all your fingers together, except your thumb.

00:21:20 Now spread your index finger with your thumb in one direction, and your ring finger with your earring in the other.

00:21:26 Did you succeed?

00:21:27 If so, you would probably be a wonderful musician because the nerves of your palms are well developed.

00:21:33 Are you sensitive when you tickle yourself?

00:21:36 Normally, no, it only works if someone else tickles you.

00:21:40 This happens because the area of the brain that controls the movements predicts the sensations caused by your own movements.

00:21:46 Then it sends a signal to other parts of the nervous system to cancel these sensations.

00:21:51 But some people can tickle themselves.

00:21:54 If you are not one of these people, touching a new texture that the brain does not yet recognize,

00:21:59 or using a leather massager can help stimulate your nerves and relax you.

00:22:04 Take a sheet of paper, a pencil, and sit on a chair.

00:22:08 Stretch out one leg and turn your foot clockwise.

00:22:11 Try to draw the number 6 in the other direction on the paper or in the air, while continuing to turn your foot.

00:22:18 This task is very difficult because the left side of your brain cannot handle two opposite rotations at the same time.

00:22:24 This is why the brain tries to bring all movements in the same direction.

00:22:27 Only a few people succeed in this from the first attempt.

00:22:31 You can also try to write other numbers and observe amusing results.

00:22:35 If you want to check the state of your vestibular system, try this simple trick.

00:22:40 Stand on one foot and close your eyes.

00:22:42 Most people lose balance at least during the first attempt.

00:22:46 Your vestibular system includes many organs and systems throughout your body.

00:22:51 Together, they allow your body to remain balanced in different positions.

00:22:56 This system includes the inner ear and the vision,

00:22:59 which makes it much easier to keep your balance in silence and with your eyes open.

00:23:04 Every day, people use their language to recognize different tastes and communicate.

00:23:09 But it's also a great tool for doing a lot of things.

00:23:13 About 10% of people can touch the tip of their nose with their language.

00:23:17 The current longest language record in the world belongs to the American Nick Storbel.

00:23:22 His language is 10.1 cm long, according to the Guinness Book of Records.

00:23:26 There is also another pretender whose name is in the Indian Book of Records,

00:23:30 with a language measuring 27 cm.

00:23:33 Wow! Can you imagine what he can do with a cornet?

00:23:37 But the language of an adult man is only 8.5 cm long and that of a woman is 7.9 cm.

00:23:44 That's why most people can't do the nose trick as easily.

00:23:49 Making a knot with a cherry tail in his mouth is a popular challenge.

00:23:54 But only a few people manage to do it correctly and quickly.

00:23:58 Al Gliniecki set the world record in June 2014 when he made 14 cherry tail knots in one minute using only his language.

00:24:06 Wow! If you want to try to break his record, train with patience and choose longer stems, about 4 cm.

00:24:13 Many tutorials are available on the Internet.

00:24:16 Stand in front of a mirror, open your mouth and try to roll the sides of your tongue to form a U shape.

00:24:23 65 to 81% of people are native speakers and the majority are women.

00:24:29 Some think it's a genetic ability, but recent studies have shown that people can develop this skill by training.

00:24:36 Keshari Mudra is a yoga term that means to curve the tip of your tongue in your mouth.

00:24:41 Ideally, it should reach the top of the palate and rest at the beginning of the nasal cavity.

00:24:46 This asana helps to refresh the mind and body and to overcome thirst, hunger and anxiety.

00:24:52 Some say it also helps to have lucid dreams if you get used to sleeping by practicing the Keshari Mudra every night.

00:25:00 But most beginners in yoga spend months, even years, reaching the nasal cavity.

00:25:05 So if you can do it right away, you're lucky.

00:25:09 Can you move your ears intentionally?

00:25:12 If so, congratulations!

00:25:14 Because only 22% of people on Earth are able to move an ear.

00:25:18 As for moving both ears at the same time, only 18% are able to do it.

00:25:22 Ear moving was once a common thing for our distant ancestors.

00:25:26 Scientists think they could do a variety of movements with their ears.

00:25:30 The muscle group responsible for ear moving is called the auriculars.

00:25:35 And we don't really need them anymore today.

00:25:37 But some people say that everyone can learn to move their ears.

00:25:42 It only takes time and practice.

00:25:45 Unfortunately, we can't get used to moving our ears to a sound source like dogs and cats do.

00:25:52 Even twins don't have the same language.

00:25:55 The language is made up of a set of powerful, mobile muscles that never get tired.

00:26:00 It contains between 5,000 and 10,000 taste buds.

00:26:03 These little pink and white spots on your tongue are not taste buds.

00:26:08 But each of them has several inside its superficial tissue.

00:26:12 Evolution gave us taste buds so that we could stay alive.

00:26:17 For example, bitter and sour flavors can tell you that you're eating rotten food or toxic plants.

00:26:23 The back of the tongue is more sensitive to bitter flavors.

00:26:26 Which explains why we can spit out bad food before swallowing it.

00:26:30 Salty and sweet flavors tell us if food is rich in nutrients.

00:26:35 By the age of 60, most people lose half of their taste buds.

00:26:40 Indeed, your tongue is pretty cool.

00:26:42 And these taste buds can be used for biometric authentication, just like digital taste buds.

00:26:47 Each of us has a different and unique taste bud.

00:26:50 So if you don't want to reveal your secret identity, you just have to hide your tongue.

00:26:54 It's funny, isn't it?

00:26:55 Why do we have digital taste buds?

00:26:57 Scientists had many different theories about it.

00:27:00 But they now believe that it's because digital taste buds allow the skin to stretch more easily.

00:27:06 They allow us to avoid bulbs, protect the skin from injuries, and improve our sense of touch.

00:27:12 Humans are not the only ones with unique taste buds.

00:27:15 Koalas too.

00:27:17 Only about 7% of people are left-handed.

00:27:20 Left-handed people chew food on the left side of their mouths, while right-handed people do it on the right side.

00:27:26 We lose about 5 kg of skin cells every year.

00:27:29 But don't worry, we replace them quickly.

00:27:32 We produce 15 seconds more cells than there are people living in the United States.

00:27:36 Our body regenerates constantly, and we replace our skin hundreds of times throughout our life.

00:27:41 Yes, the whole body regenerates, except for the teeth.

00:27:44 It's the only part of the body that can't do it.

00:27:47 Our teeth are similar to that of a shark.

00:27:49 Their teeth also have a substance called dentin inside, and they are as solid as ours.

00:27:54 Of course, theirs are more pointed and bigger, but still.

00:27:58 Teeth are part of the human skeleton, even if they are not considered bones.

00:28:02 You spend about 38 days of your life brushing your teeth.

00:28:05 And guess what? You may brush them too much.

00:28:08 Indeed, they can become more sensitive because they wear out the natural enamel.

00:28:12 Your left and right lungs are not the same size.

00:28:15 The right is bigger because the left shares its space with the heart.

00:28:19 Hockey is a symptom that almost all mammals know from time to time, and not just humans.

00:28:24 The record was set by a man named Charles Osborne.

00:28:28 He couldn't stop hockeying for 68 years.

00:28:31 It seems like no one told him about the thing that consists of eating sugar.

00:28:35 There is only one part of your body that does not receive a regular blood supply, and that is your cornea.

00:28:40 It receives oxygen directly from the air.

00:28:43 Our eyes can differentiate 10 million different colors.

00:28:46 The muscles that help our eyes focus on something make about 100,000 movements a day.

00:28:51 If you wanted the muscles of your legs to do the same work, you would have to walk a long way, at least 80 km.

00:28:57 We can't all see infrared light or ultraviolet rays.

00:29:01 Only 1% of us can.

00:29:03 And if you can see one of these rays, it doesn't necessarily mean you can see the other.

00:29:08 Research shows that all people with blue eyes in the world could be related,

00:29:12 or at least share a very distant ancestor.

00:29:15 Scientists have examined individuals with blue eyes from Turkey, India, Jordan and Scandinavia.

00:29:21 They all had the same genetic sequence of the color of their eyes.

00:29:24 They think this characteristic comes from a person with blue eyes whose genes mutated about 10,000 years ago.

00:29:30 Before that, the eyes were simply all different shades of brown.

00:29:34 People with blue eyes are generally a little more sensitive to pain than other individuals.

00:29:39 We blink about 20 times a minute, which means we do it more than 10 million times a year.

00:29:45 The fact that we look like sharks also affects our eyes.

00:29:48 If a part of your eye is damaged, you can replace it with a shark's.

00:29:52 It's convenient, isn't it?

00:29:54 You can't blink with your eyes open.

00:29:56 Try it! It's very difficult to ignore your natural reflexes.

00:29:59 Eels also have their own life, since only one eel lives about 150 days before it dies.

00:30:05 We all know the skin of a chicken when we hear good news, our favorite song,

00:30:09 or when it's ridiculously cold in the freezer.

00:30:12 It's a reflex that comes from our ancestors.

00:30:14 It happens when we release adrenaline.

00:30:17 It makes our hair stand on end and helps us look more imposing.

00:30:21 Scary, huh?

00:30:23 The human brain has 100 billion neurons and a memory capacity of more than 4 Teraoctets, which is huge.

00:30:30 Your brain uses more than a quarter of the oxygen your lungs absorb, and it's mainly composed of water,

00:30:35 more than 75%.

00:30:37 It's still well hydrated.

00:30:39 It's not true that humans use only 10% of their brain.

00:30:43 We use much more than that, even during our sleep.

00:30:46 Most of our brain is constantly active, but we don't ask for all parts at the same time.

00:30:52 Of all species, humans are the only ones that can blush.

00:30:55 This phenomenon is due to an adrenaline rush.

00:30:57 When you feel your face turn red, know that your stomach is too.

00:31:01 It's weird.

00:31:02 When you crack your joints, the sound you hear is that of tiny gas bubbles that are released.

00:31:08 There are gas pockets trapped between your joints, so when you stretch them, they make a dry noise.

00:31:13 Oh, how nice it is!

00:31:15 We use 43 muscles when we frown, but only 17 when we smile,

00:31:22 although scientists still disagree on this point.

00:31:25 Anyway, smile!

00:31:27 An average person consumes about 33 tons of food in their lifetime.

00:31:31 It's the equivalent of 6 elephants!

00:31:33 We breathe about 11,000 liters of air per day, but we can't swallow and breathe at the same time.

00:31:39 Most people need about 7 minutes to fall asleep,

00:31:42 and we're about the only living beings to sleep on our backs.

00:31:45 Randy Gardner decided to try the record for the longest sleepless period.

00:31:49 In 1964, he stayed awake for 11 days, or 264 hours.

00:31:54 I guess he had noisy neighbors.

00:31:57 Of all animals, humans are the only ones with a chin.

00:32:00 When you're thirsty, that means that the water you drink is equal to 1% of your total body weight.

00:32:07 If it exceeds 5%, you can even faint.

00:32:10 During your life, your body goes from 300 bones to 206.

00:32:13 More than half of all your bones are in your feet, ankles, hands and wrists.

00:32:18 The largest human bone is the thigh bone, and the smallest is called the calf bone.

00:32:23 It's inside your glans.

00:32:25 Your nose can recognize a trillion different smells and remember 50,000 of them.

00:32:30 Women smell better than men, and the sense of smell is 10,000 times more developed than the sense of taste.

00:32:36 The surface of our lungs is almost equal to that of a tennis court.

00:32:40 So, what is this sensation you feel when you cross a ridge on a roller coaster and your stomach goes up your throat?

00:32:48 Well, the seat belt keeps your body in place, but your stomach, your intestines and your small internal organs,

00:32:54 they benefit from a little freedom.

00:32:57 It doesn't hurt you, but your nerves can't understand what's going on.

00:33:00 They really think your stomach made a jump in your throat.

00:33:03 We're all bigger in the morning, because during the day, the cartilage between our bones compresses.

00:33:09 It makes us lose about one nail at the end of each day.

00:33:12 The nose and ears are parts of the body that never stop growing.

00:33:16 It's mostly thanks to gravity.

00:33:18 The veins and arteries inside your body are long enough to go around the world twice.

00:33:23 Blood represents about 8% of your body weight.

00:33:27 When you listen to music, the beats of your heart synchronize with the general atmosphere of the song.

00:33:32 So, choose wisely.

00:33:34 Your skin is the largest organ of your body.

00:33:36 It accounts for about 15% of your total weight.

00:33:39 Know that you can burn more calories by sleeping than by watching TV.

00:33:43 Hmm, what if we slept while the TV was still on?

00:33:46 Yes, you can rotate your eyes, but you can't do it without a little training.

00:33:52 Our eyes are equipped with four main muscles that allow them to move from top to bottom and from one side to the other.

00:33:58 There are actually two other muscles that we also use without knowing it.

00:34:01 These muscles help you roll or turn your eyes.

00:34:04 We can focus on something that's spinning, and our eyes will start spinning with it.

00:34:09 This helps us to have a stable image and keep a clear vision, like an autofocus on a camera.

00:34:14 When you move your head from one side to the other and from top to bottom, your eyes move in the opposite direction.

00:34:20 The average human eye has three cones, which allow us to distinguish the red, green and blue spectrums of light.

00:34:27 This gives us the ability to see about a million different colors.

00:34:31 Tetrachromates also perceive ultraviolet tones, because they have four types of cones in their eyes.

00:34:37 Pause the video to test yourself quickly. How many colors can you tell?

00:34:41 There are 39 colors. If you counted more, you might be a tetrachromate.

00:34:51 Some animals, such as bats and dolphins, can see using echolocation.

00:34:57 Some humans can also do something similar called sonar flash.

00:35:01 They can use click-types to create a 3D image of an area in their mind, which allows them to move easily.

00:35:08 The more they click, the more flashes they receive on a room or area, which allows them to better understand the place.

00:35:14 Having absolute hearing is surprisingly rare. Less than one in 10,000 people have this ability.

00:35:20 It allows people to identify musical notes of all kinds with precision.

00:35:24 One of the many advantages of this talent is that it allows people to listen to a song

00:35:29 and to immediately know in what key it is.

00:35:32 People with dysthysiasis are born with a second series of eyelashes that grow from the inner layer of the eyelid.

00:35:40 Although it may seem pretty to some, these extra eyelashes can irritate the eye and cause problems such as light sensitivity,

00:35:47 drooping eyelids, tears and inflammation.

00:35:51 There are a few ways to treat this condition, such as flexible lenses, lasers and cryotherapy.

00:35:57 The Dutch health guru Wim Hof states that his breathing, meditation and training have helped him acquire all kinds of superhuman abilities.

00:36:08 He trained his body to adapt to extreme temperatures and even learned to increase his own body temperature.

00:36:15 He was also able to adapt more quickly to changes in altitude.

00:36:18 He even stated that his training methods and his strict diet and physical regime have improved his immune system.

00:36:26 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:36:32 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:36:39 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:36:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:36:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:36:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:37:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:37:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:37:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:37:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:37:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:37:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:37:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:37:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:37:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:37:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:38:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:38:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:38:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:38:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:38:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:38:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:38:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:38:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:38:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:38:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:39:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:39:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:39:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:39:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:39:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:39:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:39:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:39:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:39:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:39:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:40:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:40:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:40:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:40:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:40:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:40:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:40:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:40:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:40:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:40:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:41:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:41:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:41:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:41:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:41:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:41:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:41:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:41:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:41:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:41:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:42:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:42:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:42:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:42:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:42:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:42:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:42:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:42:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:42:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:42:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:43:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:43:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:43:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:43:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:43:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:43:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:43:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:43:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:43:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:43:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:44:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:44:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:44:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:44:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:44:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:44:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:44:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:44:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:44:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:44:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:45:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:45:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:45:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:45:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:45:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:45:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:45:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:45:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:45:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:45:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:46:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:46:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:46:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:46:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:46:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:46:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:46:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:46:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:46:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:46:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:47:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:47:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:47:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:47:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:47:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:47:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:47:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:47:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:47:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:47:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:48:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:48:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:48:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:48:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:48:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:48:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:48:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:48:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:48:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:48:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:49:04 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:49:10 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:49:16 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:49:22 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:49:28 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:49:34 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:49:40 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:49:46 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:49:52 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:49:58 He also said that he has a better understanding of the body's metabolism and the body's metabolism.

00:50:04 An impressive feat that you won't see because you can't live without your blood vessels.

00:50:10 You think you're resting while you're sleeping, but in fact your brain never stops.

00:50:16 It is in fact more active at night than during the day and processes all the information you've collected.

00:50:21 So have a little respect for it.

00:50:23 The liver is the most active organ in the human body.

00:50:26 It has more than 500 functions and none of them are even clear to scientists yet.

00:50:31 Have you ever wondered why you feel so sleepy after lunch?

00:50:35 Well, it's because your circadian rhythm, which runs at a 24-hour cycle,

00:50:39 asks you to take a nap after 7 hours of sleep.

00:50:42 And food only strengthens this effect.

00:50:45 It's simple.

00:50:46 Teeth and headache are linked by the twin nerves.

00:50:50 They go through the jaw to the head, so that when you feel a toothache,

00:50:55 it usually goes in pairs with that of the head.

00:50:58 You lose calories no matter what you do, even nothing.

00:51:01 A good 8-hour sleep, for example, allows you to lose up to 800 calories.

00:51:06 And yes, you spend energy even while eating.

00:51:09 Like all mammals, we have a reflex that slows down or even stops certain bodily functions

00:51:15 to prevent us from drowning.

00:51:17 This also affects the heart rate.

00:51:19 A person can stay without food for more than 20 days.

00:51:23 However, if you don't sleep for 10 days, your body will simply stop working.

00:51:29 Speaking of sleep, an average person forgets 90% of their dreams.

00:51:34 And that may be a good thing.

00:51:36 Otherwise, imagine how crazy the world would be.

00:51:39 The color of your dreams is influenced by the television you watched as a child.

00:51:44 If you are part of the older generation, who watched television in black and white,

00:51:48 your dreams will most often be monochrome.

00:51:51 If you are used to colored television, your dreams will also be multicolored.

00:51:55 Of the 10,000 people on Earth, one person has his organs in the mirror,

00:51:59 that is, inverted in relation to their usual and normal position.

00:52:03 In other words, the liver would be bigger on the left side,

00:52:07 and the right kidney would be a little higher than the left.

00:52:10 Speaking of kidneys, the left is a little higher than the right.

00:52:13 It's because the liver is bigger on the right side of your body.

00:52:17 People with clear, open blue eyes tolerate pain better than those with dark eyes.

00:52:22 Scientists think this could be due to melanin, which affects the color of the eyes.

00:52:27 The length of your foot is similar to that of your forearm.

00:52:31 If you don't believe me, do the test. I'll wait for you here.

00:52:35 No.

00:52:37 Here are some facts that you may find difficult to digest.

00:52:41 Your stomach has an incredible capacity, which can contain up to 2 liters of liquid.

00:52:47 It's the equivalent of a large bottle of Coke.

00:52:50 It's quite difficult to estimate the amount of solid food you can ingest,

00:52:54 because it is crumbled by your teeth before it reaches your stomach.

00:52:58 There is certainly not enough room for a turkey,

00:53:01 but a good-sized chicken could probably hold it.

00:53:04 If you were asked where your stomach was, you would probably show your belly.

00:53:09 Sorry, but that's not the case. It's actually hidden here, between your ribs.

00:53:14 Scientists think the appendix will eventually disappear.

00:53:18 Nobody really knows why we need it,

00:53:21 but some researchers claim it could have existed to help our ancestors digest tree bark.

00:53:26 Since it is no longer part of our daily diet, the appendix is no longer necessary

00:53:31 and can disappear from our body without any consequences.

00:53:35 The appendix is not the only obsolete part of our body.

00:53:38 Wisdom teeth are not that useful either.

00:53:41 Of course, they were when our ancestors lost some of their teeth,

00:53:45 but the only thing they help us lose now is the money we spend on their extraction.

00:53:51 Almost all of our body is covered in hair, even if we don't notice it.

00:53:55 It even grows in the navel.

00:53:57 Their function seems to be to trap the plushies in their clothes.

00:54:01 Look closely. See?

00:54:03 Your liver acts as your personal bodyguard,

00:54:06 protecting you from toxins and many other things you wouldn't want to have in your body.

00:54:11 It is almost indestructible and can regenerate at any time.

00:54:16 Only 43% of your body really belongs to you.

00:54:19 More than 50% of the cells in your body belong to tiny creatures that live mainly in your intestine.

00:54:26 Yet, even if your own cells are less numerous than those of microbial cells,

00:54:31 you have an average of 100 billion.

00:54:34 You see, you're not that lonely after all.

00:54:37 Keeping this in mind, your own genes represent less than half of what you really are.

00:54:43 If you take all the microbes that live in your body and count their genes,

00:54:47 you will find between 2 and 20 million.

00:54:50 If you sleep, that doesn't mean that your whole body is sleeping.

00:54:54 In fact, your brain sometimes has to work even harder when you sleep.

00:54:58 It needs to process tons of information and reports usually take a lot of time.

00:55:04 Your nose does rest while you sleep.

00:55:06 Surprisingly, your odour is almost inactive at night.

00:55:10 You wouldn't even be bothered if there was a really bad odour in your room.

00:55:14 Odour is one of the most underrated senses.

00:55:17 You wouldn't even be able to enjoy eating without it.

00:55:21 About 80% of the taste of any food is felt through your nose and its ability to recognize odours.

00:55:28 If you pinch your nose while you eat, you will hardly taste anything.

00:55:33 If you don't have odour, you will mostly recognize food by its texture.

00:55:37 So, an onion could seem to taste like an apple.

00:55:40 Try it and leave us a comment with your impressions.

00:55:44 Scientists thought we could distinguish about 10,000 odours, but they were wrong.

00:55:49 Recent research has shown that humans are actually able to distinguish more than a billion odours.

00:55:55 We remember as much as anything else.

00:55:58 Odours can even evoke distant memories.

00:56:01 Your nose not only helps you breathe and detect odours,

00:56:05 it filters air for the throats and the sensitive lungs.

00:56:08 If we inhale dry air, the nose moisturizes it and cools it or warms it if necessary.

00:56:14 In addition, the nose cleanses the air of all impurities.

00:56:17 When you get older, your brain shrinks little by little.

00:56:21 At 75, it is much smaller than at 30 and it starts shrinking at 40.

00:56:26 This happens to everyone and does not affect your mental abilities.

00:56:30 Our brain can store only 7 octaves in its short-term memory.

00:56:35 Don't even try to compare your brain with the capacity of a mobile phone or even the one you had in 2005.

00:56:41 This is why you have such a hard time learning a phone number by heart.

00:56:47 Our short-term memory works like a blackboard.

00:56:50 You can get information, but sooner or later you will miss the space.

00:56:54 To know the capacity of your living memory, do this test.

00:56:58 Ask a friend to write a list of 10 words and read it to you.

00:57:02 Most people remember 7 words or less in the list.

00:57:06 RAM or living memory is an essential thing that we need to do almost all daily activities,

00:57:13 including basic conversations, browsing the Internet and even petting your dog.

00:57:19 Our strongest and most emotional memories are often wrong.

00:57:23 Central memory gives us the confidence necessary to believe that we remember everything,

00:57:28 even if most of the details are invented in our head.

00:57:31 Not only does your brain age, but you also age spectacularly.

00:57:37 Your bones become more fragile and your spine is compressed.

00:57:41 The opposite happens when you rest at night, since your bones relax.

00:57:45 As a result, you wake up a little bigger in the morning than in the evening.

00:57:49 In mammals, only humans can walk on two legs all their lives.

00:57:54 You might think that kangaroos or gorillas move in the same way,

00:57:58 but kangaroos use their tails as a third leg,

00:58:01 and gorillas use their long arms to maintain their balance.

00:58:05 Your bones also participate in metabolism.

00:58:08 As they are mainly made of calcium, when there is not enough of this element in the blood,

00:58:13 the bones begin to reject it in the blood, which balances the body.

00:58:17 The same reaction also works in the opposite direction.

00:58:20 When there is too much calcium in your blood, it is sent to the bones to be stored there later.

00:58:26 The only bone in your body that has the blood of the humerus is the inside of your arm.

00:58:31 That's why the bone that is there is called the humerus.

00:58:34 No, that's totally wrong. Let's move on to the following facts.

00:58:38 The only bones that never grow up are in our ears.

00:58:41 We can hear thanks to these little bones,

00:58:43 because they have adapted to transmit sound vibrations.

00:58:47 Doctors call them the ossicular chain.

00:58:50 One of these auditory bones, the calf, is the smallest bone in your body.

00:58:55 It is not larger than a grain.

00:58:57 Our size, the shape of our body and the color of our skin

00:59:01 depend a lot on where our ancestors lived,

00:59:04 but we can adapt to new conditions even during our own life.

00:59:08 For example, if you move from the plain to the mountains,

00:59:12 you will end up developing more red blood cells to compensate for the lack of oxygen.

00:59:16 And naturally, if you go from a colder climate to a warmer and more sunny climate,

00:59:21 your skin will become darker to adapt.

00:59:24 Our lifespan is programmed in our cells.

00:59:27 They renew and divide constantly,

00:59:29 but they are a kind of internal clock that stops at some point.

00:59:33 Some cells also stop reproducing earlier than others.

00:59:37 On average, cells stop dividing when we reach the age of 100.

00:59:42 This means that if we found a way to deceive our cells to stop the mutiny,

00:59:46 we could potentially live forever.

00:59:50 Body fat is not just an aesthetic nuisance.

00:59:53 It acts as an insulating material, energy reserve and shock absorber.

00:59:58 It is your body that sends the most fat into the region of your waist,

01:00:02 because that's where your internal organs are.

01:00:05 If something happens to you, this layer of fat could protect your vital organs from irreparable damage.

01:00:10 Be careful, your skull is not made of one bone.

01:00:13 It is actually made up of 28 different bones,

01:00:16 many of which have merged to protect your brain.

01:00:19 The jawbone or lower jaw is the only bone in the skull that is not attached to the surrounding bone.

01:00:25 It is attached by conjunctive tissues and muscles.

01:00:28 That's what makes it so mobile.

01:00:30 You can move it in the direction you want.

01:00:33 You can actually chew with your jawbone.

01:00:35 Another word for "mash".

01:00:38 The strongest muscles of your body are not at the level of your arms or legs.

01:00:43 They are in your head.

01:00:45 The masseter is the main muscle responsible for chewing.

01:00:48 It must be the strongest so that you can eat normally.

01:00:52 And you know those muscles that allow you to move your ears?

01:00:55 They are the temporalis, located above your temples.

01:00:58 They also help you chew food.

01:01:01 We have two very fast muscles, which control the closure of the eyelids.

01:01:06 These are the fastest muscles in our body.

01:01:09 Our eyes are fragile and need protection.

01:01:12 So the reflex that protects them must be as fast as lightning.

01:01:15 These muscles can close the eyelids in less than a tenth of a second.

01:01:19 People with double-jointed thumbs can bend them backwards.

01:01:24 It seems very unusual and very few people can do it.

01:01:28 Yet it's quite commonplace.

01:01:30 Even if it looks painful, it doesn't hurt at all for someone with a double-jointed thumb.

01:01:35 We only recognize blue, yellow and red-green colors.

01:01:41 Everything else is a combination of these three colors.

01:01:44 It's impossible to calculate how many of these combinations the human eye perceives.

01:01:48 Because each person has slightly different vision.

01:01:51 But we are around one million combinations on average.

01:01:55 Do you see the topo?

01:01:57 Most people have 12 pairs of ribs, which means 24 ribs in total.

01:02:02 But some have 25.

01:02:04 One in 200 people is born with a so-called cervical rib.

01:02:08 It forms just above the first rib and develops at the base of the neck, above the clavicle.

01:02:15 A cervical rib can be located on the left, right or both sides.

01:02:19 You can have one without even knowing it.

01:02:22 This additional rib does not necessarily form completely.

01:02:25 It can be a thin strip of tissue that even a x-ray cannot detect.

01:02:30 In most cases, this is not really a problem.

01:02:33 Except if it starts to exert pressure on the nerves and blood vessels.

01:02:37 You probably don't think about that when you fill out a form and you come across the "Eye Color" section.

01:02:43 But answering is not that easy for people who have a rare body feature called "heterochromia".

01:02:50 This is a person who has a difference in eye color.

01:02:53 Complete heterochromia means that you have two different colored eyes.

01:02:57 Like a blue eye and a brown eye.

01:02:59 But there is also partial heterochromia.

01:03:02 This means that only part of your iris is of a different color than the rest.

01:03:06 In the United States, less than 200,000 people are affected.

01:03:10 Natural redheads are not as common as you might think.

01:03:13 Only 2% of the world's population are endowed with it.

01:03:16 8 genes are responsible for it.

01:03:18 Scientists used to associate it with a single rare and recessive gene.

01:03:22 Which should be inherited from both parents in two versions.

01:03:26 Then they realized that all people with two versions of this gene do not necessarily have redheads.

01:03:31 So there must be other genes involved.

01:03:34 Do you know what color of eyes is super rare?

01:03:36 Gray!

01:03:37 Most people have brown, blue or hazel eyes.

01:03:40 About 17% of people have blue eyes.

01:03:43 But the probability of having blue eyes and red hair at the same time is about 0.17%.

01:03:48 Less than 1% have gray eyes.

01:03:50 If you have them, it's because of a low melanin level in the anterior layer of your iris.

01:03:55 There are only 43% in the world who have this extremely rare body feature called "golden blood".

01:04:02 About 0.6% of Americans are AB negative.

01:04:06 But it's not the rarest blood type in the world.

01:04:09 In 1961, scientists discovered that an Australian native had a specific blood group.

01:04:15 The one that is totally devoid of certain antigens.

01:04:19 That is to say, proteins or red blood cells.

01:04:22 People who have this exceptional group can give their blood to other people with a rare blood group.

01:04:27 But can only receive it from one of the 40 other people who also have it.

01:04:31 That's why we talk about golden blood.

01:04:33 It's worth its weight in gold.

01:04:35 Another rare body feature is a small hole near the ear.

01:04:39 At first glance, it seems to be a kind of branch.

01:04:42 Some scientists think it could be a kind of evolutionary vestige of the time when we were aquatic creatures.

01:04:49 This small hole is mainly present in one ear, but not both.

01:04:53 Some people have feet similar to those of chimpanzees.

01:04:56 They are curved, flexible and suitable for climbing trees.

01:05:00 Researchers at the University of Boston filmed 400 people walking barefoot.

01:05:05 They concluded that 1 in 13, or 8% of participants, had this feature.

01:05:11 In general, human feet are rigid.

01:05:13 We evolved in this way in order to be able to walk effectively on flat ground.

01:05:18 It's at least what you can learn in school textbooks.

01:05:21 But other monkeys have flexible feet.

01:05:23 This allows them to climb branches when they move in the trees.

01:05:28 The type of foot that looks like that of arboreal monkeys is flexible in the middle.

01:05:33 It bends at the tip of the foot and is halfway between the tip and the heel.

01:05:38 Human feet normally have a joint at this place.

01:05:41 But most people have rigid ligaments that cover the joint.

01:05:45 This is how they keep it rigid.

01:05:47 Rare people who have chimpanzee feet have more flexible ligaments that allow their feet to bend.

01:05:54 Try to move your middle finger or your little finger.

01:05:57 It's impossible to do it without bending your ring, right?

01:05:59 This is how it works for most people.

01:06:02 But some people can completely isolate their ring.

01:06:05 Researchers think it's hereditary.

01:06:07 If you can touch your nose or chin with your tongue,

01:06:10 it means you are part of the 5% of the world's population who can do it.

01:06:15 The tongue of most people can't go that far.

01:06:18 Even if they make an effort.

01:06:19 Some women have a color supervision.

01:06:22 In this case, you can see and distinguish colors thanks to special cells in your eyes called cones.

01:06:28 People usually have three types of cones.

01:06:30 But scientists are particularly interested in tetrachromats.

01:06:34 They think these people have four types of cones.

01:06:37 Thanks to this, they are able to see 100 million different colors.

01:06:41 A team of researchers from the University of Newcastle spent years looking for this kind of person.

01:06:47 Finally, in 2010, they found one of them.

01:06:50 At first, it seems like a magical power.

01:06:52 But it's not always fun.

01:06:54 A tetrachromat said going to the grocery store can be a real nightmare.

01:06:58 Because it's like seeing a bunch of colors coming from every angle.

01:07:02 Some people are born with a double row of cones.

01:07:05 This extra row emerges from the glands of the Mabowmian glands.

01:07:09 One of the examples of celebrities with this rare genetic mutation was Elizabeth Taylor.

01:07:16 Here's something you can try.

01:07:19 Take your right foot off the ground and go in the direction of the needles of a watch.

01:07:23 Can you draw the number 6 with your thumb, without a pencil or paper, just with your toe?

01:07:28 Most people will quickly realize that they have started to move their feet in the opposite direction without even realizing it.

01:07:35 This is partly because the number represents a circle in the opposite direction of the needles of a watch.

01:07:40 This is only in two rare cases when the brain is wired in a different way or thanks to training,

01:07:45 that some people can do it in the opposite direction.

01:07:48 You probably also heard this belief that it is not possible to blink with your eyes open.

01:07:54 Well, it's possible. There are cranial nerves that connect your eyes and your nose.

01:07:59 That's why when they blink, most people automatically close their eyes.

01:08:04 But it is still possible to blink with your eyes open.

01:08:07 And no, your eyes won't come out because of that.

01:08:09 There are people who can make a rustling noise in their head.

01:08:13 All they need to do is stretch their ear or jaw.

01:08:16 We all have this little muscle in our ear.

01:08:18 Its role is to silence certain sounds that can really distract us, for example when we chew.

01:08:24 And some have the ability to bend this little muscle.

01:08:27 In this way, they create a audible growling, as if a little lion was roaring in their head.

01:08:33 Can you fold your thumb backwards?

01:08:35 Then you must have what is called the "autostopper" thumb.

01:08:39 It is a thumb with a double joint that allows them to fold it backwards.

01:08:44 There is no risk of doing it, and it is not something very uncomfortable for them.

01:08:48 It is possible thanks to the distal joints of the thumb.

01:08:52 In some cases, people can only move one thumb backwards, while others can move both.

01:08:58 There is a rare bodily characteristic that makes some people super-tasters.

01:09:03 Genetics plays a role in many things, including in our tasting grandfathers.

01:09:09 About 25% of the world population is part of the category of super-tasters.

01:09:14 Compared to normal people, they have more small visible points on the tongue, called "tasting grandfathers".

01:09:20 This makes them more sensitive to certain tastes, such as sweet, bitter and salty.

01:09:25 They have more pain receptors than the average.

01:09:28 That's why they don't like spicy dishes too much.

01:09:31 Likewise, they probably won't eat a lot of vegetables because the taste will be too bitter for them.

01:09:35 Wisdom teeth were once important, and we don't really need them anymore.

01:09:40 But their absence is actually a fairly rare bodily characteristic.

01:09:44 Nowadays, when wisdom teeth, also called third molar, try to pierce the gums,

01:09:49 in many cases, they lack room.

01:09:52 As a result, they can become bulky inside your mouth.

01:09:56 Many people must get rid of these extra teeth, about 5 million people each year to be precise.

01:10:03 Synesthesia is the phenomenon by which the brain mixes certain senses.

01:10:07 Thus, a person with synesthesia is able to taste music or hear colors.

01:10:13 It is said that Mozart was affected by it.

01:10:15 For example, he saw the D major as a warm and orange tone, and the B flat minor as a dark tone.

01:10:23 This disorder is rare.

01:10:24 About one in 2,000 people are affected, and the majority of them are left-handed or are women.

01:10:30 Imagine that you can remember what you ate at breakfast 15 years ago as if it were yesterday.

01:10:36 Of course, you keep special memories, but there are people who can remember everything that happened to them

01:10:42 until now as clearly as this morning.

01:10:45 If you give them a specific date, they will be able to tell you what they did and where they were in the slightest detail.

01:10:52 This is what is called the "highly superior autobiographical memory".

01:10:56 Only 60 people on the planet have it.

01:11:00 About 6% of people can quickly vibrate their front and back eyeballs.

01:11:07 This does not mean that something is wrong with their eyes.

01:11:10 It's just a single shot that they are able to perform.

01:11:13 Your bones are designed to be very sought after on a daily basis,

01:11:17 and some of them can absorb your weight two or even three times.

01:11:20 It's impressive, but your teeth are even stronger.

01:11:23 When you bite something, your teeth can exert an incredible pressure, up to 90 kilos.

01:11:29 In fact, the enamel is considered to be part of your skeletal system.

01:11:33 Your stomach has an incredible capacity, up to 2 liters of liquid,

01:11:38 which is the equivalent of a large bottle of Coca-Cola.

01:11:41 It is quite difficult to estimate the amount of hard food that you can get into your stomach,

01:11:45 because the food is transformed by your teeth before it reaches the inside.

01:11:49 There is certainly not enough room for a turkey, but a good-sized chicken can probably fit in there.

01:11:54 Every time you turn your hand, the bones inside cross.

01:11:58 Hold your forearm and check.

01:12:01 Now you know where your stomach is exactly.

01:12:04 If you think it's in your stomach, sorry, but you're wrong.

01:12:07 It's here, hidden between your ribs.

01:12:09 You probably already know that your body is made up of about 60% water.

01:12:13 But what is less known is that your bones are also part of it.

01:12:16 About 25% of the bone mass of humans is made up of water.

01:12:20 Scientists believe that the appendix is doomed to disappear.

01:12:23 Nobody really knows why we need it,

01:12:26 but some researchers say it helped our ancestors assimilate the tree bark they ate.

01:12:31 Since it is no longer part of our daily diet,

01:12:34 the appendix could disappear from our body without any consequences.

01:12:37 The human eye has a certain resemblance to the engine of a car.

01:12:41 They both need various liquids to work properly.

01:12:44 An engine needs fuel, and an eye needs tears.

01:12:47 To function properly, tears must be well distributed throughout the eye.

01:12:51 That's why we blink our eyes up to 20,000 times a day.

01:12:54 So we can say that the eye plays a bit like the ice cream maker.

01:12:58 Almost all of our body is covered in hair, even if we don't notice it.

01:13:02 It even grows in the navel.

01:13:04 Their function is to catch the plushies.

01:13:06 The only part of the human body that does not receive any nutrients from blood is the cornea of the eye.

01:13:10 Instead, it is fed by the tears and the liquid that is at the front of your eyes.

01:13:15 If you never knew you had a bodyguard, think about it more seriously.

01:13:19 Your liver is your personal security agent,

01:13:22 which protects you from toxins and many other things you don't want to have.

01:13:25 It is almost indestructible and can regenerate.

01:13:28 When you blush, it indicates an increase in blood flow in your body.

01:13:32 Not only do your cheeks turn a little red, but the wall of your stomach too.

01:13:36 It's because it contains a lot of blood vessels, and when there is more blood than usual, it turns red.

01:13:41 About 43% of your body really belongs to you.

01:13:45 You are made up of more than 50% of tiny little creatures

01:13:48 that live mainly in your intestine and other parts of your body, without ever getting out of it.

01:13:53 Yet, even if your own cells are less numerous than microbial cells,

01:13:57 you still have about 100 trillion.

01:13:59 Don't hesitate to count them if you don't believe it.

01:14:01 The wall of your stomach is renewed every 3-4 days to prevent it from eating itself.

01:14:07 The digestive acids we have can be very harmful.

01:14:11 One thing that surely rests while you sleep is your nose.

01:14:15 You won't feel anything unpleasant in your sleep.

01:14:17 The fact is that your smell is practically deactivated at night.

01:14:21 If there is a smell of nausea in your room, you won't even be disturbed.

01:14:25 We can accidentally digest small plastic objects, glass, coins,

01:14:30 and many others.

01:14:31 They will come out through the digestive tube in 48 hours.

01:14:34 No need to do the test, you can trust us on this.

01:14:37 Scientists used to think that we could distinguish about 10,000 smells.

01:14:42 But recent research has shown that we are actually able to distinguish more than a trillion.

01:14:47 We also remember it better than anything else.

01:14:50 And smells can even evoke distant memories.

01:14:53 We can digest tiny amounts of plastic,

01:14:55 but the human digestive system can't really stand grass.

01:14:59 Animals that brood have special teeth and several stomachs to treat leaves and raw grass,

01:15:04 while we have nothing of all that.

01:15:06 Among mammals, only humans can walk on their two hind limbs and keep this posture all their lives.

01:15:13 You could argue that kangaroos or gorillas move in the same way,

01:15:17 but the first use their tails as a third leg,

01:15:20 and the second use their long arms to keep their balance.

01:15:23 The stomach is the most important defender of the immune system.

01:15:26 The chloride acid in our stomach kills the dangerous food toxins,

01:15:30 viruses and bacteria that enter the food you eat.

01:15:34 This acid can even digest the stomach itself, but the mucous protects it.

01:15:38 Body fat is not totally bad.

01:15:41 It serves as an insulating material, energy reserve and cushion.

01:15:45 Your body sends the most fat into the region of your waist,

01:15:48 because that's where your internal organs are.

01:15:50 If something happens to you, this layer of fat could protect your vital organs from irreparable damage.

01:15:55 We have two really fast muscles, which control the closure of the eyelids.

01:16:01 They are even the fastest muscles in our body.

01:16:04 The eyes are fragile and need to be protected.

01:16:07 That's why when the reflex is triggered,

01:16:09 these muscles close the eyes in about 100 milliseconds, or a tenth of a second.

01:16:13 We only perceive blue, purple, green and red.

01:16:17 Everything else is a combination of these three nuances.

01:16:20 It is impossible to calculate the number of these combinations that the human eye sees,

01:16:24 because each person has slight visual differences.

01:16:27 But there are about a million combinations on average.

01:16:30 Even if you brush your teeth twice a day and never forget to bathe,

01:16:34 your mouth remains one of the dirtiest parts of the human body.

01:16:37 Millions of bacteria live there.

01:16:39 The good news is that most of these bacteria are good for the body

01:16:43 and protect it from bad bacteria and viruses.

01:16:45 The second dirtiest place is your navel,

01:16:48 and that's probably because it's the first place to be ignored.

01:16:51 The fact is that we don't really use it after we're born,

01:16:54 so this neglected area accumulates all kinds of germs, sweat and dirt.

01:16:59 The navel houses more than 2,300 bacterial species,

01:17:02 and it needs special attention.

01:17:05 Do you think you owe your strong hand to your acidulous weight training sessions?

01:17:09 Well, you should thank your little finger.

01:17:12 Well, maybe not, but the ear is the strongest finger.

01:17:15 It is responsible for 50% of the strength of your hand.

01:17:18 Yet the most used finger is the thumb.

01:17:21 It alone provides 40% of the action of the hand.

01:17:24 This probably makes it the most important finger too.

01:17:27 As for your toes, they support about 40% of your weight.

01:17:31 If you've already heard that humans don't really need their toes, that's wrong.

01:17:35 They are also the main support for walking.

01:17:38 Tomatoes have more genes than humans.

01:17:40 But that shouldn't worry you, because it's not the number of genes that count,

01:17:44 but the complexity of their connection.

01:17:46 Nails don't just help us open plastic packages and take off stickers.

01:17:51 If you didn't have a rigid structure to lean on,

01:17:54 you wouldn't be able to judge the firmness you need to hold anything with.

01:17:58 The color of our hair is easily explained by genes.

01:18:01 There are no more than 2% of people in the world with naturally red hair.

01:18:05 They are followed by blondes, about 3%,

01:18:07 and by all varieties of shades of brown, only about 11%.

01:18:11 The vast majority of humans have black hair.

01:18:14 Some hair can stop growing to a certain length.

01:18:17 Hair usually grows for 2 to 7 years, and usually doesn't grow more than 106 cm.

01:18:23 However, a Chinese woman broke the record for the longest hair of all time.

01:18:28 In 2004, her hair was 5.60 meters long.

01:18:32 Even better than Réponse.

01:18:34 When we laugh, think, look at something, dream, move, or do any other activity with our body,

01:18:40 small electrical and chemical signals circulate between neurons along these connections.

01:18:45 Our brain is always active, sometimes even more when we sleep than when we're awake.

01:18:50 And during this process, neurons produce and send more information than all the phones in the world.

01:18:56 You're sitting somewhere outside and an insect lands on your leg.

01:18:59 Your skin has sensory neurons,

01:19:01 and they quickly send the message to your brain at an impressive speed of 193 km/h.

01:19:07 Your brain sends the message to your leg so that it shakes the insect very quickly.

01:19:11 And the speed at which the information travels is even faster, 320 km/h.

01:19:16 Your toes grow about 4 times faster than your fingers.

01:19:20 This happens because we do more with our hands than with our feet,

01:19:23 and so we damage our fingernails more.

01:19:26 There is a good chance that your right hand houses different types of microbes than the left hand.

01:19:31 This happens because they cover our skin from head to toe,

01:19:34 and their variety depends on the thickness of our skin, the humidity, temperature, texture, and chemistry,

01:19:40 which can change when we use our right and left hands in different ways.

01:19:44 Our nails and hair are made of keratin,

01:19:47 a material that we also find in some parts of other animals' bodies,

01:19:51 such as claws, soles, horns, wool, fur, feathers, beaks, turtle shells, or even porcupine spikes.

01:19:59 Our body is made of star dust.

01:20:01 The most complex elements of our body can only come from supernovas.

01:20:06 The first stars were only gaseous amalgams that were attracted together,

01:20:10 and at some point, they started the combustion process.

01:20:13 This eventually led to a nuclear reaction in its center.

01:20:16 The stars that were there just after the Big Bang were more than 50 times larger than our current sun.

01:20:22 Inside it, there was a constant process of manufacturing of elements,

01:20:26 and these big stars burned their fuel faster.

01:20:29 Most of the elements of the human body were formed in these stars for billions of years.

01:20:33 And so we can say that a part of you is immortal.

01:20:36 Not bad, right?

01:20:38 Men and women sometimes seem to belong to completely different species.

01:20:43 You probably know this saying that says that men come from Mars and that women come from Venus.

01:20:48 But let's look at things from the front.

01:20:50 We all have different shapes and sizes, with different personalities, tastes, and even hair colors.

01:20:57 There is certainly no competition.

01:20:59 We are all, and everyone, incredible in our own way.

01:21:03 But we cannot deny these inherent biological differences between male and female bodies.

01:21:09 As for men, they probably don't come from another planet, as far as we know.

01:21:14 But there are a lot of things about the male body that could surprise you more than one.

01:21:18 So put on your doctor's blouse and prepare your stethoscope to examine some unknown facts about the male body.

01:21:25 Testosterone is one of the key factors of the physical attributes considered purely masculine.

01:21:31 This includes a significantly larger hair growth on men's bodies, and especially on their chest and face.

01:21:38 Something less visible, however, is the thickness of their skin, literally.

01:21:43 Thanks to higher levels of testosterone, men have an average skin 20 to 25% thicker than women.

01:21:51 More precisely, it is the deepest layer of our skin, called the dermis.

01:21:56 Men therefore have a skin that is more resistant overall, with a rougher texture.

01:22:01 However, this is not always an advantage.

01:22:04 In fact, men suffer a loss of collagen at a rate more frequent than women, at least in their younger years.

01:22:11 This loss of collagen causes the skin to thin, to sag, and becomes more prone to wrinkles.

01:22:17 Thus, the older men get, the thinner their skin becomes.

01:22:21 At the same time, men's thicker skin allows them to push back the signs of aging longer.

01:22:27 So there are relatively as many advantages as disadvantages.

01:22:30 While women show signs of aging earlier, men's physical aging process, when it occurs, is faster, and the wrinkles are completely hollowed out.

01:22:39 Think of your skin like a rubber band.

01:22:42 The thicker the rubber band, the longer it lasts.

01:22:45 But when wear and tears begin to appear, they are more pronounced.

01:22:49 Suitable care can help you keep a smooth and healthy skin,

01:22:52 the most important being the regular application of sunscreen, even when you are indoors.

01:22:58 You have probably already discussed with your friends or family members the temperature of the room,

01:23:04 to know whether to raise or lower the heating, or let the fan run or not.

01:23:09 Most of the time, men feel a little too hot in a room,

01:23:13 and even if this feeling is not unanimous, it does not mean that they are wrong.

01:23:18 The main cold receptors of the male skin are in a way desensitized.

01:23:23 This does not mean that men are biologically designed to live in the middle of the Arctic,

01:23:28 but their tolerance to cold temperatures is clearly higher.

01:23:32 There is also a big difference in the circulatory system, which influences body temperature.

01:23:38 While women have a higher central temperature and are sensitive to sudden changes in room temperature,

01:23:44 the central temperature of men is less affected.

01:23:47 This is why temperature changes often go unnoticed.

01:23:51 Room temperature is not the only subject on which men and women disagree.

01:23:57 Let's face it, men see a more limited range of colors than women.

01:24:01 So where men could see a basic blue,

01:24:04 women will probably see a more subtle gradient, like lavender blue.

01:24:09 At the same time, men have a better vision of distant mobile objects.

01:24:13 Thus, the difference between the way men and women see the world goes beyond color.

01:24:18 Studies suggest that the physiological cause of this difference in optics between the two sexes

01:24:23 is, once again, testosterone.

01:24:26 Men have more testosterone receptors than women,

01:24:29 which leads to a different organization of neurons in the visual cortex.

01:24:34 A theory explaining this lies in evolution,

01:24:37 more precisely, that of our ancestors hunter-gatherers.

01:24:41 It is possible that the vision of the distant is benefited by men to distinguish prey and distant predators.

01:24:47 Conversely, women may have developed a more distinct visual palette of prey for food and hunting.

01:24:54 Today, although hunting and hunting practices are less common,

01:24:59 men can still spot their favorite restaurant from afar.

01:25:02 Have times really changed?

01:25:05 In fact, to help them swallow their favorite meal, men also have larger teeth.

01:25:10 Although what is considered masculine or feminine in terms of teeth is entirely subjective,

01:25:15 men tend to have a considerable advantage in the matter.

01:25:20 This is particularly noticeable in incisors and canines,

01:25:24 which have a larger diameter and are more pointed.

01:25:27 This means that the typical masculine smile is more voluminous and more square.

01:25:32 The explanation is once again in the physiology of evolution.

01:25:36 Our primitive ancestors had a fairly conflicting hierarchy,

01:25:40 which meant that males needed to affirm their domination.

01:25:44 Just like modern monkeys, it is possible that these males like to show their claws to intimidate other males and potential threats.

01:25:52 Larger canines were the sign of a more formidable individual.

01:25:56 Although we no longer find such behavior among modern men,

01:26:00 their larger teeth can explain larger jaws,

01:26:03 often considered a feature associated with masculinity.

01:26:07 On the contrary, spreading out all his rattle is often perceived as a sign of joy.

01:26:12 Larger teeth are not the only masculine trait in the mouth.

01:26:17 Let's talk about this unelegant snoring noise that can occur when some people sleep.

01:26:22 Although snoring is as well attributed to men as to women,

01:26:26 almost twice as many men are subject to snoring.

01:26:29 Studies on sleep show that 4 out of 10 men are likely to be regular snorers,

01:26:35 against 24% among women.

01:26:37 Although there are a multitude of causes for chronic snoring,

01:26:41 male biology is the main responsible for these statistics.

01:26:45 By biological design, most men have larger upper respiratory tracts and lower larynx.

01:26:52 This results in a large space at the back of their throat where snoring is amplified.

01:26:57 Men also tend to have more abdominal body fat,

01:27:02 probably due to a higher consumption of carbohydrates.

01:27:05 Weighing more, especially at the neck, chest and thorax,

01:27:11 exerts more pressure on the respiratory tracts, which increases the risk of snoring.

01:27:16 Although their partner probably doesn't appreciate it,

01:27:19 in most cases snoring is relatively harmless.

01:27:23 However, it can also be a sign of underlying health problems,

01:27:27 so it's worth taking an interest in it.

01:27:29 Now, have you ever wondered why men generally have a lower voice?

01:27:34 This is naturally related to the throat.

01:27:37 The largest size of their larynx contributes to another unique feature of the male body,

01:27:43 the Adam's apple.

01:27:45 This cartilage bump that protrudes from the throat

01:27:48 is formed when the larynx grows behind it, pushing it outward.

01:27:52 By the way, some women with a larynx larger than average

01:27:56 can also develop an Adam's apple.

01:27:59 However, there is still a difference in the sound of the voice.

01:28:02 The larynx is what produces our voice.

01:28:05 A larger larynx creates deeper and louder sounds,

01:28:08 because there is more room for the vibrations to resonate.

01:28:11 And since the size of the Adam's apple depends on the size of the larynx behind it,

01:28:15 a larger Adam's apple can also mean a deeper voice.

01:28:19 The cartilage that constitutes the Adam's apple acts like a shield

01:28:23 to protect the larynx from injury.

01:28:25 Beyond that, it does not perform any proper function.

01:28:29 We do not recommend that you do a musical duet with someone who has a larger Adam's apple.

01:28:34 There is a good chance that you will have trouble singing higher than him.

01:28:38 As long as we are on the face, let's take a look at the eyelashes.

01:28:41 Did you know that men are more likely to have longer and thicker eyelashes?

01:28:46 Eyelashes are primarily used to protect the eyes against various elements.

01:28:49 In addition, they are considered an attractive element of the face.

01:28:53 So, sorry ladies, men win this round most of the time.

01:28:58 But why do men tend to have longer eyelashes?

01:29:02 Well, this is due to the common cause of most unique male characteristics,

01:29:07 testosterone.

01:29:09 As we have already mentioned, men have higher levels of testosterone,

01:29:13 which affects the growth of their body hair, and this includes eyelashes.

01:29:18 This also brings us back to their primary function.

01:29:21 Eyelashes are a form of protection.

01:29:23 They help keep the eyes hydrated, to avoid dryness and irritation.

01:29:28 They also protect them from harmful particles suspended in the air,

01:29:31 such as dirt and dust.

01:29:34 Eyelashes are therefore one of the rare characteristics of our body,

01:29:37 which combine aesthetics and functionality.

01:29:40 Despite all our biological differences, there are many common elements in men and women,

01:29:45 and even more than you think.

01:29:47 To begin with, it is time to stop thinking that spectacular hormonal changes

01:29:52 are exclusively feminine.

01:29:54 But while women are fully aware of the challenges their bodies must face

01:29:57 when these changes occur, men are more unaware.

01:30:01 This may not be as frequent as on a monthly basis,

01:30:04 but about 26% of men know these regular hormonal changes.

01:30:09 Although the biological cause may be completely different,

01:30:12 the symptoms can be remarkably similar.

01:30:15 The cause of these changes is still testosterone.

01:30:19 Men's testosterone levels tend to go up and down

01:30:23 depending on the season of the year.

01:30:26 When these fluctuations occur,

01:30:28 this can lead to side effects such as fatigue, cramps,

01:30:32 increased sensitivity, irritability and mood swings.

01:30:36 Most of us experience this.

01:30:38 We should all be more understanding of each other

01:30:42 when those around us are experiencing hormonal changes.

01:30:48 Here is a young man in a suit.

01:30:50 He has a secret.

01:30:51 He is in the bathroom, standing in front of his mirror,

01:30:54 and he washes his face in cold water to show off.

01:30:57 There is no one else here but him, but he is not alone.

01:31:00 Our friend looks nervous.

01:31:02 He taps his cheeks, looks in the mirror and says,

01:31:04 "Don't worry, we'll get by.

01:31:06 We've been doing this for so long, we'll win."

01:31:09 If he says "oh", it's not because he has a double personality.

01:31:13 And no, he doesn't address another person with a small microphone either.

01:31:17 He says "oh" because he knows something.

01:31:19 Technically speaking, he is not just a human,

01:31:22 he is a group of billions of living creatures.

01:31:25 He, you and all of us on Earth are not exactly what we think we are.

01:31:30 Your body is made up of human cells, only 43%.

01:31:33 The remaining 57% are microbes and bacteria.

01:31:37 This man is now going on stage to reveal this secret to us.

01:31:41 Get on the scale.

01:31:42 Do you see the figure?

01:31:43 Subtract a little more than half of that.

01:31:45 Here is your real weight.

01:31:47 All the rest is just a microscopic organism.

01:31:49 It's hard to believe because in this case,

01:31:51 your body should constantly change shape and disintegrate into tiny particles.

01:31:56 You will see your skin palpitate and move continuously.

01:31:59 Fortunately, this does not happen for two reasons.

01:32:02 First, the microbes are tiny, their movements are not visible.

01:32:07 Secondly, most of this microbial world is in a dark place that we cannot see.

01:32:12 A place without access to oxygen.

01:32:14 In our intestines, this is where billions of little creatures walk around us.

01:32:19 Do you feel a little overwhelmed all of a sudden?

01:32:22 Some of these creatures were already there before our birth.

01:32:25 But most are colonists who have entered you with food and water.

01:32:30 At the surface of your body, all the microbes come from the environment.

01:32:34 Each corner of your skin is covered with microbes.

01:32:37 Whatever your efforts, it is impossible to get rid of them.

01:32:41 There are more microbes than human cells.

01:32:44 Our genome is composed of about 20,000 genes.

01:32:47 The number of genes of microbes present in the human body is between 2 and 20 million.

01:32:51 This means that technically, we are not so many people as microbes.

01:32:56 But it does not matter, the genome of microbes completes ours.

01:32:59 Such a model of existence is a real opportunity mine for medicine.

01:33:03 Human microbiomes include bacteria, fungi and other microorganisms.

01:33:08 They are divided into many species and each type fulfills its own function.

01:33:12 Some microbes are responsible for extracting vitamins from food.

01:33:16 Others help decompose harmful substances.

01:33:19 Another type helps your stomach to digest food.

01:33:22 A distinct group regulates your immune system, protects it against worms, parasites and viruses.

01:33:28 Some control your weight.

01:33:30 In simple terms, microbes improve your life, help your body to function and have a great influence on your health.

01:33:36 There are microorganisms that cause diseases.

01:33:39 They alter immunity or affect vital organs.

01:33:42 Imagine that you know exactly which bacteria are responsible for your poor health.

01:33:47 Then you find a way to get rid of them.

01:33:49 It can be a pill that will be a poison for these microbes.

01:33:52 You take it and the remedy removes all harmful parasites inside your body.

01:33:57 A disease can also appear due to a lack of good microbes.

01:34:01 This is one of the ways that doctors treat and cure people all over the world.

01:34:05 Let's say you found a group of microbes that help strengthen the muscles.

01:34:09 Then you discover which oligoelements help these bacteria to work faster and more efficiently.

01:34:15 You add these vitamins to your food or you just buy a pill containing a billion of these microbes.

01:34:21 Result! Your muscles develop twice as fast.

01:34:24 The presence or absence of certain microbes indicates the state of your body as a whole.

01:34:28 A sample of your microbes can reveal your health level or the presence of a disease.

01:34:34 So anyone can help their body to get better not only thanks to genetics but also thanks to microbial medicine.

01:34:41 The study of human microbes is cheaper, more efficient and faster than genetic modifications, which are complex and expensive.

01:34:48 This field is just starting to develop but we have already made some discoveries.

01:34:52 In the past, humanity thought that microbes were enemies.

01:34:55 We have invented many ways to destroy bacteria and viruses.

01:34:59 But in addition to harmful microbes, these remedies get rid of the good ones.

01:35:03 Now, scientists have understood that microbes can both save lives and destroy them.

01:35:08 So they have launched large-scale research on this subject.

01:35:12 Let's look at the case of a giant panda.

01:35:14 This animal, which has a large amount of fat under the skin, is omnivorous.

01:35:18 It rarely eats meat.

01:35:20 Its diet is mainly made up of bait and bamboo shoots.

01:35:24 But in winter, there is nothing like that, so pandas feed on bamboo leaves.

01:35:28 This food is low in calories.

01:35:30 It contains almost no protein.

01:35:33 But pandas have not lost weight after a cold winter.

01:35:37 Recently, scientists have discovered the reason for this.

01:35:40 It is thanks to a unique microbiome.

01:35:42 Every winter, a large number of unique bacteria are born in their intestines.

01:35:47 These microbes extract and synthesize the useful substances found in bamboo leaves better than others and also preserve the weight of the panda.

01:35:55 Scientists have put these bacteria in mylos.

01:35:58 The little rodents have started to gain weight much faster.

01:36:01 Burgers, cakes and other rich foods contain calories and promote the development of colonies of microbes that contribute to weight gain.

01:36:09 These millions of species of microbes have millions of different functions.

01:36:13 In theory, each of these functions can be used for the good of humans.

01:36:17 Imagine that you need to lose or gain weight and that you just add these microbes to your breakfast.

01:36:23 Do you want to sleep better or fight drowsiness?

01:36:25 Drink microbes that will have an effect on the production of sleep hormones.

01:36:29 Do you want to strengthen your bone tissue? No problem.

01:36:32 Bacteria are not only inside our body.

01:36:35 They are everywhere.

01:36:36 A large part of the planet is made up of microbes.

01:36:39 These tiny organisms multiply constantly.

01:36:42 Look, there are a billion of them on your keyboard.

01:36:45 A bacteria increases in size and divides into two bacteria.

01:36:48 After a few minutes, these two new bacteria increase in size and divide in turn.

01:36:53 Four microorganisms appear.

01:36:55 Each of them divides into two.

01:36:57 The colony of bacteria develops rapidly.

01:36:59 With such a rapid reproduction, a microbe can make a ton of descendants in just 24 hours.

01:37:05 After 5 days, these bacteria will fill all the seas and all the oceans.

01:37:10 They will weigh more than the entire planet.

01:37:12 In ideal conditions, the bacteria could take over the whole world.

01:37:16 However, this will never happen.

01:37:18 The conditions are not united for an uncontrolled bacterial growth.

01:37:21 The speed at which they multiply is equal to the speed of their destruction.

01:37:25 Dryness, water, light, high temperatures, gases, humidity, all these phenomena help control their population.

01:37:33 At the same time, microbes are responsible for most of the chemical reactions on Earth.

01:37:38 An old rotten apple on the ground because of microbes and bacteria.

01:37:41 Mold forms on bread because of microorganisms.

01:37:45 But they do not just exist and affect the state of all living materials and other creatures.

01:37:50 A never-ending war for survival is constantly going on in the world of microorganisms.

01:37:56 Giant bacteria absorb the smallest ones.

01:37:58 Spiky microbes attack long microbes.

01:38:01 There are also viruses that penetrate bacteria to infect them with their cells.

01:38:06 A small ball containing a virus can destroy an entire colony of microbes.

01:38:11 Viruses multiply and take up more and more territory until they fall on strong immune cells.

01:38:17 There are also creatures that look like robots.

01:38:20 They look like diamonds with mechanical legs.

01:38:24 Despite this unusual appearance, they are 100% natural.

01:38:28 They are called bacteriophages.

01:38:30 Their only purpose is to destroy all bacteria.

01:38:33 But bacteriophages are an additional protection of the planet against the uncontrolled reproduction of microbes.

01:38:39 When some microorganisms multiply, they leave waste in decomposition.

01:38:44 These waste are harmful to humans.

01:38:46 Bacteriophages fight these microbes and save our lives.

01:38:50 The coolest thing is that these defenders do not seek to take control of the planet.

01:38:54 They only attack bacteria.

01:38:56 Every second, billions of microbes fight billions of bacteriophages on all surfaces, like in a video game.

01:39:04 The bacteriophage jumps on the bacteria and injects its genetic code inside.

01:39:09 This code is made up of separate elements that connect to each other inside the body of the microbe to form a new bacteriophage.

01:39:17 After that, it destroys the bacteria inside and attacks the next one.

01:39:21 Look carefully at the tip of your finger. There are a lot of lives in this place.

01:39:25 The strongest survive, the weak ones disappear.

01:39:28 Wash it and new bacteria will arrive with water.

01:39:31 Then wipe your wet finger with a towel and new microbes will jump on you.

01:39:36 The battle is endless, and it's only the tip of your finger.

01:39:39 Inside your body, some bacteria fight for your health against microbes that want to harm you.

01:39:45 Some microbes in our intestines can be responsible for our good or bad mood.

01:39:49 There are also parasitic bacteria that can affect our brain, our way of thinking and our emotions.

01:39:55 Some creatures control the behavior of animals and insects.

01:39:59 Scientists are constantly making discoveries in the world of microorganisms.

01:40:04 These bacteria are therefore masters of our world.

01:40:07 They appeared long before humans and the first animals.

01:40:10 And most likely, they will remain after us.

01:40:13 There is the matter to think about.

01:40:15 Here are some facts that you may have trouble digesting.

01:40:21 Your stomach has an incredible capacity, because it can contain up to 2 liters of liquid.

01:40:29 This is equivalent to a big bottle of Coca-Cola.

01:40:32 It is difficult to evaluate the amount of solid food that would hold it.

01:40:36 Because they are crushed by your teeth before reaching your stomach.

01:40:40 There is certainly not enough room for a turkey, but a chicken should hold it.

01:40:45 If you are asked where your stomach is, you may point to the middle of your stomach.

01:40:50 But it's wrong. It's here, hidden under your ribs.

01:40:55 Scientists think that the appendix will eventually disappear.

01:40:59 Nobody really knows what it is for.

01:41:01 But some researchers say that it could have helped our ancestors to digest the bark of trees.

01:41:07 As it is no longer part of our diet, the appendix would therefore no longer be necessary.

01:41:12 And it can disappear from our body without any consequence.

01:41:16 The appendix is not the only obsolete part of our body.

01:41:20 Our wisdom teeth are no longer useful to us either.

01:41:23 They were when our ancestors lost some of their teeth.

01:41:26 But the only thing they help us lose now is the money needed to extract them.

01:41:32 Almost our whole body is covered in hair, even if we do not see them.

01:41:37 There are even in the navel. They are used to catch the fleas. Not true?

01:41:42 Your liver acts as a bodyguard by protecting you from toxins and everything you would not like to see hanging in your body.

01:41:49 It is almost invincible and can even regenerate.

01:41:52 Only 43% of your body really belongs to you.

01:41:56 More than half of the cells in your body belong to small creatures, mainly living in your intestines.

01:42:02 But even if your cells are inferior, you have an average of 100 billion, so you're not alone.

01:42:09 Your own genes also represent less than half of what you are really made of.

01:42:15 If we take all the living microbes in your body and add their genes, we will have between 2 and 20 million.

01:42:22 When you sleep, it does not mean that your whole body is sleeping.

01:42:26 In fact, your brain works even harder when you sleep, because it processes tons of recorded information during the day.

01:42:34 Your nose, meanwhile, rests when you sleep, which means that your odor is practically deactivated at night.

01:42:41 You would not even be bothered if the worst smell entered your room.

01:42:45 It leaves you thinking.

01:42:47 The nose is one of the most underestimated parts of the body. Without it, we could not even appreciate what we eat.

01:42:54 About 80% of the taste is due to the nose and its ability to recognize smells.

01:43:00 If you cover your nose while eating, you will have almost no flavor.

01:43:04 In the absence of odors, you will recognize the foods just by their texture.

01:43:08 So an onion would look identical to a big sweet apple.

01:43:12 Before, scientists thought that we could distinguish about 10,000 smells.

01:43:17 But recent research has shown that we were actually able to distinguish more than a billion.

01:43:23 We memorize them better than anything else.

01:43:26 And smells can even evoke distant memories.

01:43:29 Your nose not only helps you breathe and sense smells.

01:43:33 It also filters air for the throat and lungs. By inhaling dry air, the nose moistens, refreshes or warms it up if necessary.

01:43:41 In addition, it gets rid of impurities.

01:43:44 As we age, the size of our brain decreases gradually.

01:43:48 At 75, it is much smaller than at 30.

01:43:51 And it starts to shrink at the age of 40.

01:43:54 This happens to everyone and does not affect our mental capacity.

01:43:58 The brain can only store 7 bytes in its short-term memory.

01:44:03 Do not try to compare it to the memory of a phone, even that of an old model.

01:44:07 This explains why it is so difficult to learn a number by heart.

01:44:11 Our short-term memory works like a blackboard.

01:44:14 You can remember some information, but sooner or later you will miss two places.

01:44:19 To check it, try this test.

01:44:22 Ask a friend to write a list of 10 words and read it to you.

01:44:26 Most people remember less than 7 words from this list.

01:44:30 Your living or working memory is an element you need to accomplish almost all your daily activities,

01:44:36 including basic conversations, browsing the Internet and even taking care of your dog.

01:44:42 Our most memorable emotional memories are often erroneous.

01:44:46 Our central memory makes us believe that we remember everything, even if most of the details are invented by our mind.

01:44:54 It is not only the brain that shrinks as it ages. You shrink too.

01:44:59 Your bones become more fragile and your spine is compressed.

01:45:03 A similar thing happens during the night. Your bones relax.

01:45:07 So when you wake up in the morning, you are taller than when you go to bed.

01:45:11 Among mammals, only humans walk on two legs all their lives.

01:45:16 We could think that kangaroos and gorillas too,

01:45:19 but kangaroos use their tails as a third leg and gorillas use their arms to keep balance.

01:45:26 Your bones also participate in your mechanism.

01:45:29 As they are mainly made of calcium, if you don't have enough in your blood,

01:45:33 they release it in your bloodstream to keep balance.

01:45:37 The same reaction also works in the opposite direction.

01:45:40 If you have too much calcium in your blood, it goes into your bones to be stored there.

01:45:46 The only bone to have the sense of humor is in your arm. It's the humerus.

01:45:51 Ok, it's not very funny.

01:45:53 The only bones that never grew up are in our ears.

01:45:57 We can hear thanks to these small bones that have adapted to transmit sound vibrations.

01:46:02 Doctors call them the "austicular chain", one of these auditory bones.

01:46:06 The calf is the smallest bone in the entire human body. It is not bigger than a grain of rice.

01:46:12 Our size, our physical characteristics and our skin color depend on where our ancestors lived.

01:46:18 But we can adapt to new conditions during our own life.

01:46:22 For example, if you go to live in the mountains, you will create more red blood cells to compensate for the lack of oxygen.

01:46:29 And if you go from a cold climate to a warmer and more sunny climate, your skin will become darker.

01:46:35 Our lifespan is programmed in our cells. They are constantly renewing.

01:46:40 But they have a kind of internal timer that stops at some point.

01:46:44 Some cells stop renewing earlier than others.

01:46:47 On average, cells stop dividing around the age of 100.

01:46:51 If we could find a way to prevent this timer from stopping, we could live forever.

01:46:57 Body fat is not just a problem. It also serves as an insulator, a reserve of energy and a shock absorber.

01:47:07 It is in the region of the waist that your body stores the most fat, because this is where your internal organs are.

01:47:13 In case of shock, this layer of fat can protect your vital organs from irreparable damage.

01:47:19 Your skull is not made up of a single bone, but of 28 different bones, most of which are welded together to protect your brain.

01:47:27 The lower jaw is the only bone in the skull that is not attached to the bone around it.

01:47:35 It is connected to it by conjunctive tissue and muscles.

01:47:39 This is what makes it so mobile. You can move it in all directions.

01:47:44 The most powerful muscles of your body are not in your arms or legs, but in your head.

01:47:51 The masseter is the main muscle responsible for chewing.

01:47:55 And it must be powerful to help you eat normally.

01:47:59 And you see those muscles that help you move your ears?

01:48:02 These are the temporal muscles. They also help you chew.

01:48:06 We also have hyper-fast muscles that control the closure of the eyelids.

01:48:11 These are the fastest muscles of the whole body.

01:48:14 Our eyes are fragile, so the reflex that protects them must be as fast as lightning.

01:48:20 These muscles can close your eyelids in less than a tenth of a second.

01:48:24 People with double-jointed thumbs can bend them backwards.

01:48:29 Very few people can do it, but it's still quite normal.

01:48:32 Even if it looks painful, it doesn't hurt at all for someone with a double-jointed thumb.

01:48:38 We only distinguish blue, green, yellow and red colors.

01:48:43 Everything else is a combination of these three colors.

01:48:46 It is impossible to calculate the number of combinations that the human eye can see,

01:48:50 because each person has a slightly different vision.

01:48:53 But there are on average a million combinations.

01:48:56 So, what makes your vision so clear?

01:48:59 The cornea is the only part of your body that contains living cells and does not have a blood vessel.

01:49:07 It receives nutrients and oxygen directly from the lacrimal fluid outside

01:49:12 and the thick tissue that is between the corneas inside,

01:49:17 as well as nerve fibers connected to the cornea.

01:49:20 This is why contact lenses have first constituted a potential problem.

01:49:25 The oldest ones reduced the oxygen supply, because the cornea receives mainly oxygen from the outside.

01:49:31 This problem was solved, or at least reduced,

01:49:34 when hydrogel silicone lenses arrived on the market.

01:49:38 The other parts of the body devoid of blood vessels are the nails,

01:49:42 the hair, the outer layers of the skin and the teeth.

01:49:46 Have you noticed that your sweat sometimes smells like onions after sports?

01:49:51 Don't worry, there are two types of sudoriparous glands in your skin.

01:49:56 The first type of gland is located on certain parts of your body,

01:50:00 such as the wool region and the armpits.

01:50:03 They produce a specific oily flow, which is a response to certain emotional experiences.

01:50:09 Another type of sudoriparous gland is much more common.

01:50:12 They are distributed throughout the body and are responsible for the specific sweat you get after sports.

01:50:19 This sweat cools your body by evaporating from your skin.

01:50:23 It's 99% water, so it's practically odorless.

01:50:27 At least when it leaves the pores and reaches the surface of the skin.

01:50:32 But there are many types of bacteria on the human skin,

01:50:35 and they feed on nutrients contained in this sweat as well as squamous.

01:50:40 One of the by-products of this process is a specific chemical product,

01:50:43 whose smell can sometimes strongly resemble that of onions.

01:50:47 You may have noticed that you produce more saliva when you run,

01:50:51 especially if it's a short jog in cold weather.

01:50:55 But if you run a marathon and it's nice and warm outside, you'll produce less saliva.

01:51:01 It's your body that tries to compensate for the effect of dehydration

01:51:05 since you breathe much more through your mouth.

01:51:08 But your body dehydrates more over long periods.

01:51:13 That's why it tries to conserve water by reducing the production of saliva.

01:51:18 Each training, however intense it is,

01:51:21 leads to the secretion of a specific type of protein.

01:51:25 It makes the saliva more viscous and sticky,

01:51:28 which explains why you may feel your mouth even drier after your training.

01:51:34 Humans see the world with a 15-second gap,

01:51:37 which means your brain constantly leaves you a little in the past.

01:51:42 This helps you stabilize your vision of the world around you.

01:51:46 Your eyes receive a huge amount of visual information.

01:51:49 Yes, literally millions of colors, shapes and movements

01:51:53 are constantly evolving wherever you are.

01:51:56 It's not an easy task for your brain to process all of this.

01:51:59 The visual world is constantly changing

01:52:02 due to changes in point of view, light and other external factors.

01:52:07 The input of images into your brain also changes

01:52:10 because you have to blink your eyes and your head,

01:52:12 your eyes and your whole body are always moving.

01:52:16 Your brain therefore had to establish a mechanism

01:52:19 that can create an imaginary stability.

01:52:22 It automatically smooths your visual inputs.

01:52:25 It does not analyze each little visual cliché.

01:52:28 It's like a time machine.

01:52:31 You actually perceive a synthesis of things

01:52:33 that you have seen over the last 15 seconds at a given moment.

01:52:37 The brain groups objects together

01:52:39 so that they seem more similar to each other.

01:52:41 That's why it makes you believe you're in a stable environment.

01:52:45 If your brain kept you up to date in real time,

01:52:48 the world would seem very, very chaotic to you,

01:52:51 with constant changes in movement, light and shadow,

01:52:54 which would probably give you the impression of hallucinating all the time.

01:53:00 Your bones are very strong, but your teeth,

01:53:03 which we consider to be part of the skeletal system,

01:53:06 are even stronger.

01:53:08 This is due to the enamel, the hard outer layer of the teeth.

01:53:12 Enamel protects the delicate tissues and nerves inside the teeth.

01:53:18 Remember to burn calories when you think,

01:53:21 when you rest and do not do any particular activity

01:53:25 except the essentials, such as digesting, breathing and warming up.

01:53:30 This is the moment when your brain uses up to 20 to 25% of your body's total energy.

01:53:36 This means that your body burns about 350 to 450 calories a day

01:53:41 by doing practically nothing.

01:53:44 We are not the only ones in the animal kingdom to have a mechanism of this type.

01:53:48 Some small mammals, such as the tiny Wistiti pygmy

01:53:52 and the tiny arboreal musarene,

01:53:55 devote the same percentage of their total body energy to their brains.

01:53:59 Most of the energy consumed by the brain is used to help these cells, neurons,

01:54:03 communicate with each other.

01:54:05 They do so through chemical signals that the brain transmits through the synapses,

01:54:09 these special cellular structures.

01:54:12 The brain therefore directs a lot of energy to the synapses

01:54:15 to make them work.

01:54:17 Your brain never really rests.

01:54:20 Even when you sleep, some parts are active.

01:54:23 Your brain therefore needs its fuel to function

01:54:26 and you burn essentially calories during your sleep.

01:54:29 The more demanding mental tasks you do during the day,

01:54:33 the more calories you burn.

01:54:35 So if you don't exercise today, save at least a few bucks.

01:54:40 Do you like to eat your ice cream?

01:54:42 Sometimes it's super nice, but if you do it often,

01:54:45 you must know this sensation of brain freeze.

01:54:49 It's a rather intense and unpleasant sensation

01:54:52 that occurs at the front or on the sides of your head

01:54:55 just after you've had or eaten something very cold,

01:54:58 like an ice cream, an ice cream or a water ice cream.

01:55:01 Some people even experience a similar sensation

01:55:04 when they're just exposed to the cold air.

01:55:07 Scientists don't know yet exactly why this happens,

01:55:10 but one theory is that the cold substance

01:55:13 stimulates a group of nerves located at the back of the brain.

01:55:17 According to another theory, the blood vessels of the palate and the sinuses

01:55:21 contract quickly due to the drop in temperature in the mouth

01:55:24 before dilating again.

01:55:27 Brain freeze is not something dangerous

01:55:30 that you should seriously worry about.

01:55:32 And no, sitting at a table,

01:55:35 moaning or shaking your head in your hands won't help you much.

01:55:38 Some people like to sleep a lot.

01:55:41 Hey, I'm a guilty pleb.

01:55:44 Some people have a disease called

01:55:47 "Family Natural Sleeper Syndrome",

01:55:50 which means that they're immune to lack of sleep.

01:55:53 About 1% of our population is affected.

01:55:56 They may lack sleep, but they feel pretty good.

01:55:59 They don't have a problem sleeping just 6 hours a night.

01:56:02 This low amount of rest would destroy most people after a few nights.

01:56:06 The human eye normally has three cones.

01:56:09 This means that we can recognize about 1 million different shades

01:56:13 of green, red and blue.

01:56:16 But some people with a rare disease called tetrachromatia

01:56:20 have four cones in their eyes.

01:56:23 This allows them to see the ultraviolet shades,

01:56:26 which means that they can distinguish 100 million different colors.

01:56:30 Did you know that your skeleton is all wet?

01:56:33 I mean that your whole body is mainly made up of water, up to 60%?

01:56:38 This liquid is not only in your organs, your muscles and your skin.

01:56:42 It's also in your skeleton.

01:56:45 Your bone mass is made up of about a third of water.

01:56:49 The human body contains a surprising network of hidden cells.

01:56:52 Blood vessels are really small, but if you could align them all,

01:56:56 you'd get something huge.

01:56:59 Your whole body has a network of 96,560 km of blood vessels.

01:57:03 One way to keep your network healthy is to eat well.

01:57:07 Have you ever wondered why our distant relatives, the primates,

01:57:11 are so much stronger than us?

01:57:14 In many ways, our bodies are very similar.

01:57:17 Look at the muscular structure of chimpanzees, for example.

01:57:20 But our closest primate relatives are about 1.35 times stronger than us.

01:57:25 The human body has developed more muscle fibers at slow contraction

01:57:30 than the rest of the primates.

01:57:32 This type of muscle fiber is less powerful,

01:57:35 but it allows us to last longer than other primates

01:57:38 and to do things like hunt and feed,

01:57:41 activities that have helped our distant ancestors survive.

01:57:44 That's also why we can run a marathon.

01:57:47 A monkey could never do it,

01:57:50 but we'd still lose in a strength competition.

01:57:53 Laughter is contagious.

01:57:55 It's not just a metaphor.

01:57:57 Researchers have found that strong emotions

01:58:00 can synchronize the brain activity of different people.

01:58:03 Laughter is a phenomenon that science generally associates

01:58:06 with social creatures.

01:58:08 People have nearly 30 times more chances to laugh

01:58:11 when they are in social situations,

01:58:13 with their friends or people they feel good with.

01:58:16 A scientific theory states that we want to join people who laugh,

01:58:20 because humans are empathetic beings.

01:58:23 Your brain releases endorphins when you laugh.

01:58:26 These are special chemical substances

01:58:28 that make you feel safe and comfortable.

01:58:30 We don't know exactly why our laughter is contagious,

01:58:33 but we feel really good.

01:58:35 So...

01:58:36 In the meantime, join us on the fun side of life

01:58:43 and laugh as hard as you can.

01:58:45 [BLANK_AUDIO]

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