Que se passe-t-il après une morsure de serpent + 100 faits intéressants sur le corps humain

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Transcript

00:00:00 Oh oh, it's a bad day.

00:00:03 These two red dots on your ankle are not reassuring, it looks like you were bitten

00:00:07 by a snake.

00:00:08 You don't know if it was venomous or not, so here's what could happen next.

00:00:11 If it wasn't venomous, you can consider yourself lucky, you'll probably get by.

00:00:17 However, the neck of any snake carries thousands of bacteria, and when they enter

00:00:22 the skin, these little parasites enter your blood and wreak havoc on your body.

00:00:26 The most terrifying of them all are tetanus, a serious and incurable disease if you don't

00:00:30 get medical help very quickly.

00:00:32 Worse still, you could be one of those unfortunate people allergic to snake saliva.

00:00:37 Like in the case of bees or beetles, when the enzymes in the saliva mix with your

00:00:41 blood, your body starts trying to get rid of it.

00:00:43 It doesn't realize that it's actually fighting against itself.

00:00:46 So the conflict intensifies quickly, and you start to feel nauseous and weak.

00:00:50 Finally, it becomes difficult to breathe, and you can even faint.

00:00:54 So even if you've been bitten by a non-venomous snake, don't wait until you get medical help.

00:00:58 Then there's the worst scenario.

00:01:01 The snake was actually venomous.

00:01:03 Each snake species has its own kind of venom that acts differently from the others.

00:01:07 Let's see.

00:01:08 Ah, it can affect the heart and nerves, muscles, or blood vessels.

00:01:12 It always starts with a sharp pain at the bite spot.

00:01:15 The snake has opened its big mouth, pierced your flesh with its two upper hooks, and

00:01:20 injected its venom through the channels inside this.

00:01:23 The venom goes directly into your bloodstream, and that's where the real black magic starts

00:01:28 to work.

00:01:29 If the bite marks are clearly visible on the skin, and there's nothing else,

00:01:34 it may be a good sign.

00:01:36 If the bite starts to swell, it's probably a cobra.

00:01:39 You'll start to feel dizziness, heat swallows, and sweat.

00:01:42 But it's not yet venom.

00:01:44 It's your own reaction.

00:01:46 You're afraid at the sight of these bite marks, and the hormones of adrenaline and cortisol

00:01:50 rush from your surinal glands to your bloodstream, making you blush and shiver.

00:01:54 Your heart beats faster now, which unfortunately helps the venom spread more quickly.

00:01:59 Soon, you start to feel stomach aches and cramps.

00:02:02 The toxic enzymes contained in the snake venom react with your blood and reach

00:02:06 the internal organs and muscles.

00:02:08 As they are all close to each other, the toxic substance reaches them quickly

00:02:12 and aggressively.

00:02:13 And when the venom has crossed your liver, kidneys, and your heart, which takes about

00:02:17 15 minutes, it spreads to the nerve endings.

00:02:20 That's when you start to lose touch with reality.

00:02:25 At first, your eyelids become heavier and heavier.

00:02:27 The muscles of the eyelids are among the smallest in the body and have few nerves, which makes them

00:02:32 an easy target for the venom.

00:02:34 Then, toxins keep circulating in your blood, swallowing your small blood vessels like

00:02:38 a sponge.

00:02:39 In doing so, the nerves stop working from head to toe because they are

00:02:43 controlled by the brain.

00:02:45 It's getting worse and worse, isn't it?

00:02:47 From your eyes, the swallowing spreads to your face.

00:02:50 Your lips and cheeks are stretched, giving you the impression of being counteracted by something.

00:02:54 In an hour or two, you will lose the ability to speak and see.

00:02:58 The nerves of your face will have completely stopped working.

00:03:01 But the effects of the bite will go further, short-circuiting your tongue, your lower jaw,

00:03:05 your neck, your diaphragm.

00:03:07 When this happens, unfortunately, it's almost hopeless.

00:03:10 If the diaphragm no longer responds, your lungs can no longer function properly, and

00:03:15 you will stop breathing.

00:03:17 And that's not a good sign.

00:03:20 But if you are lucky enough, the bite could be light, and then the swallowing

00:03:24 will not affect your vital parts.

00:03:25 It will still spread from the head down to your body, but it will not be able to penetrate

00:03:30 deeply inside, passing through your upper layers, so to speak.

00:03:34 You could lose the sensitivity of your fingers and toes, of your skin, and even be

00:03:39 unable to move properly.

00:03:41 But if you can still see and breathe, the symptoms could disappear in a few days.

00:03:47 But don't bet on it either, and call an ambulance as soon as you realize that something

00:03:51 is wrong.

00:03:52 Finally, all this may be completely out of the question for you, because what you feel

00:03:56 is not a swallowing, but a heartache.

00:03:58 Cobras and elapidae both have a type of venom that goes directly into your heart.

00:04:03 When it gets there, and it's fast, it can beat more quickly or slowly the main muscle

00:04:07 of your body and cause irregular beats.

00:04:10 It's a huge constraint for your heart, so you know what to do.

00:04:13 Other muscles can also be affected, in particular by the venom of a sea snake.

00:04:19 The latter contains special toxins that target the muscles, and when your eyes become heavy,

00:04:23 you can also feel cramps, first in your stomach, then they spread quickly

00:04:27 to your arms, legs and chest.

00:04:29 You will have trouble moving because your muscles will shrink, and touching anything

00:04:33 will become a real ordeal because of your sensitivity.

00:04:36 Finally, the venom will force you to stay in bed and wait for it to disappear.

00:04:40 Finally, if it disappears.

00:04:42 Now, if you look at the bite mark and you see it inflate, and there is blood

00:04:47 coming from the two stings, it means you have been bitten by a viper.

00:04:50 This venom acts differently and is even more terrifying.

00:04:54 These molecules are bigger and cannot spread as quickly in the blood.

00:04:58 That's why they go to your lymphatic ganglions and act from there.

00:05:02 Therefore, the venom is slow and painful.

00:05:05 At first, you will only feel fear and dizziness because of this.

00:05:09 Then, after 15 minutes, the venom will begin to spread in your body from the place

00:05:14 where the viper bit you.

00:05:15 The thick and viscous substance will mix with your blood, making it coagulate and causing

00:05:20 eczema.

00:05:21 The higher it goes, the more it affects your body, but this progression is slow compared

00:05:24 to the effects of cobra bites and stoning.

00:05:26 If you do not get medical assistance, you will notice that the swelling increases

00:05:31 from hour to hour.

00:05:33 When the venom is scurrying through your lymph, it turns it against you, causing

00:05:37 an even greater swelling.

00:05:38 The lymph is the main barrier of defense of your body.

00:05:42 It is a liquid that contains white blood cells that fight diseases.

00:05:45 The venom gets in their ranks and causes disorders.

00:05:48 The white blood cells attack it in vain, and they spread further and further.

00:05:52 And when this vile thing reaches the lymphatic ganglions, it swells, desperately trying

00:05:56 to get rid of the intruder.

00:05:58 The production of lymph increases, and the bitten part of your body becomes more and more

00:06:02 swollen.

00:06:03 Depending on the power and quantity of venom, your limb will double in volume in two or

00:06:07 three days from the bite.

00:06:09 And since we mentioned the ankle, it's all your leg that will be affected, from the foot

00:06:14 to the hip.

00:06:15 You will not be able to walk, of course, and the sitting position will also be unimaginable.

00:06:19 The only hope at this stage is to lie down in your bed and try not to move, even

00:06:23 so late.

00:06:24 There is still a chance that your body will heal itself.

00:06:27 But if there is a possibility of taking you to the hospital, do not hesitate a second.

00:06:31 If you are bitten by a snake, you risk panicking and doing everything wrong.

00:06:36 So increase your chances of survival by calming down.

00:06:39 Fear will make your heart beat faster by pumping blood into your body, and with it

00:06:43 the venom.

00:06:44 It takes time to reach your circulation, so stay calm and lie down while keeping the

00:06:49 bitten limb under your heart.

00:06:51 Gravity will then do the work.

00:06:53 Never try to suck the venom of the wound.

00:06:55 It spreads too quickly for you to do it.

00:06:58 You won't even be able to extract some of it that way, and you'll just have to increase

00:07:02 your heart rate by exhaling.

00:07:03 Put this knife away, and never try to cut the bite to get the venom out.

00:07:08 As mentioned, it is already in your blood, and you can aggravate the situation by cutting.

00:07:12 If there is no infection inside the wound, you could catch one because of the knife.

00:07:16 The cold application will not help either.

00:07:19 The cold restricts normal blood circulation, which means that the venom stays where it is

00:07:23 and does the most damage in one place.

00:07:25 The venom can also make tissues more vulnerable to frostbite.

00:07:28 You could end up losing a limb.

00:07:30 The same goes for tight bandages and garrows.

00:07:33 When the blood circulates freely, it lets the venom spread, of course, but it also dilutes

00:07:37 it, which makes the substance less powerful.

00:07:40 The bite may not be as dangerous as you think, but by applying a tight bandage,

00:07:45 you can triple its power.

00:07:46 Look, you did it!

00:07:48 You're out of here!

00:07:50 Oh, wait a minute!

00:07:52 Well, too bad.

00:07:53 Imagine this.

00:07:55 If someone managed to unroll all the DNA contained in the human body, it would extend

00:08:01 over about 16 billion kilometers.

00:08:03 Do the math.

00:08:05 That's twice the distance from Earth to Pluto.

00:08:07 And it's not the only incredible thing our body is capable of.

00:08:11 Trillions of nerve connections constantly feed your memory.

00:08:15 According to some studies, after watching 2,500 images for only 3 seconds, most people

00:08:21 will remember these images with an accuracy rate of 92%.

00:08:26 Incredible.

00:08:27 Your body is shining, emitting tiny amounts of barely visible light.

00:08:31 This glow is the product of biochemical reactions that have their home in your body.

00:08:36 The light increases and decreases throughout the day.

00:08:39 Although it is not visible, you cannot detect it with the naked eye.

00:08:43 Bacteria represent between 0.5 and 2.7 kilos of your total body weight.

00:08:50 And between 100 million and 1 billion bacteria can live on a single tooth.

00:08:55 It is impossible to perceive the flavor of food without saliva.

00:08:59 Indeed, the chemical substances contained in food must be dissolved in the saliva

00:09:03 before being detected by the taste buds.

00:09:06 It may sound like a myth, but eating too many carrots can actually make your skin orange.

00:09:12 Carrots contain large amounts of beta-carotene.

00:09:15 This compound can cause what is called carotenemia.

00:09:19 If you have too much of it in your blood, it sticks to the parts of your body where the skin is thickest.

00:09:24 On the soles of the feet, on the knees, elbows, palms, and even on certain areas around the nose.

00:09:30 But do not worry, it is not dangerous.

00:09:33 You can easily reverse this phenomenon by reducing your consumption of foods rich in beta-carotene.

00:09:39 The muscles of the chin, whose scientific name is "chin muscle", have a rather bizarre aspect.

00:09:45 We do not really know what to think of it.

00:09:47 Look at these strange little "tentacles".

00:09:50 Yet, they allow us all kinds of expressions, making the lips, chin and cheeks play.

00:09:55 And yes, it is they who are the origin of these wrinkles and these bizarre folds that appear on your chin.

00:10:02 And this, because these muscles pull directly on the skin.

00:10:07 We can live without some of our organs and lead a normal life.

00:10:11 The human body is composed of simple organs and working organs in pairs.

00:10:15 And when you have two, one is enough for you to survive.

00:10:19 Your gastrointestinal tract is not really that small.

00:10:22 It is even bigger than you.

00:10:24 It measures about 7 meters.

00:10:26 The cornea, the transparent part of your eyes, is not irrigated by blood.

00:10:31 It is the air that directly provides it with the oxygen it needs.

00:10:35 Humans develop their unique digital prints very early in their lives,

00:10:39 at the embryonic stage, only three months after conception.

00:10:42 Moreover, even if we seriously damage these digital prints,

00:10:46 they grow back naturally and find their original drawing.

00:10:49 The whole world is born with an immersion reflex.

00:10:52 This reflex is activated and interrupts bodily functions in the event of drowning or prolonged immersion.

00:10:58 The human brain is not smooth at all.

00:11:01 But if you decide to flatten all the ridges that cover it,

00:11:04 your brain will be the size of a pillowcase.

00:11:06 Not so useful, however.

00:11:08 Newborns blink only once or twice a minute.

00:11:12 For comparison, an adult person blinks at least 10 times during the same period of time.

00:11:18 Our lungs are the only organs capable of floating on water.

00:11:21 The reason is that they are made up of about 300 million alveoli,

00:11:24 small structures in the form of balloons.

00:11:26 Moreover, even if we are in perfect health,

00:11:29 our lungs are never totally free of germs or sterile.

00:11:32 Your nose is a superhero.

00:11:34 It is both a heating, a filter and a humidifier.

00:11:38 All this thanks to its "horned" body, three pairs of bone-wound blades.

00:11:42 They contain blood vessels capable of heating the air

00:11:45 and caliciform cells used to humidify it.

00:11:48 In addition, the air you breathe is filtered by your nose

00:11:51 before being sent to your lungs.

00:11:54 Every time you eat something, your esophageal system,

00:11:57 the organ through which food passes to reach your stomach,

00:12:00 performs a series of undulating contractions that push food.

00:12:04 This is what is called peristaltism.

00:12:07 There is a link between your digestive system and your brain,

00:12:10 the brain-intestinal axis.

00:12:12 This is why stress or brain problems can affect the way your body digests food.

00:12:17 Even if hockey is generally harmless and stops by itself after a few minutes,

00:12:22 it is not really pleasant.

00:12:24 You should know that it can occur as a result of a temperature change.

00:12:29 The density of your brain increases throughout your life.

00:12:32 All this because new neural connections appear.

00:12:35 They also appear because the structure of the brain never stops changing.

00:12:39 If you do not want to go into eternity, pinch the skin of the ridge of your nose.

00:12:44 Your brain then receives an alarm signal.

00:12:47 Very quickly, it slows down all other processes,

00:12:50 including the reflex to go into eternity.

00:12:52 In fact, studies have shown that going into eternity is a way for your nose to "reinitialize".

00:12:58 Eternity "reinitializes" cells called "cells" that cover your nasal cavity.

00:13:03 The part of the brain responsible for vision is located at the back of the head.

00:13:08 It is interesting to note that the right side of your brain controls the vision of the left side, and vice versa.

00:13:14 If you are in a noisy place, in a nightclub or at a concert,

00:13:19 cover your ears and you will hear your friends better.

00:13:22 Push on the tragus, the rounded, covered ridge of skin,

00:13:25 which is located just in front of the auditory tract, so that it penetrates your ear.

00:13:29 Then turn this ear to your friend.

00:13:31 When a person snores, the noise usually does not exceed 60 decibels.

00:13:36 It's about the volume of a normal conversation.

00:13:39 But the sound level can sometimes reach 80 decibels.

00:13:42 It is the noise that a mixer makes while cooking.

00:13:45 Like salamanders that push their tails back,

00:13:48 we would be able to regenerate our cartilage,

00:13:51 the rubbery material that envelops our joints.

00:13:54 Scientists have recently discovered that the cartilage could repair itself.

00:13:58 This process is apparently effective at the ankle,

00:14:01 less effective at the knee and even less effective at the hip.

00:14:05 If a person suffers from anosmia, also called olfactory cystitis,

00:14:10 it can neither detect nor distinguish odors.

00:14:13 Your eyes do not stop moving when you look at something.

00:14:17 Without that, you could not see the whole picture.

00:14:20 This movement escapes you because your brain is an excellent video editor.

00:14:24 It stabilizes the images and all these fragments in a homogeneous visual flow.

00:14:29 The liver is the only human organ capable of regenerating completely.

00:14:34 Even if it must regenerate up to 25% of its initial weight,

00:14:38 the organ will find its original size.

00:14:41 Your mouth itches when you gnaw on pineapple,

00:14:44 because while you eat this fruit, it eats you too, well, in a way.

00:14:49 Pineapple would be the only food to contain bromelain.

00:14:52 It is an enzyme that breaks down proteins.

00:14:55 Fortunately, our gastric acid knows how to deal with this ugly enzyme.

00:14:59 Bacteria capable of producing electricity live in our intestines.

00:15:04 These bacteria emit electrons,

00:15:06 which creates tiny electric currents.

00:15:09 This may be the way bacteria produce energy.

00:15:12 The impression of déjà vu could actually result from a shift

00:15:16 in the processing of information by the brain.

00:15:19 This shift would occur when our brain transfers information between different areas.

00:15:25 If there is any delay, your brain will receive the same information twice.

00:15:31 As a result, it will consider it as an event that has already occurred.

00:15:35 The mutation of the DECTU gene allows some people to sleep only a few hours

00:15:40 while feeling in good shape.

00:15:42 They are not tired and never do the morning fat.

00:15:45 On average, these people wake up at 4 or 5 in the morning.

00:15:49 5% of the world's population has this feature.

00:15:53 It happens that your ears are bleeding or hurt when you travel by plane.

00:15:58 You can solve this problem by chewing a chewing gum.

00:16:01 This opens the stache tube,

00:16:03 a narrow duct that connects your throat to your middle ear.

00:16:06 The opening of this duct balances the pressure inside the ear

00:16:10 and puts an end to this unpleasant phenomenon.

00:16:13 Chewing also opens the stache tube.

00:16:16 It is possible that your feet get bigger with age,

00:16:19 just like your nose and ears.

00:16:21 As we age, our feet weaken at the level of ligaments and tendons.

00:16:25 The plantar vault flattens.

00:16:27 The feet become wider and longer.

00:16:30 Look at this.

00:16:33 There are people who can fold their little finger without folding their ring finger.

00:16:37 But most find it difficult, or even impossible to accomplish.

00:16:41 When they move their middle finger or little finger,

00:16:44 they tend to slightly bend their ring finger as well.

00:16:47 Yes, for me too.

00:16:49 The luxation of the ocular globe is an extremely rare condition

00:16:53 that allows some people to bring their eyes out of their orbits.

00:16:57 Unfortunately, this ability has disadvantages.

00:17:00 It can lead to many eye problems.

00:17:03 Some indigenous peoples, like the Tibetans,

00:17:06 can survive at altitudes as high as Mount Everest.

00:17:10 This rare ability probably appeared after years of evolution.

00:17:15 The ancestors of the modern Tibetans lived in high regions for thousands of years.

00:17:20 And their red blood cells adapted to this condition,

00:17:23 making it possible to survive at dangerously low oxygen levels.

00:17:27 The Bajau are nomads from the sea living in Southeast Asia.

00:17:31 These individuals have developed an extra large rat

00:17:34 used to store blood cells rich in oxygen.

00:17:37 Thanks to this, they can easily spend 5 to 10 minutes

00:17:41 fishing underwater without going back to the surface to breathe,

00:17:44 if only once.

00:17:46 About 14% of the population is deprived of long-palm muscle.

00:17:51 Poor old man.

00:17:52 It is actually a rudimentary part of the body,

00:17:55 and the need for it has disappeared during our evolution process.

00:17:59 So, if you don't have this muscle, don't worry.

00:18:03 Its absence does not affect the functioning of your forearm in any way.

00:18:07 About 5 to 37% of people have been deprived of wisdom teeth since their birth.

00:18:13 These teeth are no longer really necessary today.

00:18:16 They were important for our ancestors,

00:18:19 because they helped them to chew hard foods like nuts,

00:18:22 roots and raw meat.

00:18:24 And the caramels, sweet and salty, from Guérande.

00:18:27 No, I'm making it up.

00:18:29 But since most of the food we eat today is transformed,

00:18:33 wisdom teeth are no longer just a simple atavism.

00:18:36 Most people have only one spiral of hair implantation

00:18:40 that goes in the direction of needles and a watch.

00:18:42 But 5 people out of 100 have a double crown.

00:18:46 And if the two spirals are directed in the opposite direction of needles and a watch,

00:18:50 it makes the person even more unique.

00:18:53 Some scientists think there is a genetic link

00:18:56 between the direction of this spiral and our right hand.

00:18:59 A little more than 8% of right-handed people have a spiral

00:19:03 going in the opposite direction of needles and a watch.

00:19:06 But in left-handed people, this number goes up to 45%.

00:19:10 The brain of the man ages faster than that of the woman.

00:19:14 As they get older, men begin to complain more and more often

00:19:17 of memory problems and lack of concentration.

00:19:20 At the same time, women do not have such serious problems with their memory,

00:19:25 but they feel more often depressed.

00:19:27 Which one would you choose?

00:19:29 When a person lies, his own nose betrays him.

00:19:32 Psychologists at the University of Grenada have discovered

00:19:35 that when a person told a lie,

00:19:37 the temperature around his nose and in the inner corners of his eyes increased.

00:19:42 This phenomenon was called, surprise surprise,

00:19:45 Lef-Epinocchio.

00:19:47 Japanese people have specific bacteria,

00:19:49 the plebeian bacteroides, in their intestines.

00:19:53 These bacteria help them digest sushi.

00:19:55 The Japanese have been eating raw algae for centuries.

00:19:59 The microorganisms present on the surface of these algae

00:20:02 have entered their bodies and have actively developed.

00:20:05 Today, these bacteria help the Japanese digest raw food

00:20:09 and prevent various problems related to their diet.

00:20:13 Humans would have as many hairs on their bodies as chimpanzees.

00:20:16 The number of hairs of an individual and a chimpanzee is approximately the same.

00:20:21 The only difference is that the human body hair is essentially useless

00:20:25 and so thin that it is almost impossible to distinguish.

00:20:28 Humans do not have more genes than other species.

00:20:31 In fact, people have even less genes than a fly.

00:20:34 Tomatoes also have a lot more genes than you and me.

00:20:37 But we are creatures so complex.

00:20:40 Well, recently, scientists have concluded that the number of genes contained in a genome

00:20:45 was not closely related to the complexity of a living being.

00:20:49 Let's take a break to breathe a little.

00:20:52 And speaking of that, your left lung is made up of two lobes,

00:20:55 while your right lung is divided into three parts.

00:20:58 In addition, the left lung is a little smaller,

00:21:01 because it must leave room for your heart.

00:21:04 Your lungs also contain about 2,400 km of respiratory vein.

00:21:09 It is more than half the distance between New York and Los Angeles.

00:21:13 There are also more than 300 million alveoli in your lungs,

00:21:17 which are small air bags in the shape of balloons.

00:21:20 People have five senses, among the most obvious.

00:21:23 Sight, smell, touch, hearing and taste.

00:21:27 But that's not all.

00:21:28 What about thermosensation, the sense of heat?

00:21:31 Or nociception, the perception of pain?

00:21:35 Or even awareness of one's own body, proprioception?

00:21:39 To understand what it is about, close your eyes and touch your nose.

00:21:43 Did you succeed?

00:21:45 It's thanks to proprioception.

00:21:48 This list can be much longer.

00:21:50 Some experts say that people have 21 to 53 senses.

00:21:56 Your fingers become all frizzy after spending too much time in the water.

00:22:00 The frizzy fingers are caused by the shrinking of your blood vessels.

00:22:04 When you stay in the water for a long time,

00:22:06 your nervous system makes your capillaries retract.

00:22:09 Your body removes the blood from this area.

00:22:12 And this loss of blood makes your vessels narrower.

00:22:15 The skin begins to fold around them, forming these funny wrinkles.

00:22:19 Scientists think this process would help us to have a better grip

00:22:23 when our hands and feet are wet.

00:22:26 There are three kinds of cones in the eyes of an ordinary person.

00:22:29 These cones help to recognize colors in blue, red and green spectrums.

00:22:35 Thanks to them, most people can distinguish about a million different shades.

00:22:41 Those who are gifted in tetrachromatism have four cones in their eyes.

00:22:45 This feature allows them to see up to 100 million different shades.

00:22:49 This anomaly of vision is extremely rare.

00:22:52 And it is much more common in women than in men.

00:22:55 Interestingly, most people with tetrachromatism

00:22:59 do not even realize that they see a brighter world than others.

00:23:03 Not all people have round pupils.

00:23:06 Two out of 10,000 people have unusual-shaped pupils.

00:23:10 Most often, they have a kind of lock.

00:23:13 This eye disorder is called colobom.

00:23:16 It should be noted that some people with this condition have no vision problems.

00:23:22 Only 3 to 22% of people in the world have a morton's toe or Greek foot.

00:23:28 It is a structure of the foot where the second toe is longer than the first.

00:23:32 Michelangelo's David and the Statue of Liberty

00:23:35 both have this unusual body feature.

00:23:39 For my part, I prefer to have them in a fan.

00:23:42 In some people, saliva accumulates in a gland under their tongue.

00:23:47 It can then be propelled by a jet when the person presses on this gland.

00:23:51 If the mouth is open at that moment, the jet can reach several meters.

00:23:56 This process, the "glavitur" effect, can occur spontaneously.

00:24:01 A person accidentally presses his tongue against the gland by eating,

00:24:04 drooling, speaking or brushing his teeth.

00:24:09 Up to 35% of people could have this, but only 1% can do it on command.

00:24:15 I had a friend at the university who did this.

00:24:18 Yes, it was weird.

00:24:20 About 18 to 35% of people have an interesting reaction to sunlight.

00:24:25 They "ethernuate".

00:24:27 This phenomenon has its own name, the photosternitatory reflex.

00:24:31 In Greek, it means "sunny ethernation".

00:24:35 Just like salamanders make their tails grow back,

00:24:37 humans could be able to regenerate their cartilage.

00:24:41 It is this rubbery material around your joints.

00:24:45 Recently, scientists have discovered that the cartilage could be able to repair itself.

00:24:51 In the most effective way, on the ankle,

00:24:53 not very well on the knees and less effectively on the hip.

00:24:57 The human brain is composed of 73% of water, just like your heart.

00:25:01 That's why if your brain loses only 2% of liquid,

00:25:05 you start to feel exhausted.

00:25:08 This also affects your memory,

00:25:10 reduces your attention capacity and has a negative impact on your mood.

00:25:14 So, drink a shot.

00:25:17 Your brain constantly processes tons of visual information,

00:25:20 about 600 million bits per minute.

00:25:23 Everything starts when light crosses the cornea.

00:25:26 The protective outer layer is transparent to your eye.

00:25:30 Then, light turns into electric signals.

00:25:33 They move towards your brain and interpret them in images you see.

00:25:38 This complex process takes place in a few milliseconds.

00:25:42 People who live up to 110 years and more,

00:25:45 known as "super centenarians", could have a secret.

00:25:49 Researchers have discovered that their immune cells are called

00:25:53 "T-Auxiliary lymphocytes".

00:25:56 They could change and adapt to the last stage of aging.

00:26:00 These cells are likely to protect them from viruses and other health problems.

00:26:05 We have become multitasking workers thanks to technology.

00:26:09 Or rather, it seems to be the case.

00:26:12 The human brain cannot concentrate on two things at the same time.

00:26:15 What it can do is to quickly switch from one task to another.

00:26:19 But this reduces your attention span and short-term memory loss,

00:26:23 as well as your learning capacity.

00:26:26 So, put this phone down.

00:26:29 You may have this physical feature without knowing it,

00:26:34 because sometimes even radiographs miss it.

00:26:37 We have, for the most part, 12 pairs of ribs,

00:26:40 that is, 24 ribs in all.

00:26:43 However, some people have 25.

00:26:46 One in 200 people is born with this little "plus".

00:26:50 It is the cervical spine syndrome.

00:26:53 This rib, in addition, is generally located above the first ribs,

00:26:56 at the base of the neck and just above the clavicles.

00:26:59 It's nothing alarming.

00:27:01 Most of the time, the cervical ribs go unnoticed,

00:27:04 and if they ever cause pain, they are easy to remove.

00:27:07 Do you see the huskies?

00:27:09 Have you noticed that their eyes are sometimes two different colors?

00:27:12 Some humans also have this feature.

00:27:15 It is a phenomenon called heterochromia.

00:27:18 This word comes from the ancient Greek "heteros", which means "different",

00:27:22 and "chroma", which means "color".

00:27:25 There are cases of total, central or partial heterochromia.

00:27:30 When the eyes of the person are two completely different colors,

00:27:34 let's say a brown eye and a green eye,

00:27:37 we talk about total heterochromia.

00:27:39 When the outline of the pupil is a different color

00:27:42 than the iris, we talk about central heterochromia.

00:27:45 And when one part of the eye is a different color,

00:27:48 we talk about partial heterochromia.

00:27:50 You are born with this feature, but it can also occur at a specific time,

00:27:54 such as after an accident.

00:27:56 It is still very rare.

00:27:58 In the United States, people with this feature are less than 200,000.

00:28:01 Let's say it's pretty cool anyway.

00:28:04 Speaking of eye color, do you know what the rarest color is?

00:28:09 No need to google it, it's grey.

00:28:12 You might think it's blue, and you're not entirely wrong.

00:28:16 The percentage of people with blue eyes is estimated to be between 8 and 17% worldwide.

00:28:22 As for grey eyes, they are even less common.

00:28:25 Less than 1% of the population has eyes of this color.

00:28:29 This very rare feature is due to a low level of melanin in the layers of the iris.

00:28:34 You are more likely to meet someone with grey eyes in Eastern and Northern Europe.

00:28:39 There are even rarer "god" colors, like red and purple,

00:28:43 but it can simply be a symptom of a particular state of health.

00:28:47 There are people who are likely to distinguish 100 million different colors,

00:28:52 and without the help of gadgets.

00:28:55 We distinguish colors thanks to photoreceptors located in our eyes.

00:28:59 We generally have three types of photoreceptors,

00:29:03 capable of translating what we see in color that our brain can capture.

00:29:07 Researchers think there is a small group of people called tetrachromats,

00:29:12 and they have four types of photoreceptors.

00:29:15 To date, researchers have identified only women with this feature.

00:29:20 Do you see this little piece of flesh hanging at the bottom of your throat?

00:29:24 Yes, the one that helps you swallow. It's a lute, also called a "uvule".

00:29:29 This name comes from Latin "uvula", which means "little grain of grapes".

00:29:33 Some people are born with what is called a "bifid lute",

00:29:37 that is, a lute presenting a slit or fork.

00:29:41 It's great for a party.

00:29:44 Joking aside, people with bifid lutes may have problems eating, drinking and talking.

00:29:52 They may also have digestion problems and have a strange speech.

00:29:57 But it depends on the size of the slit of the lute.

00:30:01 Here is a feature that is not ideal for enjoying your holidays,

00:30:05 but people who are provided with it are more effective with less hours of sleep.

00:30:09 It is said that Nikola Tesla, Margaret Thatcher and Winston Churchill

00:30:13 presented this super rare feature.

00:30:16 This gene, called DEC2, helps regulate circadian rhythms.

00:30:22 These are our natural biological clocks,

00:30:25 which tell us when to go to sleep and eat,

00:30:28 making us feel tired or hungry.

00:30:31 A person with this rare mutation has a shorter sleep cycle than the average.

00:30:36 She will feel rested even after having slept only 4 or 5 hours.

00:30:41 I would love to have the same superpower!

00:30:44 What would you say about a genetic mutation that allows you to have superhero bones?

00:30:50 The bones become virtually unbreakable and the skin is less prone to aging.

00:30:55 It really looks like with this mutation you can get out of any accident and resist as long as it goes.

00:31:01 Some people have a very attractive feature,

00:31:05 which can go unnoticed at first glance.

00:31:08 It presents what is called dystichiasis, a second row of eyelashes.

00:31:14 If you ever wanted to know more about the medical aspect of this feature,

00:31:18 it is the result of a genetic mutation of the FOXC2 gene.

00:31:22 It may be very pretty to see,

00:31:24 but people affected by dystichiasis may feel a gene in the eyes.

00:31:29 And in some cases, they may have vision problems.

00:31:33 You may never have heard of the hair loss syndrome, but you may have it.

00:31:40 I know, the name says it all, but just for your information, it makes your hair dry and messy.

00:31:47 They become so unmanageable that you can't comb them.

00:31:51 They also tend to grow in all directions.

00:31:55 As for the color, hair is generally light blue or silver.

00:31:59 We generally have cylindrical hair.

00:32:03 People affected by this syndrome have triangular hair, heart-shaped or simply flat.

00:32:09 It is an extremely rare syndrome.

00:32:11 There are only 100 confirmed cases, and it fades with age.

00:32:16 Most humans have evolved by developing traits depending on the geographic area where they live.

00:32:22 But there are some individuals, especially those who live at altitude,

00:32:27 who have developed rather cool traits.

00:32:30 Let me explain.

00:32:31 There is less oxygen at altitude.

00:32:34 Not only have these individuals adapted to it, but they are also very well behaved in this type of environment.

00:32:40 For example, the inhabitants of the Andes in South America have red blood cells that carry much more oxygen than the average.

00:32:48 Their circulatory system is much more efficient.

00:32:52 In other similar environments, individuals have adapted to their way.

00:32:58 They have the ability to breathe more to meet the needs of their oxygen-rich bodies.

00:33:05 Here is a trait that has an aesthetic interest, but has almost no impact on health.

00:33:11 The balding foot.

00:33:13 People with this trait have little melanocytes,

00:33:17 the cells that produce the pigments of hair in certain parts of the hair.

00:33:21 Decolorated hair is generally located at the front of the scalp.

00:33:25 It can also be eyebrows or eyelashes.

00:33:28 This is a trait that exists from birth and that persists throughout life.

00:33:34 If you want to get rid of it, you can always dye your hair, but personally, I think it looks super cool.

00:33:40 We all know that coriander doesn't like everyone.

00:33:44 I don't know what you think, but for me it tastes like soap.

00:33:47 It's not really a matter of taste, but rather of genetics.

00:33:51 A study conducted on 30,000 individuals showed that people who consider that coriander tastes like soap have a particular gene

00:33:59 that reacts more to the smell than to the taste of the plant itself.

00:34:03 If you are one of these people, but you want to give coriander a chance,

00:34:07 you can try this little trick or ask the people who cook at your house to do it.

00:34:13 Fold the leaves before using them.

00:34:16 Why?

00:34:18 Because by crushing the leaves, the components responsible for this taste of soap decompose and thus disturb much less.

00:34:25 Unlike our other primate cousins, most people have plantar vaults.

00:34:31 They help us move.

00:34:33 This plantar vault acts as an integrated shock absorber for our feet.

00:34:36 It's what makes us bounce.

00:34:38 But there is another one.

00:34:40 It's the transversal arched lull that extends from one side to the other on top of the foot.

00:34:45 You can see it as a bridge that would help keep your foot in its form.

00:34:49 Research shows that this arch is also important, because it is responsible for about 40% of the stiffness of the foot.

00:34:56 In other words, it is the scaffolding that keeps the foot in place.

00:35:00 When medical researchers dissected this transversal arch, the foot lost a lot of its firmness.

00:35:06 However, when they incised the lower part of the lull, the loss was not as spectacular.

00:35:12 Is this a phenomenon typical of modern man?

00:35:15 No, these arches do not date from yesterday.

00:35:17 The transversal arch has existed for nearly 3 million years.

00:35:20 And the medial arch appeared about 1.8 million years ago.

00:35:24 We might as well dwell on another element of our feet before moving on to other parts.

00:35:28 The little toe is, too, more important than it seems.

00:35:32 Whether you were born without it or you lost it by accident, you can still walk.

00:35:37 But these little fingers are important to keep us standing.

00:35:41 They ensure balance.

00:35:43 Inside your foot are 26 bones that join together to prevent you from tilting.

00:35:48 The little toe is part of this balance work.

00:35:51 Our ancestors, the great apes, needed their toes to climb,

00:35:55 climb and swing on trees.

00:35:58 Today, we have traded our climbing skills for comfortable sofas and TV series.

00:36:04 Well, let's look a little higher and talk about the appendix.

00:36:08 You might think it's useless. But no.

00:36:11 When a human being is in his mother's womb, this organ is already starting to work.

00:36:15 Around the 11th week of development, it begins to produce special cells

00:36:20 that release useful hormones and compounds.

00:36:22 The appendix helps train the immune system's troops,

00:36:26 making sure they form a first-order defense.

00:36:29 It also collects all kinds of foreign substances, called antigens,

00:36:34 coming from our digestive tract.

00:36:36 However, as food regimes evolve,

00:36:40 this piece shrinks like a deflating boulder.

00:36:43 Unlike most other vestigial structures, the appendix is not always harmless.

00:36:48 It can turn into a real calvary.

00:36:51 By the way, the vestigial organs are the ones that have lost their main ancestral function.

00:36:56 Most of the time, these structures are no longer of apparent use.

00:37:00 Another famous vestigial example is that of wisdom teeth.

00:37:04 They are useless and have been causing us problems for centuries.

00:37:07 Yet, 95% of us have them.

00:37:10 And 90% of us might even be confronted with the discomfort of wisdom teeth.

00:37:17 If you don't have any, you can consider yourself lucky.

00:37:20 And here's another interesting fact about wisdom teeth.

00:37:23 Even if your teeth are covered in a mineral that is more tender than shark teeth,

00:37:27 new tests show that they are just as resistant.

00:37:31 Shark teeth are actually coated with a hardness similar to that of human wisdom teeth.

00:37:37 This is explained by the fact that their surfaces are made up of mineral crystals

00:37:41 held together by proteins.

00:37:43 These prevent them from breaking easily in the event of an impact.

00:37:47 The difference between the use we make of our teeth and that of sharks

00:37:51 is therefore their design, and not their hardness.

00:37:54 Anthropologists have examined ancient skeletons.

00:37:57 They believe that our ancestors needed these additional teeth

00:38:00 to chew on hard foods, such as roots and raw meat.

00:38:04 At the time, these additional teeth were very useful.

00:38:08 But we discovered cooking and, suddenly,

00:38:11 our food became more tender and our jaws more reduced.

00:38:15 Geneticists have their own point of view on the matter.

00:38:18 This is a gene called MIH16,

00:38:21 which seems to play a role both in the size of the brain

00:38:24 and in the characteristics of the jaw.

00:38:26 However, the exact role it played in the history of our evolution

00:38:30 remains a bit mysterious.

00:38:32 Now, another useless thing is our eyelid.

00:38:35 Finally, not the normal eyelid.

00:38:37 We are talking about this little pink thing that hides at the corner of the eye.

00:38:40 Birds and other fur-covered animals use it to push back dust and debris

00:38:45 that could damage their eyes.

00:38:47 But in humans, it is largely vestigial.

00:38:50 Here is the long-palmar muscle.

00:38:53 About 85% of us still wear it,

00:38:56 and maybe you have it too.

00:38:58 You can test it by placing your hand on a flat surface

00:39:01 and by touching your ear and thumb.

00:39:04 If you notice a small group of tendons that make pirouettes in the middle of your wrist,

00:39:08 you know you found it.

00:39:10 It was used to grab objects and swing like Tarzan.

00:39:13 Let's continue with the tip of apprehension.

00:39:16 Even before being born, around the 16th week of your stay in your mother's womb,

00:39:20 you are already starting to catch a cold.

00:39:22 You start by grasping your umbilical cord.

00:39:24 When you finally arrive in the world, this reflex helps you hang on.

00:39:28 Funny fact.

00:39:30 Little monkeys can hang on one hand during the lustre

00:39:33 thanks to a similar trick.

00:39:35 On the other hand, we, humans, lose this over-preparation around the age of 3 months.

00:39:41 When you are still in gestation, you also have a mini-tail.

00:39:44 But as you grow up, it disappears

00:39:47 and these tiny vertebrae become your coccyx.

00:39:50 Humans and our cousins, the big monkeys, don't have tails, unlike other animals.

00:39:55 Our ears also have vestigial muscles.

00:39:57 They allow animals to hear better and express certain feelings.

00:40:01 But in humans, these ear muscles are not very useful.

00:40:05 We have found other ways to listen and show our emotions.

00:40:09 However, some of us can still move their ears with a little training.

00:40:14 It is surprising to note that the nails of the toes are also part of the vestigial elements.

00:40:19 They are the first line of defense, because they protect the body against harmful microorganisms.

00:40:25 During our evolution, we have used the nails of our hands and feet to defend ourselves, dig and climb.

00:40:32 In the modern world, nails still come in handy,

00:40:35 whether to peel a fruit or for the sweet sensation of scratching a snack.

00:40:40 On the other hand, the nails of the feet have retired.

00:40:43 But hey!

00:40:45 We can still apply nail varnish to them.

00:40:47 For the love of style, they are certainly suitable for many people.

00:40:51 Humans are not the only ones to have limbs or useless organs.

00:40:55 In 1798, an anatomist examined a single bird unable to fly and gave his observations.

00:41:03 This avian species was none other than the ostrich.

00:41:06 Ostriches and cassowaries are just a few examples of birds with vestigial wings.

00:41:12 From an anatomical point of view, they are rudimentary wings, unable to allow these corpulent creatures to fly.

00:41:19 However, they are not totally devoid of function.

00:41:23 They serve to maintain balance during fast races.

00:41:26 In addition, they allow to develop nuptial parades, helping these birds to attract potential partners.

00:41:33 Now, when it comes to animals, many of them shine too.

00:41:37 About 76% of marine animals, including jellyfish, greens, sharks and starfish, are bioluminescent.

00:41:45 They have a molecule called luciferin, which reacts with oxygen to create light.

00:41:51 For them, this glow is used to confuse predators, attract prey or warn others of a danger.

00:41:57 We humans can also shine.

00:41:59 Unfortunately, this glow is very weak and our eyes cannot see it.

00:42:04 Our body emits light, but it is about a thousand times weaker than what our eyes can detect.

00:42:10 Scientists have discovered that this glow changes throughout the day.

00:42:14 It is the weakest in the morning and the brightest in the late afternoon.

00:42:18 Our face shines more than the rest of our body.

00:42:21 It is thought that this is due to the fact that our face is more exposed to the sun and that it contains melanin,

00:42:27 whose components can stimulate the production of light.

00:42:30 Some unique faculties distinguish us from the rest of the animal kingdom.

00:42:34 Did you know, for example, that man was the only animal capable of blushing?

00:42:38 It would seem that we have the exclusivity of this phenomenon on sunny days.

00:42:43 When we find ourselves in an embarrassing situation, our blood vessels dilate and that is what makes us blush.

00:42:49 Embarrassment is a rather complex emotion.

00:42:52 It is about understanding what others think of us, and it may be too complex for other animals.

00:42:58 It is interesting to note that bald Wacaris are also monkeys capable of blushing, but without giving it the same meaning.

00:43:05 For them, it is a proof of good health.

00:43:08 Speaking of good health, we must pay tribute to our bowels.

00:43:12 These include the stomach, the liver and many other things.

00:43:16 They are often called our "second brain".

00:43:19 The latter has its own nervous system, strong enough to send a hundred million messengers to the rest of your body.

00:43:26 Even if the connection between the brain and the stomach is cut off, it continues to operate.

00:43:31 They ensure the autonomous functioning of your digestive system.

00:43:36 Here is a young man in costume. He has a secret.

00:43:41 He is in the bathroom, standing in front of his mirror, and he washes his face in cold water to give himself courage.

00:43:47 There is no one else here but him, but he is not alone.

00:43:50 Our friend looks nervous.

00:43:52 He taps his cheeks, looks in the mirror and says, "Do not worry, we'll get by.

00:43:57 It's been so long since we've done this, we're going to win."

00:44:00 If he says "we", it's not because he has a double personality.

00:44:03 And no, he does not address another person through a small microphone either.

00:44:07 He says "we" because he knows something.

00:44:10 Technically speaking, he is not just a hand, he is a group of billions of living creatures.

00:44:15 He, you and all of us on Earth are not exactly what we think we are.

00:44:20 Your body is made up of human cells, only 43%.

00:44:23 The remaining 57% are microbes and bacteria.

00:44:27 This man is now going on stage to reveal this secret to us.

00:44:31 Get on the scale.

00:44:33 Do you see the figure? Subtract a little more than half of that.

00:44:36 Here is your real weight.

00:44:38 Everything else is just microscopic organisms.

00:44:40 It's hard to believe because in this case, your body should constantly change shape and disintegrate into tiny particles.

00:44:47 You will see your skin flutter and move continuously.

00:44:50 Fortunately, this does not happen for two reasons.

00:44:53 First, the microbes are tiny, their movements are not visible.

00:44:58 Secondly, most of this microbial world is in a dark place that we cannot see.

00:45:03 A place without access to oxygen, in our intestines.

00:45:06 This is where billions of little creatures walk around us.

00:45:09 Do you feel a little overwhelmed all of a sudden?

00:45:12 Some of these creatures were already there before our birth.

00:45:16 But most of them are colonists who have entered you with food and water.

00:45:20 At the surface of your body, all microbes come from the environment.

00:45:24 Every corner of your skin is covered with microbes.

00:45:27 Whatever your efforts, it is impossible to get rid of them.

00:45:31 There are more microbes than human cells.

00:45:34 Our genome is composed of about 20,000 genes.

00:45:37 The number of genes of microbes present in the human body is between 2 and 20 million.

00:45:42 This means that technically, we are not so many people as microbes.

00:45:46 But it does not matter, the genome of microbes completes ours.

00:45:50 Such a model of existence is a real opportunity mine for medicine.

00:45:54 Human microbiomes include bacteria, fungi and other microorganisms.

00:45:59 They are divided into many species and each type fulfills its own functions.

00:46:03 Some microbes are responsible for extracting vitamins from food.

00:46:07 Others help to break down harmful substances.

00:46:10 Another type helps your stomach to digest food.

00:46:13 A distinct group regulates your immune system,

00:46:16 protects it against worms, parasites and viruses.

00:46:19 Some control your weight.

00:46:21 In simple terms, microbes improve your life, help your body to function

00:46:25 and have a great influence on your health.

00:46:28 There are microorganisms that cause diseases.

00:46:31 They alter immunity or affect vital organs.

00:46:34 Imagine that you know exactly which bacteria are responsible for your poor health.

00:46:38 Then you find a way to get rid of them.

00:46:40 It can be a pill that will be a poison for these microbes.

00:46:44 You take it and the remedy removes all the invisible parasites inside your body.

00:46:48 A disease can also appear because of a lack of good microbes.

00:46:52 It is one of the ways that doctors treat and cure people everywhere on Earth.

00:46:56 Let's say you found a group of microbes that help to strengthen the muscles.

00:47:00 Then you discover which oligoelements help these bacteria to work faster and more efficiently.

00:47:06 You add these vitamins to your food or you simply buy a pill containing a billion of these microbes.

00:47:12 Result! Your muscles develop twice as fast.

00:47:15 The presence or absence of certain microbes indicates the state of your body as a whole.

00:47:19 A sample of your microbes can reveal your health level or the presence of a disease.

00:47:25 So anyone can help their body to get better not only thanks to genetics,

00:47:29 but also thanks to microbial medicine.

00:47:32 The production of human microbes is cheaper, more efficient and faster than genetic modifications.

00:47:37 They are complex and expensive.

00:47:39 This field is just beginning to develop, but we have already made some discoveries.

00:47:43 In the past, humanity thought that microbes were enemies.

00:47:46 We have invented many ways to destroy bacteria and viruses.

00:47:50 But in addition to harmful microbes, these remedies get rid of the good ones.

00:47:54 Now, scientists have understood that microbes can both save lives and destroy them.

00:47:59 So they have launched large-scale research on this subject.

00:48:03 Let's look at the case of a giant panda.

00:48:05 This animal, which has a lot of fat under its skin, is omnivorous.

00:48:09 It rarely eats meat.

00:48:11 Its diet is mainly made up of bait and bamboo shoots.

00:48:15 But in winter, there is nothing like that, so pandas feed on bamboo leaves.

00:48:19 This food is low in calories.

00:48:21 It contains almost no protein.

00:48:23 But despite everything, pandas have not lost weight after a cold winter.

00:48:27 Recently, scientists have discovered the reason for this.

00:48:30 It is thanks to a unique microbiome.

00:48:33 Every winter, a large number of unique bacteria are born in their intestines.

00:48:37 These microbes extract and synthesize the useful substances

00:48:41 found in bamboo leaves better than others and also preserve the weight of the panda.

00:48:46 Scientists have put these bacteria in mylos.

00:48:49 The little rodents have started to gain weight much faster.

00:48:52 Burgers, cakes and other rich foods contain calories and promote the development of colonies of microbes

00:48:58 that contribute to weight gain.

00:49:00 These millions of species of microbes have millions of different functions.

00:49:04 In theory, each of these functions can be used for the good of humans.

00:49:08 Imagine that you need to lose or gain weight,

00:49:11 and that you just add these microbes to your breakfast.

00:49:14 Do you want to sleep better or fight drowsiness?

00:49:16 Drink microbes that will have an effect on the production of sleep hormones.

00:49:20 Do you want to strengthen your bone tissue? No problem!

00:49:23 Bacteria are not only inside our body.

00:49:26 They are everywhere.

00:49:27 A large part of the planet is made up of microbes.

00:49:30 These tiny organisms multiply constantly.

00:49:33 Look, there are a billion of them on your keyboard.

00:49:36 A bacteria grows in size and divides into two bacteria.

00:49:39 After a few minutes, these two new bacteria grow in size and divide in turn.

00:49:44 Four microorganisms appear.

00:49:46 Each of them divides into two.

00:49:48 The colony of bacteria develops rapidly.

00:49:50 With such a rapid reproduction,

00:49:52 a microbe can make a ton of descendants in just 24 hours.

00:49:56 After 5 days, these bacteria will fill all the seas and all the oceans.

00:50:00 They will weigh more than the entire planet.

00:50:03 In ideal conditions, the bacteria could take over the entire world.

00:50:07 However, this will never happen.

00:50:09 The conditions are not united for an uncontrolled bacterial growth.

00:50:12 The speed at which they multiply is equal to the speed of their destruction.

00:50:16 Dryness, water, light, high temperatures, gases, humidity,

00:50:21 all these phenomena help control their populations.

00:50:24 At the same time, microbes are responsible for most of the chemical reactions on Earth.

00:50:29 An old rotten apple on the ground because of microbes and bacteria.

00:50:32 Mold forms on bread because of microorganisms.

00:50:36 But they do not just exist and affect the state of all living materials and other creatures.

00:50:41 An endless war for survival is constantly going on in the world of microorganisms.

00:50:46 Giant bacteria absorb the smallest ones.

00:50:49 Spiky microbes attack long microbes.

00:50:52 There are also viruses that penetrate bacteria to infect them with their cells.

00:50:57 A small ball containing a virus can destroy an entire colony of microbes.

00:51:02 Viruses multiply and take up more and more territory,

00:51:05 until they fall on strong immune cells.

00:51:08 There are also creatures that look like robots.

00:51:11 They look like diamonds with mechanical legs.

00:51:15 Despite this unusual appearance, they are 100% natural.

00:51:19 They are called bacteriophages.

00:51:21 Their only purpose is to destroy all bacteria.

00:51:24 Bacteriophages are an additional protection of the planet

00:51:27 against the uncontrolled reproduction of microbes.

00:51:30 When some microorganisms multiply, they leave waste in decomposition.

00:51:35 These waste are harmful to humans.

00:51:38 Bacteriophages fight these microbes and save our lives.

00:51:41 The coolest thing is that these defenders do not seek to take control of the planet.

00:51:46 They only attack bacteria.

00:51:48 Every second, billions of microbes fight billions of bacteriophages

00:51:52 on all surfaces, like in a video game.

00:51:55 The bacteriophage jumps on the bacteria and injects its genetic code inside.

00:52:00 This code is made up of separate elements that connect to each other inside the body of the microbe

00:52:06 to form a new bacteriophage.

00:52:08 After that, it destroys the bacteria inside and attacks the next one.

00:52:12 Look carefully at the tip of your finger.

00:52:14 There are a lot of lives in this place.

00:52:16 The strongest survive, the weak ones disappear.

00:52:19 Wash it and new bacteria will arrive with water.

00:52:22 Then, wipe your wet finger with a towel and new microbes will jump on you.

00:52:26 The battle is endless, and it's only the tip of your finger.

00:52:30 Inside your body, some bacteria fight for your health against microbes that want to harm you.

00:52:35 Some microbes in our intestines can be responsible for our good or bad mood.

00:52:40 There are also parasitic bacteria that can affect our brain, our way of thinking and our emotions.

00:52:46 Some creatures control the behavior of animals and insects.

00:52:50 Scientists are constantly making discoveries in the world of microorganisms.

00:52:54 Bacteria are therefore masters of our world.

00:52:57 They appeared long before humans and the first animals.

00:53:00 And most likely, they will remain after us.

00:53:03 There is the matter to think about.

00:53:05 Nobody really knows what the appendix is for.

00:53:10 But it is always at the end of a book.

00:53:12 Oh no, it's not the right appendix.

00:53:14 Some researchers consider that the human appendix helped our ancestors to digest the bark of trees

00:53:19 and other foods that they ate at the time.

00:53:22 Since then, our diet has been balanced, and our appendix could disappear without any consequences.

00:53:28 Wisdom teeth also have no use.

00:53:32 Yes, they were useful before the invention of the dentist, but we can do without them now.

00:53:38 Your brain grows by about 2% if you venture into space.

00:53:43 With terrestrial gravity, we think that the fluids in the brain flow down when we stand up.

00:53:49 But microgravity prevents this process from occurring,

00:53:53 and the fluids accumulate in the brain and in the cranial box.

00:53:57 When you get older, the size of your brain gradually decreases.

00:54:01 At 75, the brain is smaller than 30 years old, and it starts to shrink from 40 years old.

00:54:07 It happens to everyone, so you just have to accept it and always train your brain.

00:54:13 If you look carefully at your eyes in a mirror, you will notice a small pink circle in the corner of the eye.

00:54:19 This is your third eyelid.

00:54:21 Useless for humans, it is very useful for animals, especially for birds.

00:54:25 It protects the eyes from dust.

00:54:27 If you've ever heard of natural selection, you know what I'm talking about.

00:54:31 Natural selection maintains some parts of the body through generations, but some are harmful.

00:54:37 So if an element is dangerous or useless, it disappears the next generation, like the third eyelid, for example.

00:54:43 It's not just our brain that shrinks over time.

00:54:46 We shrink too.

00:54:48 Our bones become more fragile and the spine is compressed.

00:54:52 Conversely, when you sleep and you relax, your bones relax too and you wake up bigger than the day before.

00:54:58 Our ears help us maintain balance.

00:55:03 They are not just used to hear.

00:55:05 Our inner ear contains our vestibular system.

00:55:08 The channels of the inner ear contain fluids and small sensors that look like hairs and that allow you to maintain balance.

00:55:15 As far as hairs are concerned, only a few parts of the body are not covered.

00:55:19 These are the palms of the hands, the plants of the feet and the lips.

00:55:23 There are even hairs in the navel that protect it from impurities.

00:55:27 Mine do their job very well.

00:55:29 And not just impurities.

00:55:31 Our navels host a varied fauna.

00:55:34 There are more than 70 different bacteria.

00:55:37 Some of these bacteria are also present in the ground in Japan and others in the ice caps.

00:55:43 You see, there is a real navel operation going on in your navel and you didn't know it.

00:55:48 Only 43% of yourself is really there.

00:55:53 You are made up of 50% of small creatures that live mostly in your intestine and other parts of the body.

00:55:59 Although the number of your cells is less than the number of bacterial cells, you still have 100 trillion.

00:56:06 Knowing this, your genes finally correspond to less than half of what constitutes you.

00:56:12 If we consider all the microbes that live in your body and that we count their genes,

00:56:17 we will talk about 2 to 20 million genes and their combinations.

00:56:20 When you sleep, it is not certain that your whole body is sleeping too.

00:56:25 Sometimes, the brain works even harder when you are asleep.

00:56:30 It has to process tons of information and the calculations take time.

00:56:35 One thing that really rests when you sleep is your nose.

00:56:39 It is impossible to smell while sleeping.

00:56:42 The smell goes off at night.

00:56:45 If it smells very bad in your room, you won't even notice it.

00:56:50 Scientists thought that humans could smell 10,000 times as bad as us.

00:56:55 But no. Recent research has shown that humans can smell 1 trillion times as bad as us

00:57:00 and that we are still deeply rooted in our memory.

00:57:03 They can also send us back to old memories.

00:57:07 By the way, our most intense memories are often made up.

00:57:11 The central memory works like this.

00:57:14 It gives us the certainty that our memories are real.

00:57:17 Even if some details are a bit far from the truth.

00:57:21 No problem if I call you a mammal, right?

00:57:24 We are the only mammals that can walk on two limbs and maintain this posture for the rest of our lives.

00:57:31 You will tell me that kangaroos and gorillas move in the same way.

00:57:36 But kangaroos use their tails as a third leg

00:57:39 and gorillas use their arms to keep balance.

00:57:43 Your bones play a role in your metabolism.

00:57:46 Since they are mainly made up of calcium,

00:57:49 the bones begin to relax if there is not enough in your body.

00:57:54 On the contrary, when there is too much calcium in your blood, it is stored in the bones.

00:58:00 Our size, the shape of our body and our skin color depend on where our ancestors lived.

00:58:07 But we can also adapt to new conditions throughout our life.

00:58:11 For example, if you move from the plain to the mountains,

00:58:15 you will produce more red blood cells to compensate for the lack of oxygen.

00:58:19 And of course, if you move from a cold climate to a warmer climate,

00:58:24 your skin will slightly change pigmentation to adapt.

00:58:28 Our lifespan is programmed in our cells.

00:58:31 They renew and divide constantly, but they have an internal countdown that stops at some point.

00:58:37 Some cells also stop reproducing before others.

00:58:41 On average, cells stop dividing when they reach 100 years.

00:58:45 If we could find a way to reset the countdown, we could potentially live forever.

00:58:51 But we would have a lot of wrinkles.

00:58:54 Fat is used as an insulator, energy reserve and bumper.

00:59:00 Your body accumulates most of the fat around your waist,

00:59:04 since this is where the internal organs are located.

00:59:07 If something happens, this layer of fat can protect your organs from major damage.

00:59:12 Your skull is not made up of a single bone.

00:59:15 It is made up of 22 different bones, most of which are glued to protect your brain.

00:59:20 The jawbone, in other words the lower jaw,

00:59:23 is the only bone in the skull that is attached to your head by conjunctive tissues and muscles.

00:59:27 That's why it's so mobile.

00:59:29 You can move it in all directions.

00:59:32 And the smallest bone in the body is located in the ear.

00:59:36 It's called the "calf" and it's not bigger than a grain of rice.

00:59:40 The most powerful muscles of your body are not only in your legs and arms.

00:59:44 There are some in your head.

00:59:46 It's the masseter, the chewing muscle.

00:59:49 It needs to be powerful enough to ensure chewing.

00:59:53 And you see the muscles that allow you to move your ears?

00:59:56 These are temporal muscles and they are located above the temples.

00:59:59 They also help you chew your food.

01:00:02 We have two really fast muscles.

01:00:04 The muscles that control the tilting of the eyelids.

01:00:07 These are the fastest muscles of our body.

01:00:09 Our eyes are fragile and they must be protected.

01:00:12 When necessary, these muscles close the eyes in less than a tenth of a second.

01:00:17 We can only distinguish the colors purple-blue, green-yellow and yellow-red.

01:00:22 Everything else is a mixture of the three.

01:00:25 It's impossible to calculate the number of color combinations visible by the human eye

01:00:29 since each person sees things slightly differently.

01:00:33 It's still a million combinations on average.

01:00:37 Your stomach has an incredible capacity.

01:00:40 Up to one and a half liters of liquid.

01:00:42 It's the equivalent of a large bottle of Coca-Cola.

01:00:45 It's difficult to evaluate the amount of solid food that can be stored there

01:00:49 since the food is ground by the teeth before it reaches the stomach.

01:00:52 There's not enough room for a whole turkey.

01:00:55 But who knows? A good chicken could fit in there.

01:00:59 I told my grandmother, "There's always room for ice cream."

01:01:04 Show me where this stomach is full of Coca, chicken and ice cream.

01:01:08 If you point to your stomach, it's wrong.

01:01:11 The stomach is between your ribs.

01:01:13 Your stomach is filled with intestines.

01:01:16 The human body is a perfectly balanced machine, isn't it?

01:01:19 Well, not really in my case.

01:01:22 Normally, all these parts work perfectly together to allow us to prosper

01:01:26 and, of course, to stay alive.

01:01:28 Each of our organs is essential to our daily activities,

01:01:31 whether it's breathing, walking, talking

01:01:34 or finding brilliant ideas that make humanity advance.

01:01:37 But are they really essential?

01:01:40 Do we really need all these parts of the body?

01:01:43 Or are some of them just old relics

01:01:46 that we came across during this strange game?

01:01:49 What evolution?

01:01:51 The wisdom teeth, for example.

01:01:53 Well, I've been taken them off for a long time.

01:01:55 And yes, these are those pairs of teeth stuck at the bottom of the mouth

01:01:59 that you often have to go to the dentist for.

01:02:01 They are also called the third molar.

01:02:04 And although they can be used to chew food,

01:02:07 many people think they are simply useless.

01:02:11 And know that about 22% of people in the world

01:02:14 don't even have these four molars in their rabe.

01:02:16 When they grow, they are likely to be included,

01:02:20 which means they remain stuck in the bone of the jaw

01:02:23 and cannot come out of the gums properly.

01:02:26 All this because our jaws are often too small to accommodate them.

01:02:30 Some scientists advised, think

01:02:33 that it is because we have evolved towards narrower jaws over time.

01:02:37 Recent data also show that

01:02:39 what we eat when we are children

01:02:41 could also be at risk,

01:02:43 but it is difficult to be sure.

01:02:46 Apparently, consuming difficult foods to chew,

01:02:49 such as raw vegetables and nuts,

01:02:51 can stimulate jaw growth,

01:02:53 while consuming soft and transformed food

01:02:56 can somehow slow it down.

01:02:58 This leaves little room for the teeth at the bottom to develop.

01:03:02 Will they completely disappear in the future?

01:03:04 I guess we, humanoid mammals,

01:03:07 will have to wait to see what they estimate.

01:03:10 Now let's talk about the vomeronasal organ,

01:03:13 or as I like to call it, the secret instrument of the nose.

01:03:16 You see, rodents and other mammals

01:03:19 have this formidable ability to communicate with each other

01:03:22 thanks to chemical signals called pheromones.

01:03:25 And guess what?

01:03:26 They have a special organ,

01:03:28 the vomeronasal organ, or OVN,

01:03:30 which helps them detect these pheromones.

01:03:32 This is where things get interesting.

01:03:35 While most adult human beings

01:03:37 have something that looks like an OVN in their nose,

01:03:41 it turns out that it is essentially a useless vestige.

01:03:45 Neuroscientists even claim that

01:03:47 if we examine the anatomy of this organ,

01:03:49 we can't tell any cell from any other mammal

01:03:52 that looks like a similar organ.

01:03:54 Moreover, in humans,

01:03:56 this organ doesn't seem to communicate with the brain.

01:03:59 There's not only bad news, however.

01:04:01 Even if the human OVN has little interest,

01:04:04 it seems that it can still react to certain pheromones.

01:04:07 Will humans keep this organ

01:04:09 on their list of ongoing evolutionary projects?

01:04:12 For now, let's put it in the pile of "maybes".

01:04:15 And now, here's a little story.

01:04:17 Animals with a tail need this structure for many reasons.

01:04:21 Some need it for their balance,

01:04:23 others to move,

01:04:25 others to attract potential partners.

01:04:28 But did you know that when we are a few weeks older

01:04:31 in our mother's womb, we also have a tail?

01:04:34 That's right.

01:04:35 We have a complete little tail with its own vertebrae.

01:04:38 As we develop,

01:04:40 this tail disappears like magic

01:04:42 and we only have our faithful coccyx.

01:04:45 Humans and great apes

01:04:47 have the particularity of not having a tail,

01:04:49 unlike other primates.

01:04:51 The reason why great apes lost their tails

01:04:54 remains a mystery.

01:04:56 But we all agree that it distinguishes us

01:04:58 from baboons and other macaques.

01:05:01 However, from time to time,

01:05:03 a human is born with a vestigial little tail.

01:05:06 It's cute, isn't it?

01:05:07 But don't get too excited,

01:05:09 because these tails don't have vertebrae

01:05:11 and can sometimes be associated

01:05:13 with a pathology of the spine.

01:05:15 Anyway,

01:05:16 these tails are generally harmless

01:05:18 and can be easily removed

01:05:20 by a quick surgical intervention.

01:05:23 And let's be honest,

01:05:24 it's not like we're going to miss it.

01:05:26 After all,

01:05:27 who needs a tail

01:05:29 when you have arms and legs to move?

01:05:32 And then, can you only imagine trying

01:05:34 to find pants your size

01:05:36 with a tail that protrudes in the back?

01:05:38 It's not very aesthetic.

01:05:40 It's unlikely that humans will need a tail in the future.

01:05:43 So I guess future generations

01:05:45 can already say goodbye to these tail bones.

01:05:48 Humans also have a funny little membrane fold

01:05:51 in the inner corner of the eyes

01:05:53 called the semilunar fold of the conjunctive.

01:05:56 It's actually a CE that remains

01:05:58 of a third eyelid

01:06:00 that we still find in some animals,

01:06:02 like gorillas and other primates.

01:06:05 But the most curious thing is that even our close parents,

01:06:08 like chimpanzees,

01:06:10 have this little fold that seems useless.

01:06:12 So we're not the only ones

01:06:14 with this weird eye fold.

01:06:16 Speaking of unusual membranes,

01:06:18 they play various roles in different animals,

01:06:21 such as eye protection against dirt and moisture

01:06:24 or iris dissemination against predators.

01:06:27 Some species can even see

01:06:29 through their transparent membranes

01:06:31 when they are underwater or underground.

01:06:33 Now, the reason why we humans

01:06:36 have a third eyelid remains a bit mysterious.

01:06:39 Maybe the evolution of our habitat

01:06:41 and the physiology of our eyes

01:06:43 made it useless.

01:06:45 Or maybe we've become too cool

01:06:47 to have a third eyelid.

01:06:49 Who knows?

01:06:50 With or without vestigial organs,

01:06:52 it's interesting to imagine

01:06:54 what humans could look like in the future.

01:06:57 Many organs have become obsolete

01:06:59 due to the evolution of our way of life.

01:07:02 Would you like to take a look at

01:07:04 what we could look like in the future?

01:07:07 And in the same vein or artery,

01:07:09 have you ever heard of the concept

01:07:11 of the "textile claw"?

01:07:13 It's when you spend so much time

01:07:15 typing on your phone or laptop

01:07:17 that your hand starts to have cramps

01:07:19 that give it a form of claw.

01:07:21 And this is just one of the physical changes

01:07:23 that could happen to us

01:07:25 if we don't take care of our body

01:07:27 in this world dominated by technology.

01:07:29 But our hands are not the only ones concerned.

01:07:31 We could end up with 90-degree elbows

01:07:33 by constantly holding our devices

01:07:35 at this angle.

01:07:37 And even a smaller brain

01:07:39 due to all the distractions

01:07:41 and overload of information.

01:07:43 Well, I know what you're thinking.

01:07:45 We're not going to give up technology

01:07:47 and go back to the Stone Age.

01:07:49 And you're probably right.

01:07:51 We don't have to get there.

01:07:53 But we have to be aware of the potential

01:07:55 negative effects and take measures

01:07:57 to reduce them.

01:07:59 That's why a team of designers

01:08:01 has come to present Mindy to us.

01:08:03 A human of the future whose body

01:08:05 would have changed physically

01:08:07 depending on the constant and endless use

01:08:09 of smartphones, laptops

01:08:11 and other types of time-warp devices.

01:08:13 Although the exaggerated alterations

01:08:15 of Mindy's body may not represent

01:08:17 our near future,

01:08:19 the concerns that underlie them are very real.

01:08:21 So what can we do?

01:08:23 One suggestion would be to

01:08:25 regularly move away from our screens

01:08:27 and to slouch our legs a little.

01:08:29 Or maybe even encourage yoga

01:08:31 in the office or dance parties

01:08:33 to let blood flow.

01:08:35 It is not necessary to completely

01:08:37 give up technology, but we must be aware

01:08:39 of its effects on our body and mind.

01:08:41 In several years,

01:08:43 we could even become smaller.

01:08:45 A scientist estimates that if we were smaller,

01:08:47 our body would need less energy.

01:08:49 Which would be very useful

01:08:51 on our planet more and more overpopulated.

01:08:53 It's funny to think how

01:08:55 our lives are different today

01:08:57 than hunter-gatherers.

01:08:59 At the time, we had to interact

01:09:01 only with a handful of people every day.

01:09:03 Today, remembering everyone's names

01:09:05 is a very important feature.

01:09:07 And we could even

01:09:09 be led to improve it.

01:09:11 And know that technology could

01:09:13 actually play a role in our evolution.

01:09:15 Some researchers think that one day

01:09:17 we could have implants in our brain

01:09:19 that would help us remember people's names.

01:09:21 It's like having a biological

01:09:23 annular directly in your body.

01:09:25 Wouldn't that be convenient?

01:09:27 And who knows, maybe in the future

01:09:29 we will even have a visible technology

01:09:31 that will be part of our appearance.

01:09:33 Imagine an artificial eye capable

01:09:35 of perceiving different colors and images.

01:09:37 And I'm not even talking about what

01:09:39 we could look like if we colonized Mars.

01:09:41 Because of its low gravity,

01:09:43 our body could change in all kinds of ways.

01:09:45 We could have longer arms and legs,

01:09:47 even hair as long as our ancestors

01:09:49 from Neanderthal.

01:09:51 It is difficult to determine

01:09:53 what we could look like in the future

01:09:55 without having very precise data

01:09:57 to test these projections.

01:09:59 But we can say that these changes

01:10:01 will be at least interesting.

01:10:03 As for me, the least we can say

01:10:05 is that it's too late.

01:10:07 I've already said more than 1,400 words

01:10:09 and it's time to leave.

01:10:11 See you later.

01:10:13 Let's go to Antarctica.

01:10:15 Come on, you have time to prepare.

01:10:17 Don't forget to dress warmly.

01:10:19 And here we are in the middle of

01:10:21 the coldest part of the planet.

01:10:23 At some places, the temperature

01:10:25 goes down to -93°C.

01:10:27 It's so cold that if you throw

01:10:29 hot water from a cup,

01:10:31 it will probably touch the ground

01:10:33 in the form of an ice cube.

01:10:35 But this cold is hot compared

01:10:37 to the definition of absolute zero.

01:10:39 Scientists measure it on the scale

01:10:41 of Kelvin, where zero is the lowest point.

01:10:43 That's why there's nothing

01:10:45 colder than this temperature.

01:10:47 This whole object is made up

01:10:49 of atoms and molecules.

01:10:51 When the temperature of an object increases,

01:10:53 these molecules move quickly

01:10:55 and chaotically,

01:10:57 releasing kinetic energy.

01:10:59 If the temperature of an object drops,

01:11:01 these molecules slow down

01:11:03 their movement and their energy decreases.

01:11:05 Absolute zero is therefore

01:11:07 the moment when particles stop completely.

01:11:09 There is no more movement,

01:11:11 which means it is impossible

01:11:13 to make it colder.

01:11:15 Zero Kelvin is less than

01:11:17 73°C.

01:11:19 It's about three times colder than Antarctica.

01:11:21 Let's imagine

01:11:23 that scientists have created

01:11:25 an empty room,

01:11:27 and filled it with a gas of absolute zero.

01:11:29 What happens if a human being

01:11:31 enters it? I can't imagine

01:11:33 that it will go well, so let's send Bob.

01:11:35 But don't worry,

01:11:37 it's a crash test model.

01:11:39 Some clarification first.

01:11:41 When a hot object comes in contact

01:11:43 with a cold object,

01:11:45 the molecules exchange energy.

01:11:47 The fast particles transfer their energy

01:11:49 to the slow particles

01:11:51 and begin to slow down.

01:11:53 Thus, an equivalent exchange

01:11:55 occurs and the temperature harmonizes.

01:11:57 But by default,

01:11:59 the molecules move quite slowly

01:12:01 as long as they are not charged with energy.

01:12:03 And at the same time,

01:12:05 if you have a hot object,

01:12:07 you will need more energy to cool it down.

01:12:09 Yes, it's a bit confusing,

01:12:11 so let's get back to the fun part.

01:12:13 So, if you go to absolute zero,

01:12:15 you will freeze in a few seconds

01:12:17 because all your molecules will begin to slow down.

01:12:19 But what will happen to your body?

01:12:21 Let's see what's going on inside

01:12:23 Bob the model.

01:12:25 First of all, his blood vessels shrink

01:12:27 in the coldest places.

01:12:29 The body distributes the blood of the frozen areas

01:12:31 to the vital organs,

01:12:33 such as the liver, kidneys, heart

01:12:35 and brain.

01:12:37 It's like an emergency mode.

01:12:39 The model's body stores energy

01:12:41 for the most important areas

01:12:43 by depriving the less vital areas.

01:12:45 Then a process of the most terrible begins.

01:12:49 The body is made up of billions of cells.

01:12:51 When their molecules

01:12:53 come into contact with a cold temperature,

01:12:55 they slow down and freeze.

01:12:57 Do you remember those

01:12:59 who arrive at the water on the frozen floor?

01:13:01 Take out a bottle from the freezer

01:13:03 and let it defrost at room temperature.

01:13:05 You will notice that the volume of liquid

01:13:07 decreases after a few hours.

01:13:09 And when the water freezes,

01:13:11 it increases in volume.

01:13:13 However, the human body is made up

01:13:15 of more than half of water.

01:13:17 So inside the model,

01:13:19 these cells are covered with sharp ice crystals

01:13:21 that lacerate the internal structure

01:13:23 of the cells.

01:13:25 The model's muscles and blood vessels are torn.

01:13:27 His skin turns dark blue

01:13:29 and his blood freezes in these veins.

01:13:31 A few more seconds

01:13:33 and the model freezes completely.

01:13:35 The temperature of the absolute zero

01:13:37 interrupts all internal processes.

01:13:39 Bob said he wanted to take a breath,

01:13:41 but now it's getting ridiculous.

01:13:43 Moreover, the molecules are not

01:13:45 only in living objects.

01:13:47 These particles are everywhere

01:13:49 and the absolute zero also affects them.

01:13:51 The light rays occupy

01:13:53 the lowest energy position.

01:13:55 Photons slow down

01:13:57 and can no longer move at the speed of light.

01:13:59 Well,

01:14:01 it's time to conclude the experiment.

01:14:03 Except that something is wrong.

01:14:05 And that's where our story

01:14:07 takes a hypothetical turn.

01:14:09 Scientists can't put the molecules

01:14:11 back in motion

01:14:13 and the neighboring particles

01:14:15 no longer give them their energy.

01:14:17 For some reason, the gas can't absorb it.

01:14:19 Ice molecules slow down

01:14:21 its neighbors.

01:14:23 The gas crosses the walls of the room

01:14:25 under vacuum and causes a chain reaction.

01:14:27 The molecules freeze one after the other.

01:14:29 It's like taking a nap

01:14:31 and fattening all the surrounding matter.

01:14:33 The gas zone expands.

01:14:35 The walls, doors

01:14:37 and windows of the lab are frozen.

01:14:39 Scientists are covered in ice.

01:14:41 Then the cloud escapes

01:14:43 the building. It's like a white spot

01:14:45 that never stops growing.

01:14:47 The sun's rays reach it,

01:14:49 but can't move too fast inside.

01:14:51 The zero envelops

01:14:53 the grass, trees, roads

01:14:55 and cars. Scientists

01:14:57 start ringing the alarm bell

01:14:59 as soon as an entire city is inside

01:15:01 and the cloud reaches zero.

01:15:03 The stop of moving molecules

01:15:05 happens so fast that the ice crystals

01:15:07 don't have time to damage the skin

01:15:09 and the body of living beings.

01:15:11 It's not even about freezing,

01:15:13 but annihilating all existing life.

01:15:15 Are oxygen and carbon dioxide

01:15:17 molecules also frozen?

01:15:19 The air becomes denser.

01:15:21 Here,

01:15:23 a man freezes in the middle of a jump

01:15:25 and stays in the air.

01:15:27 Here, the frozen bird

01:15:29 is in volume.

01:15:31 All these things inside the cold zone

01:15:33 look like a 3D image.

01:15:35 Everything is frozen in its movement.

01:15:37 It's like someone

01:15:39 had taken a screenshot of an entire life

01:15:41 before printing it.

01:15:43 While the cloud of absolute zero

01:15:45 continues to expand,

01:15:47 scientists are trying to solve the problem.

01:15:49 The gas grows

01:15:51 and diverges in all directions.

01:15:53 If it swallows the entire Earth,

01:15:55 it will stop all the chemical processes

01:15:57 of our planet.

01:15:59 And without these processes,

01:16:01 our home will be nothing but a sterile rock,

01:16:03 a piece of lifeless matter stuck in time.

01:16:05 However, the real disaster

01:16:09 will not occur when it envelops

01:16:11 the entire surface of the globe,

01:16:13 but when it reaches the heart of our planet.

01:16:15 This can lead to a sufficient

01:16:17 energy release to destroy it.

01:16:19 However, the nucleus

01:16:21 may resist absolute zero.

01:16:23 Anyway, people won't have to

01:16:25 wait for it to happen.

01:16:27 The cold gas meets a volcano.

01:16:29 The lava flows emit a deafening

01:16:31 whistling and freeze.

01:16:33 Black steam clouds rise in the air.

01:16:35 The cold cloud penetrates

01:16:37 the volcano.

01:16:39 The cold and hot meet,

01:16:41 freeing energy.

01:16:43 The volcano erupts and launches

01:16:45 not fireballs, but stalactites,

01:16:47 frozen magma.

01:16:49 During this time, heavy rains

01:16:51 begin to fall all over the planet.

01:16:53 When the two meet in collision with the cold air,

01:16:55 they move away because they have less density.

01:16:57 The liquid appears in the atmosphere

01:16:59 and condenses in the sky.

01:17:01 As a result, while the giant cloud

01:17:03 freezes part of the planet,

01:17:05 the rain clouds flood the other.

01:17:07 At this point, scientists

01:17:09 have finally found a solution.

01:17:11 They have created a gas whose molecular structure

01:17:13 has been modified and which can stop

01:17:15 this temperature of 0 Kelvin.

01:17:17 So imagine that you heat water.

01:17:19 The more kinetic energy

01:17:21 of water molecules increases,

01:17:23 the hotter the water becomes.

01:17:25 The molecules move faster and faster.

01:17:27 But all the particles do not move

01:17:29 at the same speed.

01:17:31 Some of them have an average energy

01:17:33 or even low.

01:17:35 In addition, the state of low energy

01:17:37 of the molecules is the most likely.

01:17:39 This means that only a few particles

01:17:41 move very quickly in hot water.

01:17:43 This distribution of particles

01:17:45 weak and heavily charged

01:17:47 is called the Boltzmann distribution.

01:17:49 It is omnipresent

01:17:51 both in hot objects

01:17:53 and in cold objects.

01:17:55 If we examine any object

01:17:57 at the molecular level,

01:17:59 we will see that there are many more

01:18:01 particles moving slowly

01:18:03 than particles moving

01:18:05 quickly.

01:18:07 Scientists have therefore found a solution.

01:18:09 They have created a gas

01:18:11 that works in the opposite direction.

01:18:13 It contains more moving molecules

01:18:15 than static molecules.

01:18:17 Researchers hope

01:18:19 that this gas will wake up

01:18:21 the particles asleep in the cloud

01:18:23 of absolute zero.

01:18:25 Thus, two gases collide

01:18:27 with each other.

01:18:29 The cold cloud cannot freeze the cloud

01:18:31 at the Boltzmann distribution.

01:18:33 There are too many active molecules.

01:18:35 Thus, billions of active molecules

01:18:37 charge the frozen molecules with energy.

01:18:39 All the molecules start moving

01:18:41 and share their energy with the neighboring molecules.

01:18:43 The objects inside the gas cloud

01:18:45 begin to wake up.

01:18:47 People are slowly regaining their senses.

01:18:49 As soon as the molecules

01:18:51 start moving minimally,

01:18:53 they begin to receive energy

01:18:55 from the sun's rays.

01:18:57 The particles' movement is equally distributed

01:18:59 between the two gas clouds

01:19:01 and life goes back to normal.

01:19:03 The molecular order is restored.

01:19:05 Great!

01:19:07 And our little fable

01:19:09 ends on a happy ending,

01:19:11 even if it is not entirely credible.

01:19:13 No need to worry.

01:19:15 Scientists have certainly been able

01:19:17 to create absolute zero artificially.

01:19:19 But this will never happen in nature.

01:19:21 Such a temperature does not exist

01:19:23 anywhere in the universe.

01:19:25 The particle's movement even exists

01:19:27 in the most remote and darkest

01:19:29 corners of space,

01:19:31 with incredibly low temperatures.

01:19:33 The appearance of absolute zero

01:19:35 is impossible because there will always be

01:19:37 molecules around that move

01:19:39 and share their energy with each other.

01:19:41 By the way,

01:19:43 no human, animal or mannequin

01:19:45 has been injured during the making

01:19:47 of this video.

01:19:49 Is it enough to avoid a trial?

01:19:51 OK, very well.

01:19:53 Most people are convinced

01:19:55 that humans have only five senses.

01:19:57 But this is not entirely true.

01:19:59 Taste, touch, smell, sight

01:20:01 and hearing are not the only

01:20:03 senses we have.

01:20:05 Scientists say that people

01:20:07 have between 9 and 20 senses in total.

01:20:09 Among them, thermoception,

01:20:11 which is the sense of heat,

01:20:13 and equilibrioception,

01:20:15 which is the sense of balance.

01:20:17 There is also the sense of time

01:20:19 that passes, although not everyone

01:20:21 seems to master it perfectly.

01:20:23 Until recently, it was thought

01:20:25 that there were only 8 different blood groups.

01:20:27 But in reality, there are more than

01:20:29 30 known blood groups.

01:20:31 For every kilo of fat you take,

01:20:33 you generate 1 km of new blood vessels

01:20:35 to provide oxygen

01:20:37 and nutrients to your body.

01:20:39 Your stomach produces a new package

01:20:41 every 6 days to avoid

01:20:43 digesting itself.

01:20:45 Nervous cells transmit

01:20:47 1000 nerve impulses per second.

01:20:49 They travel at a speed of 1 to 431 km/h.

01:20:53 Our DNA contains 100,000 viruses.

01:20:55 Scientists have discovered

01:20:57 one that goes back

01:20:59 100 million years.

01:21:01 Your body emits a visible light.

01:21:03 It is at 4 p.m. that you are the brightest

01:21:05 and it is at 10 a.m. that your brightness

01:21:07 is the least obvious.

01:21:09 Unfortunately, this glow is 1000 times

01:21:11 less intense than what your eyes can perceive.

01:21:13 Sweat is mainly water

01:21:15 mixed with proteins,

01:21:17 sugars, ammonia and many other elements.

01:21:19 It even contains tiny amounts

01:21:21 of metals in the state of trace,

01:21:23 such as copper, zinc, nickel,

01:21:25 iron, etc.

01:21:27 What gives a salty taste to sweat

01:21:29 is the sodium it contains.

01:21:31 In addition, the more salt you eat,

01:21:33 the more salty your sweat tastes.

01:21:35 Your body tries to get rid of excess

01:21:37 and the fastest way is to sweat.

01:21:39 If you walk at 3 km/h,

01:21:41 you have to do it for 40 hours in a row

01:21:43 to lose 1 kg.

01:21:45 And it would take you 518 days

01:21:47 and 8 hours to go around the equator.

01:21:49 The human brain is not really wax.

01:21:51 It contains fat, skin cells,

01:21:53 sweat and dirt.

01:21:55 Your brain becomes three times bigger

01:21:57 during the first year of your life

01:21:59 and reaches its full maturity

01:22:01 at the age of 25.

01:22:03 It is composed of 60% fat.

01:22:05 It generates about 23 watts

01:22:07 of electric energy,

01:22:09 which is enough to run a small light bulb.

01:22:11 Humans can't really do

01:22:13 several tasks at once.

01:22:15 Your brain can't do more than one action

01:22:17 at the same time.

01:22:19 It goes from one to the other,

01:22:21 which doesn't save time,

01:22:23 as you might think.

01:22:25 But it increases the possibility

01:22:27 that you make a mistake

01:22:29 or that you are at work

01:22:31 and you try to focus on an important task.

01:22:33 Try chewing gum.

01:22:35 Studies have shown that it can help you

01:22:37 stay focused longer

01:22:39 on tasks that require all your attention.

01:22:41 Some even say it's a better help

01:22:43 to take exams than caffeine.

01:22:45 There's nothing special about chewing gum,

01:22:47 but the act of chewing wakes your brain.

01:22:49 However, the effect doesn't last long,

01:22:51 only 20 minutes.

01:22:53 Embryos develop fingerprints

01:22:55 at 3 months.

01:22:57 They are 4 times harder than concrete.

01:22:59 The most solid bone in your body

01:23:01 is the femur.

01:23:03 It can support up to 30 times the weight

01:23:05 of an adult.

01:23:07 What's even crazier is that our bones

01:23:09 are made of a composite material,

01:23:11 which means they are both hard and elastic.

01:23:13 Sunburns are the result

01:23:15 of exposure to radiation.

01:23:17 When your body's natural defense mechanism

01:23:19 is overwhelmed by trying to fight UV rays,

01:23:21 a toxic reaction occurs

01:23:23 and causes a sunburn.

01:23:25 Chicken skin is an evolutionary

01:23:27 reflex inherited from our ancestors.

01:23:29 The release of adrenaline made their hair stand up,

01:23:31 and they looked more frightening

01:23:33 to the predators that came near.

01:23:35 Your body produces 0.5 to 1.5 liters

01:23:37 of saliva per day.

01:23:39 It helps you digest food

01:23:41 and fight infections.

01:23:43 You also have a lot of bacteria in your mouth.

01:23:45 The average amount of bacteria

01:23:47 in a person's mouth

01:23:49 is almost the same as the number

01:23:51 of people living on Earth.

01:23:53 Each human has about 150,000

01:23:55 hairs on their heads.

01:23:57 Each strand weighs about 13 millimeters

01:23:59 per month. If we added the growth

01:24:01 of each hair, we could reach

01:24:03 a distance of 16 kilometers

01:24:05 in just one year.

01:24:07 Your hair is also much more resistant

01:24:09 than you think. A single strand can support

01:24:11 85 grams, which corresponds

01:24:13 to the weight of an apple. If we combined the strength

01:24:15 of all the hairs on your head,

01:24:17 it could support the weight of two elephants.

01:24:19 The sound of your heart beating

01:24:21 is the sound of the valves opening

01:24:23 and closing.

01:24:25 Your heart does not respond to these cells,

01:24:27 except if you have an injury.

01:24:29 Your corneas are the only parts of your body

01:24:31 that do not receive blood.

01:24:33 They receive oxygen directly

01:24:35 from the air. When you are sitting

01:24:37 or standing, it is easier for you

01:24:39 to remember positive memories

01:24:41 that do you good. Some people think

01:24:43 it's because sitting with your back flat

01:24:45 stimulates blood circulation,

01:24:47 and your brain receives more oxygen,

01:24:49 which helps it to function better.

01:24:51 The man who has the deepest voice

01:24:53 in the world can produce sounds

01:24:55 that humans, including him,

01:24:57 cannot hear at all.

01:24:59 But elephants can hear

01:25:01 these sounds.

01:25:03 The veins look blue because the light

01:25:05 must pass through layers of skin and fat

01:25:07 to reach them. Your skin

01:25:09 disperses a large part of the red portion

01:25:11 of the white light before reflecting the blood.

01:25:13 So there is only the blue light

01:25:15 to bounce back to your eyes.

01:25:17 A person suffering from anosmia

01:25:19 is unable to detect smells.

01:25:21 Phantosmia is the opposite condition

01:25:23 when a person smells a smell

01:25:25 that is not really present.

01:25:27 The human brain has 100 billion neurons.

01:25:29 It is made up of 73%

01:25:31 of water, and it is the same

01:25:33 for the heart. That's why

01:25:35 if your brain loses only 2% of liquid,

01:25:37 you start to feel tired.

01:25:39 This also deteriorates your memory,

01:25:41 decreases your attention capacity

01:25:43 and deteriorates your mood.

01:25:45 The oldest person known

01:25:47 to have blue eyes lived at the age of stone

01:25:49 7,000 years ago.

01:25:51 Your right kidney is probably

01:25:53 smaller and is lower

01:25:55 than your left kidney to make room for your liver.

01:25:57 Your brain makes sure you don't drink

01:26:01 too much or too little water.

01:26:03 After swallowing liquid,

01:26:05 your mouth and throat start to send signals

01:26:07 to your brain to tell it to stop drinking.

01:26:09 Otherwise, you will continue to swallow

01:26:11 water for the 10 to 60 minutes

01:26:13 it takes for your liquid to reach your cells.

01:26:15 Your eyes can see something

01:26:17 for just 13 milliseconds.

01:26:19 And your brain already treats

01:26:21 this image.

01:26:23 An average eye blink lasts

01:26:25 between 100 and 400 milliseconds.

01:26:27 Even if the tongue is not the strongest muscle

01:26:29 of your body, it never gets tired.

01:26:31 It is because of the way

01:26:33 it is designed. It is made up

01:26:35 of 8 interlaced muscles.

01:26:37 The tongue is the only muscle

01:26:39 whose extremities are not linked to a bone.

01:26:41 Other muscles link

01:26:43 two bones to two extremities,

01:26:45 because that is how we pull and make a movement.

01:26:47 There are about 700 different

01:26:49 bacteria in your mouth.

01:26:51 More than 6 billion of them live there.

01:26:53 Your skin is your

01:26:55 largest organ.

01:26:57 It can cover the surface of two

01:26:59 bath towels. It represents

01:27:01 about 16% of the body's weight

01:27:03 and measures about 2 square meters.

01:27:05 If you were to type 60 words

01:27:07 per minute for 8 hours a day,

01:27:09 it would take you 50 years to type

01:27:11 the human genome.

01:27:13 You get tired faster

01:27:15 when it's hot. This happens

01:27:17 because your body tries to keep cool,

01:27:19 which requires a lot of

01:27:21 additional work.

01:27:23 You are therefore tired even if you do nothing

01:27:25 physically demanding.

01:27:27 Your body has 78

01:27:29 organs, but only 5

01:27:31 of them are essential to your survival.

01:27:33 The brain, the liver, the kidneys,

01:27:35 the lungs and the heart.

01:27:37 Your phone is ringing.

01:27:39 It must be something urgent.

01:27:41 But all the gadgets in the house

01:27:43 are silent.

01:27:45 Your ears are ringing.

01:27:47 You can also hear whistling,

01:27:49 rumbling and even rustling.

01:27:51 But all these noises

01:27:53 have no external source.

01:27:55 That's why they are called

01:27:57 ghost sounds. They can occur

01:27:59 in one or two ears,

01:28:01 constantly or from time to time.

01:28:03 They are generally more noticeable at night

01:28:05 than in the morning.

01:28:07 Women have more taste buds

01:28:09 at the surface of their tongues than men.

01:28:11 This is one of the reasons why

01:28:13 35% of women and only 15% of men

01:28:15 are super-tasters.

01:28:17 These are people who feel the flavors

01:28:19 more strongly than others.

01:28:21 Left-handed people prefer to chew

01:28:23 on the left side

01:28:25 and right-handed people, you guessed it,

01:28:27 on the right side.

01:28:29 Even if your fingerprints are damaged,

01:28:31 they will grow back with the same unique pattern.

01:28:33 When they breathe,

01:28:35 only one lung uses 5% of the oxygen

01:28:37 you inhaled.

01:28:39 Hey, can you speak louder?

01:28:43 I just ate a whole pizza.

01:28:45 It's because after eating a big meal,

01:28:47 our hearing tends to be

01:28:49 a little less fine.

01:28:51 During digestion, most of our blood

01:28:53 circulation is directed to the stomach,

01:28:55 which deprives a little of all the other organs.

01:28:57 So, the next time you want

01:28:59 to listen to your favorite band at a concert,

01:29:01 make sure you eat a lighter meal

01:29:03 so that your hearing is optimal.

01:29:05 In addition to our stomach and

01:29:07 our left kidney, we have a magic organ

01:29:09 that can grow back if we

01:29:11 remove a part of it.

01:29:13 Our liver can regenerate by

01:29:15 making new cells called hepatocytes.

01:29:17 They begin to multiply

01:29:19 as soon as the liver has been damaged.

01:29:21 The gravity of the lesion determines

01:29:23 if the liver can regenerate completely

01:29:25 and how long it will take to do so.

01:29:27 Have you ever wondered what's

01:29:29 the worst thing for your body?

01:29:31 Not sleeping or not eating?

01:29:33 It turns out that lack of sleep is more dangerous.

01:29:35 Indeed, if you don't rest,

01:29:37 your body is exposed to

01:29:39 much more risk.

01:29:41 After 24 hours without sleeping,

01:29:43 you can start having memory problems

01:29:45 and have trouble concentrating.

01:29:47 After only 17 hours without sleeping,

01:29:49 you start to feel tired and dizzy,

01:29:51 irritated, tense and more emotional.

01:29:53 OK, I need a nap.

01:29:55 Your pain receptors

01:29:57 also become more sensitive,

01:29:59 which means that everything hurts you

01:30:01 a little more than normal.

01:30:03 Oh, and it also affects your hearing.

01:30:05 What?

01:30:07 On the other hand, you can have

01:30:09 your first 24-hour period without food

01:30:11 before your body realizes

01:30:13 that you have stopped eating.

01:30:15 During the first 8 hours,

01:30:17 you continue to digest the last meals you took.

01:30:19 After these first hours,

01:30:21 you start using the stored fats

01:30:23 as a source of energy.

01:30:25 After 24 hours,

01:30:27 your body will start eating its own proteins,

01:30:29 which means that you will literally

01:30:31 start losing muscle.

01:30:33 Rainwater is not always drinkable.

01:30:35 It can sometimes contain

01:30:37 dangerous bacteria and viruses.

01:30:39 In addition, in highly polluted places,

01:30:41 it can also contain other harmful substances.

01:30:43 Some communities

01:30:45 only depend on rainwater

01:30:47 as the main source of hydration.

01:30:49 But does rainwater have any health benefits?

01:30:51 Not really,

01:30:53 according to current studies.

01:30:55 Some of these dangerous substances

01:30:57 can be eliminated from rainwater

01:30:59 if you boil it.

01:31:01 But it is preferable to be careful

01:31:03 and drink only water that comes from sources

01:31:05 without any risk for human consumption.

01:31:07 We sweat mainly

01:31:09 to regulate our body temperature

01:31:11 and to add a little humidity,

01:31:13 like the one we need in the palm of our hands

01:31:15 to have a better grip.

01:31:17 But sweat doesn't just appear on our skin.

01:31:19 It comes out of about 5 million pores

01:31:21 on our body.

01:31:23 We literally walk on a quarter of our bones

01:31:25 every day.

01:31:27 Our body has a little over 200 bones,

01:31:29 but about a quarter of them

01:31:31 are in a very small surprising area,

01:31:33 our feet.

01:31:35 As we have 26 bones in each foot,

01:31:37 we have 52 in both.

01:31:39 Our eyes produce tears for many reasons,

01:31:41 such as protecting themselves from infections

01:31:43 or eliminating debris such as

01:31:45 smoke and dust.

01:31:47 Or when your baby makes you miserable.

01:31:49 But the amount of tears we produce

01:31:51 is quite surprising.

01:31:53 Up to 113 liters per year.

01:31:55 It's almost enough to fill a bathtub.

01:31:57 Wow, it's overwhelming!

01:31:59 Our blood pressure

01:32:01 wakes up hours before us.

01:32:03 It's because in the morning,

01:32:05 the body produces a lot of hormones

01:32:07 like adrenaline and noradrenaline.

01:32:09 They help us boost the energy

01:32:11 we need during the morning hours.

01:32:13 But they also increase our blood pressure,

01:32:15 which is generally higher

01:32:17 at night and at noon.

01:32:19 During the night, as we should technically sleep

01:32:21 and do no physical activity,

01:32:23 our blood pressure drops

01:32:25 to 20%.

01:32:27 Speaking of vital fluids,

01:32:29 our blood represents about 10%

01:32:31 of our total weight.

01:32:33 We tend to think that our body weight

01:32:35 is mainly made up of muscles,

01:32:37 fat and bone reserves,

01:32:39 but there is much more than that.

01:32:41 In an adult person in good health,

01:32:43 bones represent 15%

01:32:45 of our total weight.

01:32:47 Muscles represent about 40%

01:32:49 to 45%.

01:32:51 Fat reserves, about 15%.

01:32:53 The rest is made up of elements

01:32:55 like skin, tendons, hair

01:32:57 and other nice little things.

01:32:59 Let's see, that's about...

01:33:01 Yeah, 100%.

01:33:03 Your lungs are not twins.

01:33:05 They are brothers and sisters.

01:33:07 Indeed, they are not the same size or shape.

01:33:09 Your right lung is bigger

01:33:11 and tends to weigh more.

01:33:13 Your heart is responsible for that

01:33:15 as it is tilted a bit to the left.

01:33:17 This creates a small cavity

01:33:19 in the left lung called the heart.

01:33:21 The right lung may be bigger

01:33:23 but it is a bit shorter

01:33:25 as it has to make room for the liver.

01:33:27 Like in your house,

01:33:29 everything has to fit.

01:33:31 Many measurements of your body

01:33:33 are quite symmetrical.

01:33:35 If you try on both arms,

01:33:37 your size and the measurements,

01:33:39 you should see how tall you are.

01:33:41 Similarly, specialists can even

01:33:43 make theories about the appearance

01:33:45 of ancient humans.

01:33:47 It seems we have evolved to become

01:33:49 more and more symmetrical

01:33:51 to look more attractive and in better health

01:33:53 to attract partners.

01:33:55 Moreover, as we have evolved

01:33:57 to walk on two legs,

01:33:59 our symmetrical characteristics help us

01:34:01 to move with the least energy possible

01:34:03 as they create a balance.

01:34:05 Humans are not natural champions

01:34:07 in terms of odour, that's for sure.

01:34:09 But our nose can detect

01:34:11 about a trillion different odours.

01:34:13 Scientists continue to research

01:34:15 on this subject and think

01:34:17 this figure could be even higher.

01:34:19 Some dog breeds are able to detect

01:34:21 odours between 10,000 and 100,000 times

01:34:23 superior to ours.

01:34:25 But it turns out that the best nose

01:34:27 of the animal kingdom could be the elephant

01:34:29 due to the quantity and the amazing

01:34:31 number of olfactory receptor genes

01:34:33 it has.

01:34:35 More than 10,000, while humans

01:34:37 and chimpanzees have less than 400.

01:34:39 We tend to consider our little fingers

01:34:41 as our most delicate fingers.

01:34:43 But they have more power than we think.

01:34:45 It turns out that in case of loss

01:34:47 or failure of the ear,

01:34:49 the overall strength of our grip

01:34:51 can decrease up to 33%.

01:34:53 The liquid contained in our stomach,

01:34:55 composed of chlorhydric acid,

01:34:57 potassium chloride

01:34:59 and sodium chloride,

01:35:01 is much more powerful than any

01:35:03 acid food you can think of.

01:35:05 Like lemons, pineapples

01:35:07 or tomatoes.

01:35:09 The pH of the healthy gastric acid

01:35:11 must be between 1 and 3,

01:35:13 that is, just below that of the acid

01:35:15 in a battery.

01:35:17 The strands of our hair are also very resistant,

01:35:19 so resistant that research is being

01:35:21 carried out on them to reproduce

01:35:23 their strength on human-made materials.

01:35:25 A healthy hair should be

01:35:27 able to withstand a weight

01:35:29 of 12 tons.

01:35:31 This is due to a small protein

01:35:33 found in the strands of hair, keratin,

01:35:35 which is also found in nails and skin.

01:35:37 Only one third of humans

01:35:39 have a perfect vision.

01:35:41 Contact lenses are

01:35:43 much more numerous than we think,

01:35:45 as they represent about 66%

01:35:47 of the population.

01:35:49 In addition to the different eye infections,

01:35:51 our vision also deteriorates with age.

01:35:53 When we are born,

01:35:55 our head represents a quarter of our total length.

01:35:57 When we reach 25 years old,

01:35:59 our head no longer represents

01:36:01 more than an eighth of this length.

01:36:03 This is explained by the fact that the size of our head

01:36:05 does not change much as we age,

01:36:07 unlike the rest of our body,

01:36:09 mainly in terms of legs

01:36:11 and torso.

01:36:13 Our brain is a very powerful computer,

01:36:15 and a single cell in the human brain

01:36:17 can contain five times more information

01:36:19 than the Britannica encyclopedia.

01:36:21 You may remember.

01:36:23 We have not yet determined the exact amount

01:36:25 of data it can support,

01:36:27 but in terms of electronics,

01:36:29 the brain's storage capacity

01:36:31 is about 2,500 Teraoctets.

01:36:33 For comparison,

01:36:35 the National Archives of Great Britain,

01:36:37 which has more than 900 years of history,

01:36:39 only take 70 Teraoctets.

01:36:41 This is probably the reason

01:36:43 why our brain needs

01:36:45 the most oxygen compared

01:36:47 to other organs,

01:36:49 about 20% of the total oxygen

01:36:51 that enters the bloodstream.

01:36:53 However, it only represents

01:36:55 2% of our body mass.

01:36:57 Normal activity and the effect of gravity

01:36:59 cause the cartilage of our ankles,

01:37:01 knees, hips, back and neck

01:37:03 to compress slowly.

01:37:05 Once you have rested overnight,

01:37:07 the cartilage returns to normal.

01:37:09 On average, you are about

01:37:11 a centimeter taller in the morning

01:37:13 than later at night.

01:37:15 And that's why we sleep in the so-called "elongated" position.

01:37:17 You are as bald as a monkey.

01:37:19 Oh no,

01:37:21 that's not an insult.

01:37:23 Your fingerprints are not unique.

01:37:25 You hear better if you cover your ears.

01:37:27 Are these statements true

01:37:29 or are they just legends?

01:37:31 When a person lies,

01:37:33 you can unmask them with your nose.

01:37:35 Is that true?

01:37:37 Yep.

01:37:45 Researchers at the University of Grenada

01:37:47 have discovered that when a person lies,

01:37:49 the temperature around the nose

01:37:51 and in the corner of the eyes increases.

01:37:53 This phenomenon was called

01:37:55 "Pinocchio effect".

01:37:57 So what?

01:37:59 Humans have the same amount of hair

01:38:01 as chimpanzees.

01:38:03 Do you believe it?

01:38:05 It's surprising, but it's still true.

01:38:13 The number of hairs on a human body

01:38:15 and on the body of a chimpanzee

01:38:17 or any other monkey of the same size as us

01:38:19 is almost equal.

01:38:21 The only difference is that

01:38:23 human hairs are often thin and colorless.

01:38:25 It's hard to count them.

01:38:27 Your two lungs are identical.

01:38:31 It's likely, but is it true?

01:38:33 It's a legend.

01:38:43 Your left lung is made up of two lobes

01:38:45 while your right lung is divided into three parts.

01:38:47 In addition,

01:38:49 the left lung is a little smaller

01:38:51 to leave room for the heart.

01:38:53 Besides,

01:38:55 your lungs contain about 2400 km

01:38:57 of airways.

01:38:59 That's more than half the distance

01:39:01 between New York and Los Angeles.

01:39:03 They also contain more than 300 million alveoli,

01:39:05 these little air bags

01:39:07 in the shape of a balloon.

01:39:09 You've probably heard of it before.

01:39:11 Eating carrots is good for your sight.

01:39:13 Unfortunately,

01:39:15 it's not true.

01:39:17 And it's not true either

01:39:19 that if you eat carrots,

01:39:21 you see better at night.

01:39:23 They are indeed vegetables

01:39:25 full of vitamin A,

01:39:27 very useful for the body

01:39:29 and for the eyes.

01:39:31 But if you need glasses,

01:39:33 you'll have to wear them

01:39:35 even if you eat lots of carrots.

01:39:37 Some people are naked

01:39:39 when they look at the sun.

01:39:41 And yes,

01:39:43 about 25% of the population

01:39:45 reacts by blinking

01:39:47 when they look at the sun.

01:39:49 This phenomenon even has a name.

01:39:51 The photosternitatory reflex.

01:39:53 Shaving strengthens the hair

01:39:55 and makes them darker.

01:39:57 Is that true?

01:39:59 Yes,

01:40:01 it's true.

01:40:03 But it's not true

01:40:05 that shaving makes your hair darker.

01:40:07 It's true

01:40:09 but it's not true.

01:40:11 Don't worry, it's a legend.

01:40:13 You may feel like your hair

01:40:15 is thicker, grows faster

01:40:17 or changes colour after shaving.

01:40:19 But it's just an illusion.

01:40:21 Shaving cuts the follicle

01:40:23 in a sharp way,

01:40:25 which makes the hair look

01:40:27 thicker and darker.

01:40:29 But if the hair grows back completely,

01:40:31 it will be exactly the same as before.

01:40:33 Your fingerprints are unique.

01:40:35 That's obviously true, isn't it?

01:40:37 The problem with this statement

01:40:39 is that researchers cannot prove

01:40:41 that fingerprints are unique.

01:40:43 It's apparently true

01:40:45 but impossible to verify.

01:40:47 And even if it's improbable,

01:40:49 we could find two people

01:40:51 with the same fingerprints.

01:40:53 Humans have more than five senses.

01:40:55 Is it a legend or reality?

01:40:57 It's a myth.

01:40:59 But it's not true.

01:41:01 It's a myth.

01:41:03 It's a myth.

01:41:05 It's a myth.

01:41:07 It's a myth.

01:41:09 It's a myth.

01:41:11 We have five main senses.

01:41:13 Sight, smell, touch, taste and smell.

01:41:15 But what about thermal perception?

01:41:17 The perception of heat.

01:41:19 Nociception?

01:41:21 The perception of pain.

01:41:23 Or the perception of your body?

01:41:25 The proprioception.

01:41:27 Close your eyes and touch your nose.

01:41:29 That's it!

01:41:31 It's a perfect example of proprioception.

01:41:33 Some experts believe

01:41:35 that humans have between 21 and 53 senses.

01:41:37 Fingers are flipped

01:41:39 when you spend too much time in the water.

01:41:41 It's for your safety.

01:41:43 Is it true?

01:41:45 What do you think?

01:41:47 [Music]

01:41:49 [Music]

01:41:51 Researchers think it's true.

01:41:53 But let's start from the beginning.

01:41:55 Fingers are flipped when blood vessels shrink.

01:41:57 It's the nervous system

01:41:59 that makes blood vessels shrink

01:42:01 when you spend too much time in the water.

01:42:03 Your body removes blood from your fingers.

01:42:05 Blood vessels are thinner

01:42:07 and the skin adapts to their new shape.

01:42:09 That's why it's funny.

01:42:11 Researchers are not 100% sure.

01:42:13 But they think this mechanism

01:42:15 triggers you to have a better grip

01:42:17 with wet hands and feet.

01:42:19 Humans use only 10%

01:42:21 of their brain's capacities.

01:42:23 I hope it's a legend.

01:42:25 [Music]

01:42:27 [Music]

01:42:29 Yes, it is.

01:42:31 We use only 100%

01:42:33 of our brain's capacities.

01:42:35 This organ is still active

01:42:37 even when we sleep.

01:42:39 When you snore,

01:42:41 the frontal lobe,

01:42:43 responsible for your superior thoughts,

01:42:45 and the areas that allow you to perceive your environment

01:42:47 are still active.

01:42:49 Some people see with brighter colors.

01:42:51 How does it work?

01:42:53 [Music]

01:42:55 [Music]

01:42:57 [Music]

01:42:59 [Music]

01:43:01 It's true.

01:43:03 There are three types of photoreceptors

01:43:05 in the eyes of a normal person

01:43:07 that distinguish the colors of blue,

01:43:09 red and green spectra.

01:43:11 Thanks to these photoreceptors,

01:43:13 most people can distinguish

01:43:15 about a million different shades.

01:43:17 But people with tetrachromatism

01:43:19 have four photoreceptors in their eyes.

01:43:21 They can distinguish about 100 million

01:43:23 different shades.

01:43:25 It's an extremely rare anomaly

01:43:27 that affects women more often than men.

01:43:29 But what's funny is that

01:43:31 most people with tetrachromatism

01:43:33 don't know that they see the world

01:43:35 with brighter colors.

01:43:37 You hear better

01:43:39 if you close your ears.

01:43:41 It's a bit of a paradox.

01:43:43 But is it true?

01:43:45 [Music]

01:43:47 [Music]

01:43:49 [Music]

01:43:51 Yes, if you are in a noisy place,

01:43:53 for example in a club or at a concert,

01:43:55 you should close your ears

01:43:57 to hear your friends better.

01:43:59 Press on your tragus.

01:44:01 It's this little cartilage

01:44:03 at the entrance of your auditory tract.

01:44:05 Lean your ear to your friend.

01:44:07 And there you go.

01:44:09 You can avoid hearing loss.

01:44:11 Ah, that would be really convenient.

01:44:13 But is it a legend?

01:44:15 [Music]

01:44:17 [Music]

01:44:19 [Music]

01:44:21 No, it's true.

01:44:23 You just need to pinch your nose root.

01:44:25 [Music]

01:44:27 In doing so,

01:44:29 the brain receives an alarm signal

01:44:31 and slows down all processes in progress,

01:44:33 including hearing loss.

01:44:35 [Music]

01:44:37 OK, you're still watching five episodes

01:44:39 of your favorite show.

01:44:41 You'll sleep more tomorrow to recover.

01:44:43 But is that possible?

01:44:45 [Music]

01:44:47 [Music]

01:44:49 Unfortunately, no.

01:44:51 You can always try to recover

01:44:53 the hours of sleep lost with

01:44:55 naps or early mornings on the weekend.

01:44:57 But that won't change anything.

01:44:59 If you didn't sleep enough

01:45:01 the night before

01:45:03 or if you went to bed late,

01:45:05 the early morning to noon won't change anything.

01:45:07 Worse still, you may feel

01:45:09 dizzy if you sleep too much.

01:45:11 Some people have more

01:45:13 ribs than others.

01:45:15 Is that true or not?

01:45:17 [Music]

01:45:19 [Music]

01:45:21 It's true.

01:45:23 Most people have 12 pairs of ribs,

01:45:25 24 in total.

01:45:27 But out of 200 people,

01:45:29 one has a 25th rib.

01:45:31 It's a cervical rib

01:45:33 that forms at the base of the neck,

01:45:35 above the clavicle.

01:45:37 It can form on the right or left

01:45:39 and even on both sides of the body.

01:45:41 Those who have this extra rib

01:45:43 probably don't know it.

01:45:45 Indeed, it's rare that it forms

01:45:47 completely and can simply look like

01:45:49 body tissue.

01:45:51 In this case, it's not even visible to the X-ray.

01:45:53 You have to wait at least

01:45:55 half an hour before going to bathe

01:45:57 after eating.

01:45:59 You've probably heard this before.

01:46:01 But is it true?

01:46:03 [Music]

01:46:05 It's a legend.

01:46:07 [Music]

01:46:09 We think that after a meal with a beer,

01:46:11 blood moves to the stomach

01:46:13 and causes cramps.

01:46:15 Your muscles would not receive enough blood,

01:46:17 which would cause cramps.

01:46:19 [Music]

01:46:21 But in reality, there is no risk

01:46:23 if you take a bath after eating.

01:46:25 [Music]

01:46:27 You have enough blood left in your muscles.

01:46:29 [Music]

01:46:31 Some people's snoring

01:46:33 is louder than a kitchen robot.

01:46:35 What do you think?

01:46:37 [Music]

01:46:39 [Snoring]

01:46:41 On average,

01:46:43 when someone snores,

01:46:45 the noise does not exceed 60 decibels,

01:46:47 which corresponds to the volume

01:46:49 of a normal conversation.

01:46:51 But sometimes snoring can reach

01:46:53 80 decibels,

01:46:55 which corresponds to the noise of a mixer.

01:46:57 Everyone does not have round pupils.

01:46:59 Is it possible?

01:47:01 [Music]

01:47:03 [Snoring]

01:47:05 [Music]

01:47:07 Yes,

01:47:09 it is possible.

01:47:11 Out of 10,000 people,

01:47:13 two have strange-shaped pupils.

01:47:15 In general,

01:47:17 they look like lock holes.

01:47:19 This anomaly is called colobome.

01:47:21 Surprisingly,

01:47:23 some people with this characteristic

01:47:25 have no vision problems.

01:47:27 [Music]

01:47:29 Let me tell you

01:47:31 a story about queues.

01:47:33 There are human cases

01:47:35 born with a queue.

01:47:37 However,

01:47:39 those born with a queue

01:47:41 have no real advantage,

01:47:43 except for the role of the coccyx

01:47:45 for balance.

01:47:47 Queues have no function

01:47:49 other than their physical presence

01:47:51 since they have no bones.

01:47:53 They are made up of nerves,

01:47:55 vessels and muscles.

01:47:57 Do you think you are a demanding gastronomist?

01:47:59 Do you think coriander tastes like soap

01:48:01 or you can't stand pineapple on a pizza?

01:48:03 Really?

01:48:05 Up to 30% of people

01:48:07 are considered super-tasters

01:48:09 and experience different levels of pleasure

01:48:11 or disappointment with their food.

01:48:13 A food that is bitter for a super-taster

01:48:15 will probably be sweet

01:48:17 for the average taster

01:48:19 which represents 40% of the population.

01:48:21 There are also 30% of people

01:48:23 who feel nothing

01:48:25 and will never find anything they like.

01:48:27 Poor people.

01:48:29 Living without flavor must be hard.

01:48:31 The vast majority of people

01:48:33 are brown.

01:48:35 About 79% of the world population

01:48:37 has this color.

01:48:39 In the past, all humans had

01:48:41 this brown pigmentation

01:48:43 until about 6 to 10,000 years ago

01:48:45 when humans migrated

01:48:47 to northern Europe.

01:48:49 A mutation occurred

01:48:51 allowing the eyes to adapt

01:48:53 to the changes in light.

01:48:55 Blue eyes have become the most common

01:48:57 color of the mutation

01:48:59 and all current blue eyes

01:49:01 are called Chadwick Abernathy.

01:49:03 His friend called him Chad

01:49:05 and he was a stone block mover in Stonehenge.

01:49:07 Well, not really.

01:49:09 Today, blue eyes represent

01:49:11 about 10% of the human population.

01:49:13 Honey and hazelnut eyes

01:49:15 respectively represent 5%,

01:49:17 gray eyes up to 3%,

01:49:19 and the rarest color of the eyes

01:49:21 is green, which only represents 2%.

01:49:23 Even rarer is

01:49:25 iridium heterochromia

01:49:27 where both eyes are of two different colors.

01:49:29 This is hereditary and is also affected

01:49:31 by other genetic factors.

01:49:33 Only 1% of the human population

01:49:35 has this incredibly rare attribute.

01:49:37 Do you have a small hole

01:49:39 in the front of your ear

01:49:41 above the auditory canal?

01:49:43 This is a pre-auricular pit.

01:49:45 During the first 6 weeks

01:49:47 of the child's development,

01:49:49 long before birth, the earlobe,

01:49:51 which is the external part of your ear,

01:49:53 develops. The pre-auricular pit

01:49:55 is formed when the earlobe

01:49:57 does not fully open, which happens

01:49:59 in less than 1% of humans.

01:50:01 Although there are speculations

01:50:03 that this small hole would be the vestige

01:50:05 and branches that we had

01:50:07 from our marine ancestors,

01:50:09 there is nothing solid to confirm this theory.

01:50:11 If you can lick your elbow easily

01:50:13 or touch your thumb with your forearm,

01:50:15 congratulations, you are part

01:50:17 of the minority of people.

01:50:19 But some people have flexibility

01:50:21 at a higher level.

01:50:23 This condition is called hypermobility.

01:50:25 It allows few people to twist their body

01:50:27 in strange positions, like a snake,

01:50:29 put their head between their feet,

01:50:31 make a back bridge,

01:50:33 and all kinds of wide spaces.

01:50:35 But in some cases,

01:50:37 hypermobility can increase sensitivity

01:50:39 because these people have a greater pain.

01:50:41 This area of the brain

01:50:43 is responsible for the treatment of emotions.

01:50:45 90% of people are right-handed

01:50:47 and only 10% are left-handed.

01:50:49 Yes, that makes 100.

01:50:51 But there is also a very low percentage

01:50:53 of people who can use both hands

01:50:55 equally, including writing,

01:50:57 drawing, and doing any task.

01:50:59 The naturally ambidextrous people

01:51:01 represent only 1% of the total population,

01:51:03 that is, about 70 million people.

01:51:05 If you want to check

01:51:07 if you are one of them,

01:51:09 try to write the same sentence

01:51:11 with both hands,

01:51:13 or draw a circle first with your right hand,

01:51:15 then with your left hand.

01:51:17 If there is no difference, congratulations!

01:51:19 By the way, these exercises are very good

01:51:21 to balance the hemispheres of the brain,

01:51:23 whatever your dominant hand.

01:51:25 If you have three hands,

01:51:27 well, that's another video.

01:51:29 Your nails grow faster

01:51:31 on your dominant hand.

01:51:33 In other words,

01:51:35 if you write with your right hand,

01:51:37 you will have more nails on the right.

01:51:39 Ha! And you have to cut your nails more often.

01:51:41 Your nails also grow faster

01:51:43 in summer and during the day.

01:51:45 Your skeleton is completely renewed

01:51:47 in 10 years.

01:51:49 Without surgery.

01:51:51 An adult uses about 200 muscles

01:51:53 to take a single step.

01:51:55 So don't tell me I don't do enough exercise.

01:51:57 Every minute, your body loses

01:52:01 more than 3000 skin cells.

01:52:03 This represents

01:52:05 nearly 200,000 skin cells per hour

01:52:07 and more than 3 kg per year.

01:52:09 Hey! This is the plan to lose weight

01:52:11 by losing skin cells.

01:52:13 Oh! Sign up!

01:52:15 But don't worry,

01:52:17 your skin will be renewed

01:52:19 every 28 to 30 days.

01:52:21 The liver is the only human organ

01:52:23 that can regenerate completely.

01:52:25 It is enough to have 25% of the initial weight

01:52:27 of the liver

01:52:29 to regain its normal size.

01:52:31 Some people can hear

01:52:33 their eyeballs moving

01:52:35 in their orbits.

01:52:37 Wow! It must not be funny.

01:52:39 Unlike other parts of your body,

01:52:41 your ears and nose

01:52:43 never stop growing.

01:52:45 Wow! It must not be funny.

01:52:47 Your skin frays

01:52:49 if you stay in the water for too long.

01:52:51 But not because it absorbs water.

01:52:53 When your body is wet,

01:52:55 your fingers and knuckles

01:52:57 allow you to have a better grip.

01:52:59 You know, like when the tire

01:53:01 tires on your car

01:53:03 adhere better to the road when they are new.

01:53:05 Your eyes are an amazing tool.

01:53:07 They can distinguish 10 million different colors.

01:53:09 Your brain uses more than 20%

01:53:13 of your body's energy, even when you are resting.

01:53:15 When you sleep,

01:53:17 it still consumes almost as much energy

01:53:19 as when you are awake.

01:53:21 In addition, it burns about 330 calories per day.

01:53:23 An adult person has about 25%

01:53:27 of all his water in his feet.

01:53:29 Most of them are tiny but crucial.

01:53:31 If his water is not aligned,

01:53:33 the rest of his body is not either.

01:53:35 You breathe about 20,000 times a day.

01:53:39 Try not to stop.

01:53:41 In fact, I set a personal record

01:53:43 of breathing for several consecutive days

01:53:45 and I plan to beat it tomorrow.

01:53:47 Water is a real paradox.

01:53:51 It is almost five times more resistant

01:53:53 than a steel bar of the same width.

01:53:55 But they can break at the impact

01:53:57 and are rather fragile.

01:53:59 If a person is affected by anosmia,

01:54:01 also called olfactory cystitis,

01:54:03 they cannot distinguish and detect smells.

01:54:05 But they can still feel bad.

01:54:07 Sorry.

01:54:09 You start to feel thirsty

01:54:11 when the loss of water represents

01:54:13 1% of your body weight.

01:54:15 More than 5% and you risk fainting.

01:54:17 A loss of water greater than 10%

01:54:19 of the body weight

01:54:21 and dehydration can kill a person.

01:54:23 Not a nice ending.

01:54:25 The strongest muscle of your body

01:54:29 depends on its weight and that of your jaw.

01:54:31 Yes, mine is far too developed.

01:54:33 At any time,

01:54:37 the memories of the past are replaced by new ones.

01:54:39 It's like a company I used to work for.

01:54:41 At the end of its life,

01:54:45 a normal person can remember

01:54:47 up to 150 trillion pieces of information.

01:54:49 Except where they left their car keys.

01:54:51 Even if the digital fingerprints are seriously damaged,

01:54:55 they grow back with their original pattern.

01:54:57 You don't believe me?

01:54:59 Give him a whip.

01:55:01 The memory capacity of your brain

01:55:03 is equivalent to about 4 Teraoctets

01:55:05 on a hard drive,

01:55:07 which represents more than 8 million photos.

01:55:09 Man is the only living being

01:55:11 who can naturally sleep on his back.

01:55:13 Even monkeys generally sleep

01:55:15 in a sitting position,

01:55:17 leaning on something.

01:55:19 Don't wake them up.

01:55:21 The longest bone is the femur

01:55:23 and not the laughing bone.

01:55:25 And the smallest is in the ear.

01:55:27 It is shorter than a grain of rice.

01:55:29 Do you feel tickles when you tickle yourself?

01:55:31 Normally, you shouldn't.

01:55:33 Unless someone else tickles you.

01:55:35 This happens because the area of the brain's brain,

01:55:37 which monitors the movements,

01:55:39 predicts the sensations caused by your own movements.

01:55:41 Then it sends a signal

01:55:45 to other parts of the nervous system

01:55:47 to cancel these sensations.

01:55:49 But few people can feel ticklish

01:55:51 from their own head.

01:55:53 If you are not one of these people,

01:55:55 touching a new texture

01:55:57 that the brain does not yet recognize

01:55:59 or using a leather massager

01:56:01 can cause you to feel nervous

01:56:03 and relax.

01:56:05 You can also do a tickling test.

01:56:07 If you want to check the work of your vestibular system,

01:56:09 try this simple trick.

01:56:11 Stand on one foot and close your eyes.

01:56:13 Most people lose their balance,

01:56:15 at least during the first try.

01:56:17 Your vestibular system

01:56:19 includes many organs and systems

01:56:21 spread throughout your body.

01:56:23 Together, they allow your body

01:56:25 to remain balanced in different positions.

01:56:27 This system includes the inner ear

01:56:29 and the vision.

01:56:31 This is why it is much easier

01:56:33 to keep your balance in silence

01:56:35 when your eyes are open.

01:56:37 Can you move your ears voluntarily?

01:56:39 Are you popular in parties

01:56:41 because you can do it?

01:56:43 Congratulations!

01:56:45 About 22% of the earth's inhabitants

01:56:47 are able to move their ears.

01:56:49 As for moving both ears at the same time,

01:56:51 only 18% can do it.

01:56:53 Moving your ears was a common thing

01:56:55 among our distant ancestors.

01:56:57 They used to do a series of movements

01:56:59 with their ears.

01:57:01 The group of muscles responsible for this

01:57:03 are called the auriculars.

01:57:05 We don't need them nowadays.

01:57:07 But some people say

01:57:09 that everyone can learn to move their ears.

01:57:11 It only takes time and practice.

01:57:13 Unfortunately, we can't yet

01:57:15 get used to

01:57:17 moving our ears to a sound source

01:57:19 like dogs and cats do.

01:57:21 We can't lend our ears to someone either.

01:57:23 They are difficult to remove

01:57:25 and to attach.

01:57:27 Look at yourself in the mirror.

01:57:31 Yes, right in the eyes.

01:57:33 Do you see this little fold of skin

01:57:35 in the inner corner of the eye?

01:57:37 Well, in the past,

01:57:39 it was a kind of third eyelid

01:57:41 or nictitating membrane.

01:57:43 We can observe it nowadays

01:57:45 in snakes or lizards, for example.

01:57:47 This one had a priori

01:57:49 the same function as the other two,

01:57:51 but we don't really know

01:57:53 how it developed in humans.

01:57:55 The membrane that made it

01:57:57 was not as thick as our current eyelids.

01:57:59 It could moisten the eye

01:58:01 without obstructing the view.

01:58:03 All that is left of it today

01:58:05 is this tiny fold in the corner of the eye.

01:58:07 It is very likely that in the future

01:58:09 it will disappear completely.

01:58:11 And maybe that on this occasion

01:58:13 we will stop waking up

01:58:15 with this little, not very aesthetic crust

01:58:17 that forms in this place at night.

01:58:19 As long as you are still in front of your mirror,

01:58:21 you will see that it is still there.

01:58:23 It is still there.

01:58:25 It is still down there.

01:58:27 Yes, it is your toes.

01:58:29 Say hello to them and goodbye.

01:58:31 Indeed, scientists think

01:58:33 that in the relatively distant future

01:58:35 we will get rid of our toes completely.

01:58:37 Our ancestors, the ancient primates,

01:58:39 needed toes to climb trees more efficiently.

01:58:41 They used both their hands and their feet

01:58:43 to grab the branches of the trees.

01:58:45 This is clearly visible today

01:58:47 in most monkeys.

01:58:49 They have only slender feet

01:58:51 that allow them to cling to the branches.

01:58:53 The mobility of their feet

01:58:55 also allows them to catch objects on the ground if necessary.

01:58:57 For most of us,

01:58:59 picking up a pen that fell to the ground

01:59:01 with our toes is still a rather complex task,

01:59:03 unlike our primate cousins.

01:59:05 Humans have evolved

01:59:07 on a different path.

01:59:09 We started walking standing up

01:59:11 and down trees,

01:59:13 which made our feet stiff

01:59:15 and our toes shorter over time.

01:59:17 Today, we still use our toes

01:59:19 to balance ourselves by moving our weight

01:59:21 from our heels to the tip of our feet,

01:59:23 but our balance point

01:59:25 is now much more centered.

01:59:27 It first moved towards the inside of our feet,

01:59:29 which made our small toes so small

01:59:31 and our big toes so big.

01:59:33 If this balance point

01:59:37 had just been centered outward,

01:59:39 our toes would have more chance of fusing in the future.

01:59:41 Now, turn around

01:59:43 and look at your beautiful back.

01:59:45 If you've ever fallen off a skateboard

01:59:47 or slipped on a plate of ice,

01:59:49 you probably remember

01:59:51 how painful it is to hit a hard surface

01:59:53 directly on the coccyx.

01:59:55 Fortunately for us,

01:59:57 scientists predict that this bone excrement

01:59:59 will soon disappear as we evolve.

02:00:01 The coccyx is another feature

02:00:03 of our primate ancestors.

02:00:05 And yet again,

02:00:07 they needed their tails

02:00:09 to be more mobile among the branches of trees,

02:00:11 to swing from one tree to the other.

02:00:13 It's hard to say

02:00:15 when humans dropped their tails

02:00:17 to never use them again,

02:00:19 but the facts are what they are.

02:00:21 The only thing that reminds us of those glorious days

02:00:23 when we could easily jump from tree to tree

02:00:25 and this little piece of bone

02:00:27 was almost useless at the bottom of our back.

02:00:29 Let's go back to our face now.

02:00:31 Open your mouth and say "Aaah".

02:00:33 If you're lucky enough not to have wisdom teeth,

02:00:37 then you can be proud

02:00:39 to know that you are a pure product of evolution.

02:00:41 As you may know,

02:00:43 teeth are the only part of the human body

02:00:45 that doesn't heal on its own.

02:00:47 If you lost all your teeth

02:00:49 in this dark era

02:00:51 where there were no dentists,

02:00:53 your only option was to

02:00:55 consume only liquid food.

02:00:57 Scientists think that nature

02:00:59 gave us wisdom teeth

02:01:01 to replace the older and worn-out teeth

02:01:03 we have since childhood.

02:01:05 That's why they grow so late in our lives.

02:01:07 But today,

02:01:09 with all the progress

02:01:11 made by dental surgery,

02:01:13 we tend to keep

02:01:15 almost all our teeth intact

02:01:17 until an advanced age.

02:01:19 And even if we lose some,

02:01:21 we can still replace them.

02:01:23 This makes wisdom teeth

02:01:25 a somewhat outdated legacy,

02:01:27 which they seem to understand by themselves

02:01:29 since fewer and fewer people

02:01:31 need to suffer the ordeal

02:01:33 that their adult-age extraction represents.

02:01:35 Speaking of teeth,

02:01:37 we've been talking about teeth

02:01:39 for the last 1000 years.

02:01:41 And it's expected to change even more

02:01:43 in the future.

02:01:45 In fact,

02:01:47 all parts of our body

02:01:49 are the ones that transform the fastest.

02:01:51 When the first humans

02:01:53 survived by hunting and harvesting,

02:01:55 they needed massive and powerful

02:01:57 and larger teeth

02:01:59 to chew raw meat

02:02:01 and grind plants.

02:02:03 When they started cooking

02:02:05 they lost their teeth

02:02:07 and their teeth were damaged.

02:02:09 Over time,

02:02:11 they shrunk more and more

02:02:13 and they will probably continue to do so.

02:02:15 With a lot of food transformed

02:02:17 that doesn't require much chewing,

02:02:19 future humans will probably have

02:02:21 more delicate facial features,

02:02:23 thin jaws and smooth jaws.

02:02:25 Some parts of the body

02:02:27 don't disappear,

02:02:29 but instead,

02:02:31 they come back to life.

02:02:33 The skull at the back of the knee

02:02:35 was only found in about 11% of people

02:02:37 and scientists thought

02:02:39 it would disappear completely and quickly.

02:02:41 But against all odds,

02:02:43 this brave little bone

02:02:45 managed to end up

02:02:47 in the knees of 39% of humans today.

02:02:49 We still don't know

02:02:51 why the fabella came back.

02:02:53 But the most plausible hypothesis

02:02:55 is that we have become

02:02:57 bigger and heavier than our ancestors.

02:02:59 As our diet

02:03:01 has become better and more nutritious,

02:03:03 our size and our life expectancy

02:03:05 have increased.

02:03:07 We are probably at the peak

02:03:09 of our evolutionary size.

02:03:11 And the fabella may have appeared

02:03:13 in our body to provide a smooth surface

02:03:15 to the tendon behind the knee

02:03:17 so that it can slide better,

02:03:19 thus reducing friction

02:03:21 and the risk of damage due to wear.

02:03:23 Speaking of size,

02:03:25 let's go back to our mirror.

02:03:27 Stretch your arms a little.

02:03:29 Look at those pretty biceps.

02:03:31 Unfortunately,

02:03:33 they are probably not as developed

02:03:35 as those of your ancestors.

02:03:37 Everything that comes from evolution

02:03:39 is not always what we consider

02:03:41 to be the best for us.

02:03:43 It is above all a set of characteristics

02:03:45 in principle the best adapted to our lifestyles.

02:03:47 And this is also the case with our muscles.

02:03:49 They have become smaller and stronger over time,

02:03:51 especially in the upper part of our body.

02:03:53 In the past, humans needed

02:03:55 a great muscular power

02:03:57 to carry out all sorts of essential manual work,

02:03:59 such as hunting and transporting prey,

02:04:01 as well as manufacturing tools

02:04:03 and building shelters.

02:04:05 Then it did not become easier.

02:04:07 On the contrary,

02:04:09 ploughing the fields and building complex structures

02:04:11 required a lot of physical strength and endurance.

02:04:13 But with the rise of technological progress,

02:04:15 physical abilities have left more and more

02:04:17 energy dedicated to brain functions,

02:04:19 allowing us to invent machines

02:04:21 that work in our place

02:04:23 sometimes more efficiently.

02:04:25 We are oriented towards a sedentary lifestyle,

02:04:27 spending more and more time

02:04:29 sitting in front of screens.

02:04:31 In general,

02:04:33 our muscles have not ceased to diminish,

02:04:35 because they are less and less necessary.

02:04:37 It is very likely

02:04:39 that as progress progresses,

02:04:41 we will see our strength diminish

02:04:43 and we will have more difficulty

02:04:45 gaining muscle mass.

02:04:47 Our brain is particularly interesting,

02:04:49 because it has evolved

02:04:51 in a rather strange way.

02:04:53 At first, our distant ancestors

02:04:55 had a rather small brain.

02:04:57 But the close relatives of the Homo sapiens,

02:04:59 the Neanderthals,

02:05:01 had a brain larger than that of the average modern man.

02:05:03 As evolution progressed,

02:05:07 the human brain grew larger.

02:05:09 But over the most recent centuries,

02:05:11 it began to shrink,

02:05:13 and no one knows exactly why.

02:05:15 Some experts say that this could have

02:05:17 to do with the change of our lifestyles

02:05:19 and our socialization.

02:05:21 Humans, especially hunter-gatherers,

02:05:23 had to remember every plant and animal

02:05:25 they saw, their property

02:05:27 and how to use this or that thing.

02:05:29 They had more general knowledge,

02:05:31 learning everything their parents knew

02:05:33 and discovering even more by themselves.

02:05:35 Modern humans have a more specialized

02:05:37 knowledge in a certain field,

02:05:39 deepening a specific subject

02:05:41 while relying on their parents for the rest.

02:05:43 While our ancestors worked

02:05:45 mostly in groups,

02:05:47 in which everyone knew more or less everything

02:05:49 and could replace each other,

02:05:51 we tend to form teams

02:05:53 where each member has a specific task

02:05:55 and is replaceable.

02:05:57 After all, the size of the brain

02:05:59 doesn't seem to matter that much.

02:06:01 Orcs and elephants, for example,

02:06:03 have a brain much larger than ours,

02:06:05 which doesn't necessarily make them smarter.

02:06:07 Happier?

02:06:09 Maybe.

02:06:11 And if we look even further into the unknown,

02:06:13 that is, in the millennia,

02:06:15 we could develop incredible characteristics.

02:06:17 Some even say

02:06:19 that if the sea level continues to rise,

02:06:21 humans could adapt

02:06:23 to underwater life.

02:06:25 We could have palmed hands and feet

02:06:27 to swim better

02:06:29 and even develop gills to breathe underwater.

02:06:31 Another scenario,

02:06:33 if we go into space and start colonizing

02:06:35 other planets, we will inevitably

02:06:37 have to adapt to their conditions.

02:06:39 Mars, for example,

02:06:41 has a lower gravity and a much colder climate.

02:06:43 This would probably make humans

02:06:45 bigger and lighter.

02:06:47 But it could also lead them to develop their

02:06:49 hairiness to keep warm.

02:06:51 Planets with a stronger gravity

02:06:53 and higher temperatures would transform,

02:06:55 on the contrary, humans into

02:06:57 hairy, robust creatures

02:06:59 and probably bald.

02:07:01 The possibilities are endless.

02:07:03 Maybe because of social networks,

02:07:05 we will simply become small, blurry shapes

02:07:07 with big eyes and thumbs, and not much else.

02:07:09 It will be so much more convenient to send

02:07:11 messages and likes.

02:07:13 perspective.

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