Facts Proving Evolution Left You with Some Strange Quirks

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Transcript

00:00:00 So get this, if someone managed to uncoil all the DNA in the human body, it would stretch

00:00:06 out to around 10 billion miles.

00:00:09 Hey, do the math!

00:00:10 That's twice the distance from Earth to Pluto.

00:00:13 And that's not the only awesome thing our body is capable of.

00:00:17 Trillions of nerve connections are powering your memory non-stop.

00:00:21 According to studies, after looking at 2,500 images for a mere 3 seconds, most people can

00:00:27 recall if they have seen these pictures with 92% accuracy.

00:00:33 Your body glows, emitting tiny amounts of fairly visible light.

00:00:37 This glow is the product of biochemical reactions going on inside your organism.

00:00:42 The light waxes and wanes throughout the day, but even though it is visible, you can't

00:00:46 detect it with the unaided eye.

00:00:50 From 1 to 6 pounds of your body weight is made up of bacteria.

00:00:54 Anything from 100 million to 1 billion bacteria can live on just one tooth in your mouth.

00:01:00 So please brush.

00:01:01 It's impossible to taste your food without saliva.

00:01:05 All because the chemicals in your food must be dissolved in saliva before they get detected

00:01:09 by your taste buds.

00:01:12 Even though it sounds like a myth, eating too many carrots can indeed turn your skin

00:01:16 orange.

00:01:18 Carrots have high amounts of beta-carotene.

00:01:20 That's a compound that can cause carotanemia.

00:01:23 If you have too much of this compound in your bloodstream, it'll hold on to parts of your

00:01:27 body with thicker skin.

00:01:28 I'm talking about the soles of your feet, your knees, elbows, palms, and even certain

00:01:33 areas around your nose.

00:01:36 But worry not, this condition is not dangerous.

00:01:38 You can easily reverse it by decreasing the amount of beta-carotene-filled foods you consume.

00:01:45 The chin muscles, scientifically known as the mentalis muscles, look pretty quirky,

00:01:50 giving us mixed feelings.

00:01:52 Just look at these creepy tiny tentacles.

00:01:54 And still, they make it possible for us to create all kinds of facial expressions that

00:01:58 involve the lips, chin, and cheeks.

00:02:01 And yes, they are the culprits behind those weird wrinkles and crevices on the skin of

00:02:06 your chinny-chin-chin.

00:02:08 All because these muscles don't pull on themselves, but yank on the skin.

00:02:13 People can live without some organs, leading a normal life.

00:02:16 The human body consists of singular organs and those that come in pairs.

00:02:21 And speaking of the latter, you'll only need one of those to survive.

00:02:25 Your small intestine is actually not so small.

00:02:27 It's taller than you, measuring around 23 feet.

00:02:32 The cornea, that transparent front cover on your eyes, doesn't have any blood supply.

00:02:37 Instead, it receives oxygen directly from the air.

00:02:41 Human beings develop their unique fingerprints very early in life, while they're still embryos,

00:02:46 just 3 months after being conceived.

00:02:49 By the way, even if fingerprints get badly damaged, they tend to grow back to their original

00:02:53 pattern.

00:02:55 All people are born with a diving reflex.

00:02:58 It can get activated and shut bodily functions if one is drowning or is submerged in the

00:03:02 water.

00:03:04 The human brain is by no means smooth.

00:03:07 But if you decided to flatten all those wrinkles covering it, the brain would be the size of

00:03:11 a pillowcase.

00:03:12 But not as useful.

00:03:15 Newborn babies only blink once or twice in a minute.

00:03:18 For comparison, a grown-up person blinks at least 10 times within the same time.

00:03:23 Our lungs are the only organs that can float on the water.

00:03:26 All because they're made up of around 300 million balloon-like structures called alveoli.

00:03:31 Also, even if we're perfectly healthy, our lungs are never completely germ-free or sterile.

00:03:38 Your nose is a superhero.

00:03:40 It's your very own heater, filter, and humidifier.

00:03:44 This organ is lined with tiny bone-like shells called turbinates.

00:03:47 They contain blood vessels capable of heating the air and goblet cells that can help humidify

00:03:52 the air.

00:03:53 Also, the air you breathe gets filtered in your nose before going further to your lungs.

00:03:59 Every time you eat something, your esophagus – the organ your food travels through to

00:04:04 reach the stomach – moves in a series of wave-like contractions, pushing the food forward.

00:04:09 This is known as peristalsis.

00:04:11 There's a bond between your digestive system and your brain – the gut-brain axis.

00:04:17 This is why stress or brain issues can affect the way your body digests food.

00:04:23 Even though hiccups are typically harmless and resolve by themselves after a couple of

00:04:27 minutes, they aren't exactly pleasant.

00:04:29 So you should probably know that they might occur because of changes in temperature.

00:04:35 The density of your brain increases throughout your whole life.

00:04:38 All because new neural connections pop up.

00:04:41 They appear because the structure of the brain keeps changing too.

00:04:45 If you don't want to sneeze, press the skin on the bridge of your nose with your fingers.

00:04:50 When you do it, your brain receives an alarm signal.

00:04:53 Very quickly, it puts the brake on all those other processes, including the sneezing reflex.

00:04:58 By the way, studies have found that sneezing is your nose's way to reset.

00:05:03 A sneeze reboots the cells that line the inside of your nose.

00:05:07 They're called cilia.

00:05:09 The part of your brain that's responsible for vision is in the back of your head.

00:05:14 Interestingly, the right side of your brain controls the vision on the left side, and

00:05:18 vice versa.

00:05:20 If you're in some loud place, for example, in a club or at a concert, close your ears

00:05:25 to better hear your friends.

00:05:28 Push the tragus, which is that pointy skin-covered cartilage in front of the ear canal, into

00:05:32 your ear.

00:05:33 Then, turn this ear toward your friend.

00:05:37 On average, when a person snores, the sound doesn't get louder than 60 decibels.

00:05:41 That's as loud as a regular conversation.

00:05:44 But sometimes, the noise level can reach 80 decibels.

00:05:47 That's as loud as a working food blender.

00:05:51 Just like salamanders regrow their tails, humans might be able to regenerate cartilage.

00:05:56 That's the rubber-like stuff surrounding your joints.

00:05:59 Scientists have recently discovered that cartilage could repair itself.

00:06:03 This process is likely to be the most effective at the ankle, not that effective in the knee,

00:06:08 and the least effective in the hip.

00:06:10 Now, if a person has asnosmia, which is also called smell blindness, they don't distinguish

00:06:16 and detect smells.

00:06:19 Your eyes never stop moving while taking in visual information.

00:06:22 Otherwise, you wouldn't be able to see the whole picture.

00:06:26 These movements go unnoticed because your brain is a great video editor.

00:06:30 It stabilizes the images and connects tons of fragments into one smooth video.

00:06:36 The liver is the only human organ that can regenerate completely.

00:06:40 Even if it's a mere 25% of the original liver weight, the organ can get back to its

00:06:45 full size.

00:06:48 Your mouth burns when you're snacking on pineapple because while you're eating this

00:06:52 fruit, it's eating you back.

00:06:54 Well, kind of.

00:06:55 Pineapple is the only known food that contains bromelain.

00:06:58 That's an enzyme that breaks down proteins.

00:07:01 Luckily, your stomach acid knows how to deal with the offending enzyme.

00:07:06 We also have bacteria that can produce electricity living in our intestines.

00:07:10 These bacteria give off electrons, which creates tiny electrical currents.

00:07:15 This might be the bacteria's way to generate energy.

00:07:19 Deja vu might actually be something like a brain processing lag.

00:07:26 There's a theory claiming that it might happen when your brain is moving information from

00:07:30 one part to another.

00:07:32 If there's even the tiniest delay in that process, your brain will get the same information

00:07:36 twice.

00:07:37 In this case, it'll process it as an event that happened before.

00:07:42 The DEC2 gene mutation allows people to have just a few hours of sleep a night and still

00:07:47 feel great.

00:07:48 They don't get tired and never sleep in.

00:07:51 On average, such people wake up at 4 or 5 a.m.

00:07:55 No more than 5% of the world's population has this feature.

00:08:00 Your ears might pop or even hurt when you're on an airplane.

00:08:04 You can solve this problem by simply chewing some gum.

00:08:07 This opens up your eustachian tube.

00:08:09 That's a small passage that connects your throat and your middle ear.

00:08:13 Opening this passage helps equalize the pressure in your ears and puts an end to the popping.

00:08:18 You can also yawn to open up the eustachian tubes.

00:08:22 Your feet are likely to become bigger with time.

00:08:24 Just like your nose.

00:08:25 And your ears.

00:08:27 You see, when people grow older, ligaments and tendons in their feet weaken.

00:08:31 This makes the arches flatter, and the feet become wider and longer.

00:08:35 It may seem there's nothing exciting about human bones…

00:08:41 Unless you find them in your closet!

00:08:45 But normally, they're hidden under multiple layers of cells and tissues.

00:08:48 They're dense, hard, and unassuming.

00:08:52 But are they?

00:08:53 Your bones not only protect your internal organs and help you move, but also store fat

00:08:59 and minerals.

00:09:00 Your blood cells are produced there.

00:09:02 Most of the bone tissue isn't even solid.

00:09:05 How about going on a journey through your bones to see it with your own eyes?

00:09:09 But you'll need to get through several layers of other tissues first.

00:09:12 To start with, you'll have to squeeze through the skin, your largest organ.

00:09:17 Be careful, it's a labyrinth of hair follicles, sweat glands, nerve endings, and blood vessels

00:09:23 where you can easily get lost.

00:09:25 Right under the skin, there's a layer of fat.

00:09:28 Its main purpose is to keep your body warm.

00:09:30 This layer consists of tiny plastic bags, each with a drop of fat, and you may have

00:09:35 a tough time navigating around these bubbles.

00:09:39 After passing this obstacle course, you're inside your muscles.

00:09:42 Their cells, fibrous and long, are always ready to spring into action, helping you transport

00:09:48 your body wherever you need.

00:09:50 Going through this layer of tissue is tricky because such cells form bundles, and that's

00:09:55 what makes your muscles so strong.

00:09:58 Imagine taking a bunch of rubber bands and stretching them!

00:10:01 Hard?

00:10:02 Your muscle tissue's tough like that!

00:10:04 Finally, you reach your destination and see a thin, dense membrane.

00:10:09 It's the outer surface of a bone.

00:10:11 This layer consists mostly of connective tissue made up of proteins.

00:10:16 You also spot numerous blood vessels.

00:10:18 Their tiny perpendicular branches sneak deeper into the bone to feed bone cells.

00:10:23 You notice that these branches lie in minuscule channels.

00:10:27 The inside of the surface layer is filled with stem cells.

00:10:31 They're the busiest in childhood and become less active when a person grows up.

00:10:36 But if a bone is damaged, they jump back into action and get down to repairing it.

00:10:41 Luckily, all your bones are intact.

00:10:44 But if there was a fracture, you'd see nearby vessels bleeding and forming a thick lump

00:10:49 around the injury.

00:10:50 In about two days, the area would be surrounded by countless bone-producing cells.

00:10:55 They would begin to change, turning into different kinds of cells and forming new bone between

00:11:00 the ends of the fractured one.

00:11:03 Anyway, it's time to move further toward your bone's hardest part – the outer layer,

00:11:08 which is smooth and solid.

00:11:11 Because of its density, it's also called compact bone.

00:11:14 This kind of bone is the reason why X-rays, which can normally pass through nearly anything

00:11:19 (including your body's soft tissues), can hardly get through your bones.

00:11:24 This part makes up 80% of your total bone mass.

00:11:27 It's incredibly hard to squeeze through the compact bone because it consists of numerous

00:11:32 microscopic columns.

00:11:34 Inside these cylinders, there are even more bone-producing cells.

00:11:38 And in the middle, there's a central canal that connects the bone's nerve fibers and

00:11:42 blood vessels.

00:11:44 The cylinders go along the bone and help to prevent it from bending or fracturing.

00:11:49 Once you get through this super hard layer, the picture around changes dramatically.

00:11:53 You're in spongy bone!

00:11:56 True to its name, it looks like a sponge or a honeycomb that consists of tiny needles.

00:12:02 This bone tissue is way less dense than the compact bone, more flexible, and also much

00:12:07 lighter.

00:12:08 You notice that the spongy tissue is only near the ends of the bone you're exploring.

00:12:13 It means you're inside one of the long bones, whose structure is a bit different from others.

00:12:18 In the middle, it has what looks like a tunnel to you.

00:12:21 It's made of compact bone that surrounds a cavity filled with a special substance.

00:12:26 It's called yellow bone marrow, and it's rich in fat.

00:12:31 But it's time to return to the spongy bone.

00:12:33 It's mostly found at the ends of long bones, inside vertebrae, and near joints.

00:12:38 This sponge-like tissue has open spaces in it.

00:12:41 They're filled with red bone marrow, which produces blood cells.

00:12:46 While traveling further through the human skeleton, you discover that it consists of

00:12:50 five types of bones.

00:12:52 Long.

00:12:53 They're much longer than they are wide.

00:12:55 For example, your thigh or upper arm bones, and your toes and fingers.

00:13:00 Flat.

00:13:01 They're thin and slightly curved.

00:13:03 These bones are like a layered cake.

00:13:06 Spongy bone sandwiched between two parallel layers of compact bone.

00:13:10 Your ribs and most of the bones in your skull are flat bones.

00:13:14 Short bones.

00:13:15 Shaped like cubes, they consist of a thin layer of compact bone around spongy insides.

00:13:21 Short bones can be found in your wrists and ankles.

00:13:24 Sesamoid.

00:13:25 These are bones surrounded by tendons, and their main purpose is to hold tendons away

00:13:29 from joints.

00:13:30 There are numerous bones in your feet, hands, and knees, including the kneecap.

00:13:35 These bones got such a name because they look like grains of wheat.

00:13:40 Irregular bones.

00:13:41 These don't fit into any category because their shape is too complicated.

00:13:45 Those are most of the bones of your face and some of your skull.

00:13:50 An adult skeleton's made up of 206 bones, and each of them has its own function.

00:13:55 Interestingly, people are born with nearly twice as many bones, but as you grow up, these

00:14:01 small bones fuse together and form larger ones as a person matures.

00:14:07 If one bone's broken, those around it can't work properly either.

00:14:11 It usually takes about 12 weeks for a bone to heal.

00:14:16 The smallest bone in your body is dozens of times smaller than a penny.

00:14:20 This bone's called the stapes and is located in your middle ear.

00:14:24 The tiny thing weighs as much as two sesame seeds.

00:14:29 You get a new skeleton every 10 years, because every year, 10% of your bone's mineral content

00:14:35 gets renewed.

00:14:37 The average person walks 1 to 3 million steps per year.

00:14:41 That's why bones have to be so resilient, otherwise they wouldn't cope with the pressure.

00:14:47 Your longest and strongest bone is in your leg.

00:14:50 The femur, that's how it's called, runs from your hip to your knee.

00:14:56 Even though your teeth are part of the skeletal system, they don't count as bones.

00:15:01 More than half of all the bones in your body are in your hands and feet.

00:15:06 The only bone in your body that's not connected to another is the tongue bone.

00:15:11 It's a V-shaped bone at the base of your tongue that holds it in place.

00:15:16 One percent of people are born with a 13th rib.

00:15:20 Your bones aren't white, their color's rather yellow or pinkish from the outside and deep

00:15:25 red inside.

00:15:27 That's because of the blood vessels in and around them.

00:15:31 If you fracture a bone, it'll heal on its own by producing new bone cells.

00:15:36 A cast will only help it heal straight.

00:15:40 People have known how to deal with broken bones for ages.

00:15:43 In ancient Egypt, around 1600 years BCE, they realigned fractured bones and bandaged them

00:15:50 with linen.

00:15:52 You can't control your bones, you can only tell your muscles attached to your bones where

00:15:56 to move.

00:15:58 Your bones reach their maximum density at the age of 30.

00:16:03 Only 10% of the world's animals, including humans, are vertebrates, meaning they have

00:16:08 a skeletal system.

00:16:10 A coating of special tissue called cartilage covers a bone and prevents it from rubbing

00:16:15 directly against another one.

00:16:18 The enamel covering your teeth is even stronger than your bones.

00:16:22 It protects the delicate tissue and nerves underneath.

00:16:26 The biggest joint in your body is actually your knee.

00:16:30 It has to be large to connect three equally big bones – the femur, going from your hip

00:16:35 to your knee, the kneecap, and the shin bone.

00:16:39 Some joints hardly move or don't move whatsoever.

00:16:43 Those are between your teeth, inside the skull, and between the first pair of ribs.

00:16:49 Bones store minerals, for example, calcium and phosphate.

00:16:53 They can be released in your bloodstream when necessary.

00:16:57 And finally, the so-called "funny bone" isn't a bone at all.

00:17:01 It's a nerve that runs inside your elbow.

00:17:03 When you hit it, you feel sharp, piercing pain.

00:17:07 The upper arm bone the nerve runs by is called the humerus.

00:17:11 But the pain is clearly not humerus.

00:17:14 It can be funny when it happens to someone else though.

00:17:18 Hey, check it out!

00:17:19 Your bones are designed to be used a lot every day.

00:17:23 Some of them can absorb the force of two or even three times your body weight.

00:17:27 That's impressive, but your teeth are even stronger.

00:17:31 When you bite something, they can withstand incredible pressure – up to 200 pounds!

00:17:36 By the way, the enamel is considered to be a part of your skeletal system.

00:17:41 Whenever you rotate your hand, the bones inside your forearm cross.

00:17:46 Grab hold of your arm and turn your palm to face first upward and then downward.

00:17:50 You'll make sure it's true.

00:17:53 Not only is your body 60% water, your bones contain some liquid too.

00:17:57 About 25% of the human bone mass is made up of water.

00:18:02 The human eye has something in common with a car engine.

00:18:05 They both can't work properly without various liquids.

00:18:08 The eye needs tears as much as the engine needs oil.

00:18:12 Tears should be evenly spread over the surface of your eye.

00:18:15 That's why you blink up to 20,000 times a day.

00:18:18 And your eyelid plays the role of a windshield wiper.

00:18:22 The only part of the human body that doesn't get any nutrients from blood is the cornea

00:18:27 – the clear front surface of the eye.

00:18:29 Instead, it's fed by tears on the outside and special fluids on the inside.

00:18:35 When you blush, it means there's increased blood flow in your body.

00:18:39 And then, not only your cheeks, but also your stomach lining gets somewhat red.

00:18:43 It's because it has plenty of blood vessels.

00:18:46 When there's more blood than usual in 'em, the lining blushes.

00:18:50 Your stomach lining gets replaced every 3-4 days.

00:18:53 This prevents the organ from eating itself.

00:18:56 The digestive acids there are exceptionally powerful.

00:18:59 People can accidentally swallow small objects, such as glass, plastic items, coins, and many

00:19:05 others.

00:19:06 Normally, they don't cause any harm and pass through the digestive tract within 48

00:19:11 hours.

00:19:12 Tiny quantities of plastic you might consume by mistake won't harm you.

00:19:16 But your stomach will have problems with digesting grass.

00:19:20 Grazing animals have special teeth and stomachs to process raw leaves and grass.

00:19:25 People aren't equipped that way.

00:19:28 The stomach is the most important protector of the immune system.

00:19:32 It contains hydrochloric acid.

00:19:34 This acid gets rid of dangerous food toxins, viruses, and bacteria that come along with

00:19:39 the food you eat.

00:19:40 The stomach itself would be digested by this strong acid if the mucous membrane didn't

00:19:46 protect it.

00:19:47 You've got two really fast muscles.

00:19:49 They control your eyelids closing.

00:19:51 They're the swiftest in your body.

00:19:53 Your eyes are fragile and need protection.

00:19:56 When a special reflex is triggered, for example, when something suddenly touches your eye,

00:20:01 these muscles only need 1/10th of a second to shut the eyelids.

00:20:06 Women usually blink more than men.

00:20:08 Plus, the older you get, the more frequently you do it.

00:20:12 By the way, when you watch a movie with a friend, you both blink in unison.

00:20:17 Do you think you owe your firm handshake to your strength workouts?

00:20:20 It's more likely thanks to your pinky.

00:20:23 Just kidding.

00:20:24 Well, the pinky is the strongest finger out there.

00:20:27 It's responsible for 50% of the entire hand strength.

00:20:32 But the most used finger is the thumb.

00:20:34 If a person loses it, their hand becomes 40% less agile.

00:20:38 Oh, and the thumb has its own pulse, thanks to the artery running through it.

00:20:44 Your big toes carry more than 40% of your weight, more than all the other toes combined.

00:20:49 All in all, all your toes are a big deal.

00:20:52 They provide support and balance when you walk.

00:20:55 And when you run, they help you to be faster.

00:20:58 No more than 2% of people have natural red hair.

00:21:02 They're followed by blondes (about 3%) and all kinds of brown shades (about 11%).

00:21:08 But the world's most common hair colors are black and dark brown.

00:21:12 Hair is almost indestructible.

00:21:15 It can be burned or affected by strong acids, but that's pretty much all you can do to

00:21:19 destroy it.

00:21:21 Your hair usually stops growing at a certain length.

00:21:24 And since a hair lives for 2-7 years, its length doesn't normally exceed 42 inches.

00:21:30 Tell that to this lady from China, who got to the Guinness World Records with the longest

00:21:35 hair ever.

00:21:36 In 2004, it was a bit more than 18 feet 5 inches long.

00:21:41 Wow, what a drag!

00:21:44 Nails can grow staggeringly long too.

00:21:47 Some of the longest nails in the world belong to this guy from India.

00:21:50 Their combined length was 29 feet 10 inches, which is almost as long as a London double

00:21:56 decker.

00:21:57 The man cut them off back in 2018.

00:22:00 Nailed it!

00:22:02 Nails do help us catch small objects and peel stickers off.

00:22:05 But that's not all.

00:22:07 If you didn't have a rigid structure to press against, you wouldn't be able to understand

00:22:11 how firmly you should hold things.

00:22:14 Not only your hair and nails, but also your liver can grow.

00:22:18 It's the largest internal organ by mass.

00:22:21 The liver can fully regenerate from only 51% of its original mass back to the full size.

00:22:27 At the same time, constant damage to the liver will result in scars.

00:22:32 The largest organ in your whole body is the skin.

00:22:36 It makes up more than 15% of your total body weight.

00:22:40 People lose 30,000 to 40,000 skin cells every single minute.

00:22:45 That adds up to 9 pounds of skin cells a year.

00:22:48 You know that dust in your house?

00:22:50 Now you know where some of it comes from.

00:22:54 The tongue isn't the only organ that helps you recognize taste.

00:22:57 Your nose also plays a critical role in this process.

00:23:01 It's often said the nose is responsible for 75 to 95% of your taste perception.

00:23:07 Try holding your nose next time you eat.

00:23:10 Gnaw on an onion or eat some smoked fish.

00:23:13 It's not that you won't feel any taste at all, but it's gonna be way blander.

00:23:18 Your taste buds won't work properly if your mouth is too dry.

00:23:22 You simply won't feel the taste until the food is covered in saliva.

00:23:26 It contains enzymes, which are complex protein molecules.

00:23:30 They start to break down your food as soon as it gets into your mouth.

00:23:34 A recent study has found out that people can distinguish more than a trillion smells.

00:23:39 You tend to remember odors better than sounds or images.

00:23:42 That's why smells can evoke distant memories.

00:23:46 When you're asleep, you don't feel any odors.

00:23:49 Your sense of smell basically deactivates at night.

00:23:52 Even if there's some terrible stench in your bedroom, you won't notice it.

00:23:56 I'm sure my dog is relieved to hear that.

00:23:59 The color of your dreams seem to be affected by the TV you watched as a kid.

00:24:04 If it was black and white, you'd probably see monochrome dreams more often than not.

00:24:10 If you're used to color television, your dreams are likely to be colorful.

00:24:15 What kind of dreams did people in the Middle Ages have then?

00:24:18 Knights that say "knee"?

00:24:20 Your heart can give you away when you lie by starting to beat faster.

00:24:25 Women's hearts are usually smaller than men's.

00:24:27 That's why they have to work harder and make more beats.

00:24:30 Otherwise, they won't be able to pump enough blood.

00:24:33 Even if you brush your teeth twice a day and never forget about mouthwash, your mouth still

00:24:38 remains one of the dirtiest parts of your body.

00:24:42 Millions of bacteria live there.

00:24:44 The good news is that most of them are good for your health.

00:24:47 They protect your body from bad bacteria and viruses.

00:24:51 The second dirtiest place is your belly button.

00:24:54 You don't really use it after you were born.

00:24:56 So this forlorn area accumulates all kinds of germs, sweat, and dirt.

00:25:02 The belly button has over 2,300 bacterial species, and it does need extra attention.

00:25:09 They say eyes don't grow with the rest of the body.

00:25:12 Well, it's not 100% true because the eyes aren't fully developed until you're about

00:25:17 21.

00:25:18 But the absolute growth champions here are your ears and nose.

00:25:23 They never stop growing.

00:25:24 Wow, what was that thing about elephants again?

00:25:27 Must've been a different video.

00:25:29 If all your blood vessels were stretched into a single line, dang, you would be in a really

00:25:34 tough spot.

00:25:36 But they would go round the Earth four times.

00:25:39 You can't tickle yourself, no matter how hard you try.

00:25:43 You've just checked that and failed, haven't you?

00:25:46 That's because your brain warns you that you're about to be tickled, which it can't

00:25:49 do if it's someone else.

00:25:52 Ever wondered why you feel so sleepy after lunch?

00:25:55 One of the reasons is your circadian rhythm, which runs on a 24-hour cycle.

00:26:00 It demands that you have a nap 7 hours after waking up.

00:26:04 And the food just adds to this effect.

00:26:06 As simple as that.

00:26:07 Oops, excuse me, it's time!

00:26:11 So check this out.

00:26:13 There are people who can bend down their pinky without bending the ring finger.

00:26:17 But most find it hard or even impossible to do.

00:26:20 When they move their middle or little finger, they tend to slightly bend their ring finger

00:26:24 too.

00:26:25 I do too.

00:26:26 Globe luxation is an extremely rare condition when people can make their eyes protrude out

00:26:31 of their sockets.

00:26:33 Unfortunately, this ability comes with downsides.

00:26:36 It can cause numerous eye issues.

00:26:38 Some indigenous groups of people, like Tibetans, can survive at altitudes as high as Mount

00:26:43 Everest.

00:26:44 This rare ability most likely appeared after years of evolution.

00:26:48 The ancestors of modern Tibetans lived in high regions for thousands of years and developed

00:26:53 red blood cell adaptations, making it possible to survive with dangerously low levels of

00:26:58 oxygen.

00:26:59 The Bajau are sea nomads living in Southeast Asia.

00:27:03 These people have evolved an extra-large spleen, serving as a repository of oxygen-rich blood

00:27:09 cells.

00:27:10 Thanks to that, they can easily spend 5 to 10 minutes fishing underwater without coming

00:27:14 up for air even once.

00:27:17 About 14% of the population don't have a palmaris longus muscle.

00:27:22 It's actually a rudimentary part of the body, and the need for it disappeared in the

00:27:26 process of evolution.

00:27:28 So if you don't have this muscle, worry not.

00:27:31 Its absence doesn't affect the work of your forearm anyway.

00:27:35 About 5 to 37% of people don't have wisdom teeth from birth.

00:27:39 These teeth are not really needed anymore.

00:27:42 They were important for our ancestors since they helped to chew hard food like nuts, roots,

00:27:47 meat, and saltwater taffy.

00:27:49 I made that up.

00:27:51 But since most of the food we eat today is processed, wisdom teeth are now a mere atavism.

00:27:57 Most people have just one clockwise hair whorl, but 5 out of 100 people have a double crown.

00:28:04 And if both whorls are directed counterclockwise, this makes a person even more unique.

00:28:09 Some scientists think there's a genetic link between hair whorl direction and handedness.

00:28:14 A bit more than 8% of right-handed people have counterclockwise hair whorls, but in

00:28:19 the left-handed, this number grows up to 45%.

00:28:24 A man's brain gets older faster than a woman's.

00:28:27 As men age, they start complaining about memory problems and lack of concentration more and

00:28:32 more often.

00:28:33 At the same time, women don't have such acute problems with memory, but they feel depressed

00:28:38 more often.

00:28:39 Hmm, which one would you choose?

00:28:43 When someone is lying, their own nose gives them away.

00:28:46 Psychologists from the University of Granada have discovered that when a person tells a

00:28:51 lie, the temperature around their nose and in the inner corners of their eyes goes up.

00:28:56 This phenomenon got the name of, wait for it, the Pinocchio effect.

00:29:01 Japanese people have particular bacteria in their intestines.

00:29:05 These bacteria help them to digest sushi.

00:29:08 The Japanese have been eating raw seaweed for centuries.

00:29:11 Microorganisms dwelling on the surface of the seaweed got into their bodies and actively

00:29:16 developed.

00:29:17 Nowadays, the bacteria help Japanese people digest raw food and prevent different problems

00:29:22 connected with food.

00:29:25 So people have as many hairs on their bodies as chimpanzees.

00:29:29 The hair count of a person and a chimp is approximately the same.

00:29:33 The only difference is that human body hair is mostly useless and so fine that it's

00:29:38 almost impossible to see.

00:29:41 Humans don't have more genes than other species.

00:29:43 In fact, people have fewer genes than a worm.

00:29:46 Tomatoes also have many more genes than you do.

00:29:49 But we are such complicated creatures.

00:29:51 Well, recently, scientists have concluded that the number of genes that a genome contains

00:29:56 isn't closely connected with the complexity of a living being.

00:30:00 Let's take a breather.

00:30:02 Speaking of which, your left lung consists of two lobes, while your right lung is divided

00:30:07 into three parts.

00:30:08 Plus, the lung on the left is a bit smaller since it has to make room for your heart.

00:30:13 Your lungs also contain around 1,500 miles of airways.

00:30:17 It's more than half the distance between New York and Los Angeles.

00:30:21 There are also more than 300 million alveoli, which are tiny balloon-shaped air sacs in

00:30:26 your lungs.

00:30:28 People have 5 most obvious senses – vision, smell, touch, hearing, and taste.

00:30:34 But that's not all.

00:30:35 How about thermoception – the sense of heat?

00:30:38 Or nociception – the perception of pain?

00:30:41 Or your body awareness – proprioception?

00:30:44 To figure out what it is, close your eyes and touch your nose.

00:30:47 Got it?

00:30:48 That's proprioception in action.

00:30:50 This list can be much longer.

00:30:52 Some experts state people have from 21 to 53 senses.

00:30:57 So your fingers get all wrinkly after you spend too much time in the water.

00:31:01 Pruney fingers are caused by the narrowing of your blood vessels.

00:31:04 When you stay in the water for a long time, your nervous system makes your blood vessels

00:31:08 shrink.

00:31:09 Your body sends the blood away from that area.

00:31:12 And this loss of blood makes your vessels thinner.

00:31:14 The skin starts folding over them, forming those funny wrinkles.

00:31:18 Scientists think this process helps us have a better grip when our hands and feet are

00:31:22 wet.

00:31:23 There are 3 kinds of cone cells in the average person's eyes.

00:31:27 These cones help to recognize the colors in the blue, red, and green spectrums.

00:31:32 Thanks to them, most people can distinguish around 1 million different shades.

00:31:36 But those with tetrachromacy have 4 cones in their eyes.

00:31:40 This feature allows them to see up to 100 million different hues.

00:31:44 This vision anomaly is extremely rare, and is much more common in women than in men.

00:31:49 Interestingly, most people with tetrachromacy don't even realize they see the world brighter

00:31:54 than others.

00:31:56 Not all people have round pupils.

00:31:58 Two people out of every 10,000 have unusually shaped pupils.

00:32:03 Most commonly, they resemble keyholes.

00:32:05 This eye disorder is called Kolobova.

00:32:07 Interestingly, some people with this condition don't have any problems with their vision.

00:32:13 Only 3 to 22% of people in the world have Morton's toe.

00:32:18 It's a foot structure where the second toe is longer than the first one.

00:32:22 Michelangelo's David and the Statue of Liberty both have this unusual body feature.

00:32:27 Hey, toes up!

00:32:29 In some people, saliva accumulates in a gland under their tongue.

00:32:33 It can then get propelled out in a stream when a person presses on this gland.

00:32:38 If the mouth is open at the moment, a jet can reach several feet.

00:32:42 This process, called gleeking, can occur spontaneously.

00:32:45 A person accidentally pushes their tongue against the gland while eating, yawning, talking,

00:32:50 or cleaning their teeth, and voila!

00:32:53 Up to 35% of people can gleek, but just 1% can do it on command.

00:32:58 I had a friend in college who did that.

00:33:00 Yeah, it was weird.

00:33:02 About 18 to 35% of people have an interesting reaction to sunlight – they sneeze.

00:33:08 This phenomenon has its own name – the photic sneeze reflex.

00:33:12 In the Greek language, it's called sun sneezing.

00:33:17 Just like salamanders regrow their tails, humans might be able to regenerate cartilage.

00:33:22 That's the rubber-like stuff around your joints.

00:33:25 Recently, scientists have discovered that cartilage might be able to repair itself.

00:33:29 Most effectively at the ankle, not that well in the knee, and least effectively in the

00:33:34 hip.

00:33:36 The human brain is 73% water, just like your heart.

00:33:39 That's why if your brain loses even 2% of liquid, you start feeling exhausted.

00:33:45 This also makes your memory get worse, shortens your attention span, and puts a damper on

00:33:50 your mood.

00:33:51 So drink up!

00:33:53 Your brain is constantly processing tons of visual information – around 600 million

00:33:58 bits per minute.

00:33:59 It all starts when the light goes through the cornea, your eye's clear, protective

00:34:03 outer layer.

00:34:05 Then the light turns into electrical signals.

00:34:07 They travel to your brain, and it interprets them into the images you see.

00:34:11 It takes milliseconds for this complicated process to happen.

00:34:16 People who live to be 110 years and older, called supercentenarians, may have a secret.

00:34:22 Researchers have discovered that their immune cells, called teeth helpers, might change

00:34:26 and adapt to the late stages of aging.

00:34:29 These cells are likely to protect them from viruses and other health problems.

00:34:34 We've become impressive multitaskers, thanks to technology.

00:34:38 Or rather, it only seems so.

00:34:41 The human brain can't concentrate on two things at once.

00:34:44 What it can do is to switch between several tasks really fast.

00:34:49 But it makes your attention span shorter and harms your short-term memory and the ability

00:34:53 to learn.

00:34:54 So put that phone down!

00:34:57 So when a woman is pregnant, her brain goes through many changes that prepare her for

00:35:02 childbirth.

00:35:03 And the part of her brain that's responsible for social signals decreases.

00:35:08 This causes the brain to be more efficient at taking care of the baby.

00:35:11 But don't worry, it doesn't stay that way.

00:35:14 It returns to its standard size after the pregnancy.

00:35:18 In a day, your body produces 2 pints of saliva.

00:35:22 That's around 80 gallons a year.

00:35:25 And in one lifetime, yes, you can fill two Olympic pools with spit.

00:35:30 Imagine swimming in one, you!

00:35:32 That's disturbing and disgusting at the same time.

00:35:37 Humans have one secret superpower hidden in our stomachs – our stomach acid.

00:35:42 It has a pH of around 1, and it is one of the most acidic substances in the world.

00:35:47 It's so powerful that it can dissolve metals, and the stomach must develop special protective

00:35:52 mucus to prevent your whole body from dissolving.

00:35:55 But don't try to eat metals – they can be toxic.

00:36:00 If you take a big breath, your left lung will be filled with much less air than your right

00:36:05 one because it's smaller.

00:36:07 Your heart takes up quite a bit of space, so the left lung has to make room for it.

00:36:11 The lungs are divided into lobes.

00:36:13 The right has three, and the left lung has only two lobes.

00:36:17 Your lungs aren't the only organs that are not proportional in size.

00:36:22 Your kidneys are also a bit different.

00:36:24 The left one is typically a bit larger than the right one.

00:36:27 If you've ever wondered how big they are, your kidneys are the size of your fist.

00:36:33 Everyone knows that sharks have strong teeth, but the outer layer of our teeth, called enamel,

00:36:38 is as strong as the one covering sharks' teeth.

00:36:41 The enamel is also the strongest substance in the body.

00:36:44 It protects our teeth from all kinds of damage, so you can eat your favorite food in peace.

00:36:50 Like pizza!

00:36:54 Toenails grow twice as slowly as fingernails.

00:36:57 Or at half speed.

00:36:58 Whichever one you like.

00:36:59 And if there was an Olympic sport determining which nail grows the fastest, well, your pinky

00:37:04 nail would always come in last because it is the slowest-growing nail out of 'em all.

00:37:09 The reason for this is that some fingers aren't used as much as others and don't have as

00:37:13 much blood supply.

00:37:15 There are weird animals like shrimp and crabs that drop their skeletons in order to grow.

00:37:21 Don't be shocked to learn that we do the same thing.

00:37:24 We don't literally drop our skeleton, of course, but we slowly regenerate a new one every 10

00:37:29 years.

00:37:30 So in our whole life, we will change our skeleton around 8 times.

00:37:36 Many years ago, we were reptiles like the evil lizard from Spider-Man.

00:37:39 Luckily, we've evolved and lost almost all of our reptile features except the third vestigial

00:37:45 eyelid, which is partially visible at the end of your eye close to your nose.

00:37:50 Reptiles still have this.

00:37:52 It is used to protect and clean the eye.

00:37:56 If you have polychorea, your eye can develop more than one pupil.

00:38:00 Sadly, this won't improve your vision.

00:38:02 It can make it worse, in fact, but in most cases, it won't affect your vision much.

00:38:07 This condition is super rare and typically starts in childhood, but it can also develop

00:38:12 later in life.

00:38:14 Dermatographia is a usually harmless condition that allows you to virtually write on your

00:38:19 skin.

00:38:20 People who have this condition don't need notebooks to keep notes.

00:38:24 If you have this condition and you scratch your skin lightly, the redness can last for

00:38:28 half an hour.

00:38:30 This might be helpful at your next exam, if you know what I mean.

00:38:35 Another unique condition that some people have is syndactyly, or webbed toes.

00:38:40 This is when your toes are fused together.

00:38:42 Nobody knows what causes this, but it's nothing serious.

00:38:48 Did you know that your tongue is as unique as your fingerprints?

00:38:51 Yeah, me neither.

00:38:53 The tongue has special shapes and geometric figures, like fingerprints, that differ from

00:38:57 person to person.

00:38:59 Who knows, maybe we'll unlock our phones by licking them in the future.

00:39:03 Or not.

00:39:04 A fully grown person is made up of around 7 octillion atoms.

00:39:08 It sounds unreal, but it's true.

00:39:11 That number is so big that I can't even say it in one breath.

00:39:15 It's 7 followed by 27 zeros.

00:39:19 Earwax looks like wax, feels like wax, and tastes like… of course, I have no idea what

00:39:24 it tastes like, and please don't try to find out.

00:39:28 My point is, it's not actually wax.

00:39:30 It's a combination of fat, skin cells, dirt, and sweat.

00:39:35 It's important for the health of the ears because it helps keep them clean.

00:39:41 Pound for pound, bones are much stronger than steel.

00:39:44 The same density of bone will almost always outperform steel.

00:39:48 But if you compare the same volume of bone and steel, the bone will break before the

00:39:53 steel does.

00:39:54 Bones are made to be light and strong.

00:39:56 If they were made of steel, we'd be a lot heavier and would need much more energy to

00:40:00 move.

00:40:02 When you were born, you had more bones than you do now because most of them have fused

00:40:07 together.

00:40:08 An adult person has 206 bones, while babies have 300 bones.

00:40:13 Some of those bones are made of cartilage, which is flexible and soft.

00:40:18 The strongest, heaviest, and longest bone is the femur.

00:40:22 This bone is the most difficult to break.

00:40:24 It can take up to 30 times your body weight or around 6,000 pounds.

00:40:28 Technically, you could balance two cars on your femur and still be fine.

00:40:33 But don't try it.

00:40:36 Bioluminescence is a talent some animals have, like angelfish, fireflies, lanternfish, and

00:40:43 humans.

00:40:44 Yep, you actually shine in the dark.

00:40:47 Scientists have discovered that we glow, but the shine is 1,000 times weaker than what

00:40:51 our eyes can detect.

00:40:53 You can see yourself glow if you have an ultra-sensitive camera.

00:40:57 The amount of melanin you have in your eyes determines what color they are.

00:41:02 Brown eyes have the largest amount of melanin, and blue eyes have much less of it.

00:41:07 However, people with heterochromia have different color eyes.

00:41:11 One eye can be blue, and the other can be brown, or any other color, which is cool.

00:41:16 Sometimes only half the eye can be a different color.

00:41:20 When you sneeze, the air exiting your nose and mouth can travel at almost 100 mph.

00:41:27 We sneeze because some irritants enter the nose, and the body sneezes to remove it.

00:41:32 And if you've never heard about your eyes falling out if you sneeze without closing

00:41:35 them, that's a lie.

00:41:37 Nothing will happen.

00:41:40 Your heart is the only muscle that works 24 hours, 7 days a week.

00:41:45 It beats over 3 billion times in a person's life and pumps around 2,500 gallons of vital

00:41:51 fluid daily.

00:41:52 So you should take good care of it because it works super hard, and you can't do without

00:41:57 it.

00:41:58 Your funny bone isn't actually a bone but a nerve.

00:42:01 That's why when you hit it, you get the feeling that a thousand ants are crawling under your

00:42:05 skin.

00:42:06 This nerve is quite long.

00:42:07 It starts in the spine and ends in your pinky and ring fingers.

00:42:12 Almost all of us have heard that our noses and ears never stop growing.

00:42:15 Well, this is not really true.

00:42:18 Our noses and ears stop growing when we become teenagers.

00:42:21 But they do get bigger as we age because gravity is pulling them.

00:42:25 So they're actually stretching, not growing.

00:42:29 When you don't get enough sleep, the brain can literally start eating itself.

00:42:33 13% of neurons are destroyed when you don't get a good night's sleep.

00:42:37 That's a lot of brainpower to lose.

00:42:39 Instead of finishing that episode of your favorite series, "Go to bed!" it's not

00:42:44 worth it.

00:42:46 When you are well-rested and have enough sleep, your brain can create enough electricity to

00:42:50 power a lightbulb.

00:42:52 And your neurons can send more messages than all the phones in the world combined.

00:42:56 They travel at around 150 miles an hour, and the signals carried by your motor neurons

00:43:01 can travel twice as fast.

00:43:05 Unlike our primate pals, many people still have these foot arches.

00:43:10 They help us move.

00:43:12 This arch is like a built-in shock absorber for your feet.

00:43:15 It's what allows us to bounce.

00:43:18 There's another one.

00:43:19 It's called the transverse arch, running side to side on the top of your foot.

00:43:24 Think of it like a bridge that helps keep your foot in shape.

00:43:28 Research says this arch is a big deal, too.

00:43:31 It's responsible for about 40% of your foot's stiffness.

00:43:35 Simply put, it's like the scaffolding that holds your foot together.

00:43:39 When scientists snipped the transverse arch, the foot lost a lot of its firmness.

00:43:44 But when they cut the bottom arch, it wasn't that dramatic.

00:43:48 So is it a modern human thing?

00:43:51 Nope.

00:43:52 These arches didn't just pop up yesterday.

00:43:54 The transverse arch has been around for 3 million years.

00:43:58 The bottom arch showed up about 1.8 million years ago.

00:44:03 We might as well continue with another element of our feet before moving up to other parts.

00:44:09 Our pinky toes are also more important than they seem.

00:44:12 Whether you were born without one or have lost it, you can still walk.

00:44:16 But pinky ones are important for keeping us on our feet.

00:44:20 They provide balance.

00:44:22 Inside your foot, you've got 26 bones that team up to make sure you don't topple over.

00:44:27 Small toe is a part of this balance work.

00:44:30 Our ape ancestors needed their toes to grab, claw, and swing from trees.

00:44:35 Today we've traded our tree climbing skills for comfy couches and binge watches.

00:44:40 Okay, let's move up a bit and talk about the appendix.

00:44:44 You might think that it's useless, but nope.

00:44:47 When a human is in their mommy's belly, this organ starts to do its job.

00:44:52 Around the 11th week of development, it starts churning out special cells that produce helpful

00:44:57 hormones and compounds.

00:45:00 The appendix helps train our immune system's troops ensuring they're top-notch defenders.

00:45:05 It also collects all sorts of foreign substances, aka antigens, from our digestive tract.

00:45:11 Yet, as diets evolved, this piece shrank like a deflating balloon.

00:45:17 Unlike most other vestigial structures, the appendix isn't always harmless.

00:45:23 It can turn into an angry little fireball.

00:45:26 By the way, vestigial organs are the ones that have lost their primary ancestral function.

00:45:33 These structures mostly lack an apparent purpose.

00:45:36 Another famous vestigial example is wisdom teeth.

00:45:39 Those are pointless and have been causing us trouble for ages.

00:45:43 Yet nearly 95% of us have them.

00:45:46 And 90% might even have to deal with the drama of an impacted wisdom tooth at some point.

00:45:51 If you don't have them, you might consider yourself lucky.

00:45:54 Here's an additional interesting fact about wisdom teeth.

00:45:58 Even though your teeth have a mineral softer than what's in shark teeth, new tests show

00:46:03 that they're just as resilient.

00:46:05 The coating on shark teeth is actually similar in hardness to the enamel on a human wisdom

00:46:10 tooth.

00:46:11 It's because their surfaces are made of mineral crystals held together by proteins.

00:46:16 These prevent them from shattering easily upon impact.

00:46:20 So the difference in how we and sharks use our teeth comes down to their design, not

00:46:24 their toughness.

00:46:26 Anthropologists have examined ancient skeletons.

00:46:30 They think our ancestors needed these extra teeth to chew tough stuff, like roots and

00:46:34 raw meat.

00:46:36 Back then, those extra teeth came in handy.

00:46:40 But then we discovered cooking, and suddenly our food got softer, and our jaws got smaller.

00:46:47 Geneticists have their own take on this subject.

00:46:50 It involves a gene called MYH16, which seems to play a role in both brain size and jaw

00:46:57 characteristics.

00:46:58 Yet, the exact part it played in our evolutionary story is still a bit of a mystery.

00:47:04 Now another pointless thing is the eyelid.

00:47:07 Well, not the regular eyelid.

00:47:10 You know, that little pink thing hiding in the corner of your eye.

00:47:14 Birds and some other furry pals use it to fend off dust and debris trying to mess with

00:47:19 their eyes.

00:47:21 But in us humans, it's mostly vestigial.

00:47:25 Meet the Palmaris longus.

00:47:27 About 85% of us still carry it around.

00:47:31 Maybe you also have it.

00:47:33 You can test it by putting your hand on a flat surface and making your pinky and thumb

00:47:38 meet.

00:47:39 If you spot a little tendon band doing the limbo in the middle of your wrist, then you've

00:47:43 found it.

00:47:44 It was there for gripping stuff and swinging around like Tarzan.

00:47:49 We can carry on with the grasping trick.

00:47:52 Even before you're born, around 16 weeks into your time inside your mom's tummy, you're

00:47:58 already practicing your grip.

00:48:00 You start by grabbing onto the umbilical cord.

00:48:03 When you finally arrive in the world, this reflex helps you hold onto things.

00:48:08 Fun fact, small monkeys can hang on one hand for ages, thanks to a similar trick.

00:48:14 Yet, we humans lose this super grip when we're around 3 months old.

00:48:20 When you're still in your mother's womb, you also have a mini tail.

00:48:24 But as you grow, it disappears, and those tiny vertebrae become your tailbone or coccyx.

00:48:31 Humans and our ape cousins don't have tails like other animals.

00:48:35 Our ears too have vestigial muscles.

00:48:39 They help animals hear better and express their feelings.

00:48:43 But in humans, these ear muscles don't do much.

00:48:47 We've figured out other ways to listen and show our emotions.

00:48:51 Yet some of us can still wiggle our ears with practice.

00:48:55 Surprisingly, toenails also count as a vestigial thing.

00:48:59 I mean, they function as the initial line of defense.

00:49:03 They protect the body against harmful microorganisms.

00:49:07 In our evolutionary journey, we used our fingernails and toenails for defense, digging, and climbing.

00:49:13 In the modern world, fingernails still come to our rescue, whether it's for peeling fruit

00:49:18 or that sweet sensation of scratching an itch.

00:49:21 Yet, toenails have retired.

00:49:23 But hey, we can apply nail polish to them.

00:49:26 For fashion's sake, they certainly work for many people.

00:49:30 It's not just humans who have useless limbs or organs.

00:49:34 In 1798, an anatomist examined a peculiar bird incapable of flying.

00:49:40 He documented his observations.

00:49:43 This avian species was none other than an ostrich.

00:49:47 Ostriches and cassowaries are just a few examples of birds possessing vestigial wings.

00:49:53 Anatomically speaking, these are rudimentary wings, incapable of granting flight to these

00:49:58 hefty creatures.

00:50:00 Yet, they aren't entirely devoid of function.

00:50:03 They serve the purpose of maintaining balance during rapid running.

00:50:07 Plus, they elaborate courtship displays, helping birds attract potential mates.

00:50:12 Now, when it comes to animals, a lot of them glow, too.

00:50:16 Around 76% of ocean animals, including jellyfish, worms, sharks, and sea stars, are bioluminescent.

00:50:23 They have a compound called luciferin that reacts with oxygen to create light.

00:50:28 And for them, it serves such purposes as stunning predators, attracting prey, or warning others

00:50:34 of danger.

00:50:36 We humans can glow, too.

00:50:38 Unfortunately, this glow is super faint.

00:50:41 Our eyes can't see it.

00:50:43 Our bodies emit light, but it's about a thousand times dimmer than what our eyes can detect.

00:50:50 Scientists found that our glow changes throughout the day.

00:50:53 It's the faintest in the morning and the brightest in the late afternoon.

00:50:57 Our faces glow more than the rest of our bodies.

00:51:00 They think it's because our faces get more sun exposure and have melanin, which has components

00:51:05 that can boost light production.

00:51:07 Some body tricks distinguish us from the rest of the animal kingdom.

00:51:11 For instance, do you know that humans are the only animals capable of blushing?

00:51:16 It seems we've got the exclusive rights to this rosy-cheeked phenomenon.

00:51:21 When we find ourselves in an embarrassing situation, our blood vessels dilate.

00:51:28 That's what gives us those blushes.

00:51:31 Embarrassment is a pretty complex emotion.

00:51:34 It's all about understanding what others think of us.

00:51:37 This might be too advanced for other animals.

00:51:40 Interestingly, bald uakari monkeys can also blush, but not in the same sense.

00:51:47 For them, this is a show of their good health.

00:51:50 Speaking of good health, we should honor our gut.

00:51:54 Your gut includes the stomach, liver, and more.

00:51:57 It's often called the second brain.

00:52:00 This second brain has its own nervous system.

00:52:04 It has 100 million messengers.

00:52:06 They send info to the rest of your body.

00:52:08 Even if the gut-brain connection is cut, it keeps working.

00:52:12 It ensures your digestive system functions on its own.

00:52:19 The human body is this perfectly balanced machine, right?

00:52:22 Well, not when I'm using it.

00:52:24 Normally, all its parts work seamlessly together to keep us thriving and, well, alive.

00:52:31 Each of our organs is essential for our day-to-day activities.

00:52:34 From breathing, walking, talking, and coming up with bright ideas that push humanity forward.

00:52:41 But are they really essential?

00:52:43 Do we really need all those body parts?

00:52:45 Or are some of them just ancient relics that we just got stuck with in this weird game

00:52:50 of evolution?

00:52:52 Take wisdom teeth, for example.

00:52:54 Nah, somebody already took mine.

00:52:56 Yep, they're those pairs of teeth stuck in the back of your mouth you often have to

00:53:00 go to the dentist for.

00:53:02 They're also known as third molars, and while they can be used to chew food, a lot

00:53:07 of people think they're just unnecessary.

00:53:10 And get this – around 22% of people worldwide don't even have all four of them.

00:53:16 When they do grow in, they're the most likely to become impacted, which means they get stuck

00:53:21 in the jawbone sideways and can't properly come through the gums.

00:53:25 It's all because our jaws are often too small to accommodate these extra guys.

00:53:30 Some smart scientists think that's because we've evolved to have smaller jaws over time.

00:53:36 Recent evidence also shows that what we eat as kids might also be to blame, but it's

00:53:41 hard to know for sure.

00:53:43 Apparently, munching on hard-to-chew foods like raw veggies and nuts can actually stimulate

00:53:48 jaw growth, while eating soft processed foods can kinda stunt it.

00:53:53 And that leaves little space for our back teeth to come in and, you know, do their thing.

00:53:58 Will they disappear altogether in the future?

00:54:00 I guess we human mammals will just have to wait and see.

00:54:04 Now let's talk about the vomeronasal organ, or as I like to call it, the nose's secret

00:54:10 instrument.

00:54:11 You see, rodents and other mammals have this awesome ability to communicate with each other

00:54:16 using chemical signals called pheromones.

00:54:19 And guess what?

00:54:20 They have a special organ called the vomeronasal organ, or VNO, that helps them detect these

00:54:26 pheromones.

00:54:27 Here's where it gets interesting.

00:54:29 While most adult humans have something resembling a VNO in their nose, it turns out that it's

00:54:35 basically a useless remnant.

00:54:38 Neuroscientists even say that if you look at the anatomy of this organ, you won't

00:54:42 see any cells that resemble those of similar organs from other mammals.

00:54:47 Also this organ in humans doesn't seem to be communicating with the brain either.

00:54:52 Now it's not all bad news.

00:54:54 Even though the human VNO is pretty useless, it looks like it still might respond to some

00:54:59 pheromones.

00:55:00 Will humans keep this organ on their evolutionary to-do list?

00:55:04 For now, I'd place it in the maybe pile.

00:55:08 Now here's a tail.

00:55:10 Animals that feature tails need these structures for a lot of things.

00:55:14 Some need it for balance, others for navigation, while some need it to attract potential partners.

00:55:21 But did you know that when we're just a few weeks old in our mother's belly, we

00:55:24 actually have tails too?

00:55:26 That's right, we have a whole little tail complete with vertebrae.

00:55:31 As we develop, that tail magically disappears and we're left with our trusty tail bone.

00:55:37 Humans and apes are unique in that we don't have tails, unlike other primates.

00:55:42 It's a mystery why apes lost their tails, but we can all agree that it makes us stand

00:55:47 out in a crowd.

00:55:49 However, once in a blue moon, a human is born with a little vestigial tail.

00:55:54 Cute, right?

00:55:55 Well, don't get too excited, because these tails don't have vertebrae and can sometimes

00:56:00 be associated with a tricky condition of the spine.

00:56:04 Either way, these tails are usually harmless and can be easily removed with a quick surgery.

00:56:10 And let's be honest, it's not like we're going to miss it.

00:56:13 After all, who needs a tail when you have arms and legs to get around?

00:56:18 Plus, can you imagine trying to find pants that fit with a tail sticking out the back?

00:56:23 Not a good look.

00:56:24 There's little to no chance humans will end up needing tails in the future, so I'm

00:56:29 guessing the tail bones are bye-bye in future generations.

00:56:33 Humans also have a funny little fold of membrane in the inner corner of the eyes, called the

00:56:39 plica semilunaris.

00:56:40 It's basically what's left of a third eyelid, which is still found in some animals, like

00:56:46 gorillas and other primates.

00:56:48 But here's the funny thing.

00:56:50 Even our close relatives, the chimpanzees, have this little fold that appears to be useless

00:56:55 too.

00:56:56 So we're not alone in this eye-quirkiness.

00:57:00 Speaking of unusual membranes, they serve a variety of functions in different animals,

00:57:05 such as protecting the eye from dirt and moisture, or hiding the iris from predators.

00:57:11 Some species can even see through their transparent membranes when they're underwater or under

00:57:16 ground.

00:57:17 Now, the reasons why we humans lost our third eyelid is still a bit of a mystery.

00:57:22 Maybe changes in our habitat and eye physiology made it unnecessary, or maybe we just evolved

00:57:28 to be too cool for a third eyelid.

00:57:31 Who knows?

00:57:32 With or without vestigial organs, it's interesting to imagine what humans might look like in

00:57:38 the future.

00:57:39 Many organs have become obsolete because of our lifestyle changes.

00:57:43 Care to have a peek into what we might look like in the future?

00:57:47 And in the same vein, or artery, have you heard of the concept of "tech's claw"?

00:57:51 It's where you spend so much time typing on your phone or laptop that your hand starts

00:57:56 to cramp up like a claw.

00:57:58 And that's just one of the physical changes that could happen to us if we don't take

00:58:02 care of our bodies in this tech-heavy world.

00:58:06 But it's not just our hands that are affected.

00:58:09 We could end up with 90-degree elbows from constantly holding our devices at that angle,

00:58:14 and even a smaller brain from all the distractions and information overload.

00:58:19 Now I know what you're thinking, "We just can't give up technology and go back to the

00:58:23 Stone Age!"

00:58:24 And you're right, we don't have to.

00:58:26 But we do need to be aware of the potential negative effects and take steps to reduce

00:58:31 their damage.

00:58:32 That's why a team of designers put their creative efforts together to present Mindy,

00:58:38 a future human whose body has physically changed due to the constant and never-ending use of

00:58:43 smartphones, laptops, and other types of maniacal devices.

00:58:48 While Mindy's exaggerated changes may not be in our future, the concerns behind them

00:58:53 are real.

00:58:54 So what can we do?

00:58:56 Well, one suggestion is to take regular breaks from our screens and stretch our legs a little.

00:59:02 Maybe even encourage some office yoga or dance parties to get the blood flowing.

00:59:06 We don't have to give up technology completely, but we do need to be mindful of its effects

00:59:12 on our bodies and minds.

00:59:14 Many years in the future, we might even get smaller in size.

00:59:18 One scientist reckons that if we were smaller, our bodies would need less energy, which would

00:59:23 come in super handy in our increasingly crowded planet.

00:59:27 It's funny to think about how different our lives are now compared to when we were hunter-gatherers.

00:59:33 Back then, we only had to interact with a handful of people each day.

00:59:38 But now, remembering people's names is a super important trait, and it might even be

00:59:43 something we grow to become better at.

00:59:46 Or technology might actually play a role in our evolution.

00:59:50 Scientists believe that we could one day have implants in our brains that help us remember

00:59:55 people's names.

00:59:56 It's like having a biological phone book directly in your body.

00:59:59 Wouldn't that be cool?

01:00:01 Maybe, who knows, maybe in the future, we'll even have visible technology as part of our

01:00:06 appearance.

01:00:07 Imagine having an artificial eye that can see different colors and visuals.

01:00:12 And don't even get me started on what we might look like if we colonized Mars.

01:00:17 With the lower gravity, our bodies could change in all sorts of ways.

01:00:21 We might have longer arms and legs, or even insulating body hair like our Neanderthal

01:00:27 ancestors.

01:00:28 It's hard to pinpoint what we might look like in the future without very precise data

01:00:33 to back the models up.

01:00:35 But it's fair to say these changes will be interesting, to say the least.

01:00:39 As for me, well, it's too late to say the least.

01:00:41 I've said over 1400 words here already.

01:00:50 The human tongue consists of eight intertwined muscles.

01:00:54 The whole structure resembles an elephant's trunk or an octopus' tentacle.

01:00:59 Just like them, the tongues are very flexible and can move in any directions.

01:01:04 People who live to be 1010 years and older, also called supercentenarians, may have a

01:01:10 secret.

01:01:11 Researchers have discovered they have more immune cells called T-helpers than the average

01:01:16 person.

01:01:17 These cells are likely to protect some people from some health problems.

01:01:23 Scientists have always thought that the human brain is a sterile place, free of germs or

01:01:28 bacteria.

01:01:29 But the latest studies have shown that experts might have been wrong all along.

01:01:34 It seems there are harmless microbes living in our brains.

01:01:38 But researchers need a bit more time to make sure.

01:01:42 Researchers believe that if people suddenly started to be born with six fingers, the brain

01:01:47 would easily adapt to it.

01:01:50 Those with polydactyly, extra fingers or toes, usually don't have any problems with this

01:01:55 feature.

01:01:57 Their brains know how to control additional fingers and how to use each of them independently.

01:02:03 Such people sometimes need only one hand to carry out a task, for which others would need

01:02:08 two hands.

01:02:10 In some people, saliva accumulates in a gland under their tongue.

01:02:15 It can then get propelled out in a stream when a person presses on this gland.

01:02:20 If the mouth is open at the moment, a jet can reach several feet.

01:02:24 This process, called "glicking", can occur spontaneously.

01:02:28 A person accidentally pushes their tongue against the gland while eating, yawning, talking

01:02:34 or cleaning their teeth.

01:02:36 And voila!

01:02:37 Up to 35% of people can glick, but just 1% can do it on command.

01:02:45 About 25% of people have an interesting reaction to sunlight, I mean sneezing.

01:02:51 This phenomenon has its own name - the photic sneeze reflex.

01:02:56 In the Greek language, it's called "sun sneezing".

01:03:00 Just like salamanders regrow their tails, humans might be able to regenerate cartilage,

01:03:06 that's rubber-like stuff around your joints.

01:03:10 Scientists have discovered that cartilage is likely to repair itself, most effectively

01:03:15 at the ankle, not that well in the knee, and least effectively in the hip.

01:03:20 The older you get, the fewer bones you have.

01:03:24 When people are born, they have many more than 206 bones.

01:03:28 In babies, most bones look different than they do in grown-ups, and there are more than

01:03:33 300 of them.

01:03:35 Where do those extra ones go?

01:03:37 They sure do not disappear or dissolve.

01:03:39 They fuse together as they develop.

01:03:42 Till the merge, some bones contain neither collagen nor calcium, what we think is standard

01:03:47 bone material.

01:03:48 No, they start as flexible yet tough cartilage.

01:03:52 Later, the cartilage turns into sturdier bones, and some of the pieces come together.

01:03:59 For example, the skull initially consists of 44 different elements, but a grown-up skull

01:04:05 is made up of 22 bones.

01:04:08 Some bones don't fully form till our early to mid-twenties.

01:04:13 When someone's lying, their own nose gives them away.

01:04:17 Psychologists from the University of Granada discovered that when a person told a lie,

01:04:22 the temperature around their nose and the inner corners of the eyes went up.

01:04:26 This phenomenon was called the "Pinocchio effect".

01:04:31 Ancient Greeks had stories about fire-breathing creatures called chimeras.

01:04:36 They were a fearsome mixture of a god, lion and a snake.

01:04:40 In real life, chimeras are people who have two different sets of DNA.

01:04:45 Scientists have recorded no more than 100 cases of human chimerism.

01:04:52 Albinism is a rare feature to have.

01:04:54 People with albinism have very little to no melanin, a substance that produces pigmentation.

01:05:01 But if it's ocular albinism that's even more unique, this kind of albinism affects

01:05:06 only a person's eyes.

01:05:08 Experts don't have exact numbers, but they think between 1 person in 20,000 to 1 person

01:05:14 in 50,000 have ocular albinism.

01:05:19 Scientists have figured out that you might be good at hearing things thanks to a teeny

01:05:24 jello violin.

01:05:25 Inside your ear, there is a miniature assembly line of nerves, tissues, fibers and bones.

01:05:32 It turns vibrations into sounds.

01:05:35 And there is also a blob of jelly-like substance made up of 97% water.

01:05:41 Researchers believe that thanks to this jello, your ear can separate high frequencies from

01:05:46 lower ones.

01:05:49 Your brain is constantly processing tons of visual information, around 600 million bits

01:05:55 per minute.

01:05:57 It all starts when the light goes through the cornea, your eye's clear, protective

01:06:01 outer layer.

01:06:02 After several transformations, the light turns into electrical signals.

01:06:06 They travel to your brain, and it interprets them into images you see.

01:06:11 It takes milliseconds for this super complicated process to happen.

01:06:16 The human brain is 73% water, just like your heart.

01:06:20 That's why if your brain loses even 2% of liquid, you start feeling exhausted.

01:06:25 This also makes your memory worse, shortens your attention span and puts a dampener on

01:06:31 your mood.

01:06:33 Around 65% of the world's population have loop-shaped fingerprints.

01:06:38 In 30% of people, fingerprints are whorl-shaped.

01:06:42 And only 5% of people have arch-shaped fingerprints.

01:06:47 All these types are divided into smaller groups.

01:06:50 For example, there might be plain or tented arches, accidental whorls, or the peacock's

01:06:55 eye, and so on.

01:06:58 If you have a circular hair whorl on your head, it's likely to be clockwise.

01:07:04 Some scientists think there is a genetic link between hair whorl direction and handedness.

01:07:09 A bit more than 8% of right-handed people have counterclockwise hair whorls, but in

01:07:15 the left-handed this number grows up to 45%.

01:07:20 There are more than 650 skeletal muscles in your body.

01:07:25 They make up around 40% of your body weight.

01:07:28 Up to 85% of the heat your body produces comes from your muscles contracting.

01:07:33 At the same time, caterpillars have many more muscles than people.

01:07:37 Some species - up to 4000 of them.

01:07:40 And the grasshopper has 900.

01:07:45 Your brain can decide what sounds to focus on when you're in a loud place.

01:07:49 Thanks to this ability, you can shut out all other voices and concentrate on the person

01:07:54 you're listening to.

01:07:57 The Bajor is a group of nomadic people that live in the waters around the Philippines,

01:08:02 Indonesia and Malaysia.

01:08:04 Thanks to a rare DNA mutation, they can stay underwater for up to 13 minutes.

01:08:10 The Bajor people have evolved spleens that are way larger than average.

01:08:14 This feature provides them with a genetic advantage.

01:08:17 See no mats needed to hunt for fish or look for underwater stuff that can be used in crafts.

01:08:24 Human bones might be loaded with a network of tiny tunnels.

01:08:28 Scientists knew nothing about them until recently.

01:08:31 That's why it was unclear how blood cells, which are produced in our bones, could quickly

01:08:36 exit bones and get into the blood circulation.

01:08:40 But now the mystery may be finally solved.

01:08:43 If there are holes, there can also be capillaries - miniature blood vessels.

01:08:49 Some people have more than one row of eyelashes.

01:08:52 This phenomenon is a genetic mutation called dystichiasis.

01:08:56 A person with this condition has a second set of eyelashes growing behind the first.

01:09:01 All these thick, lush lashes sure look beautiful.

01:09:04 But they can also cause some discomfort.

01:09:07 Some hairs can start growing in the wrong direction, or in the place where an oil gland

01:09:12 is supposed to be.

01:09:14 It can cause irritation and tearing.

01:09:19 Why do your fingernails turn blue when you get cold?

01:09:23 For one thing, your fingers are rather far away from the rest of your body.

01:09:28 Just like your toes or the very tip of your nose.

01:09:31 Imagine a piece of tissue in the middle of your body.

01:09:34 It gets circulation from all sides - left and right, up and down.

01:09:38 But the ends of your fingers have just one option.

01:09:41 Blood can only flow from the hand down the fingers.

01:09:44 When it's cold, little blood vessels, aka capillaries, in your fingers narrow.

01:09:49 It prevents blood from flowing as freely as before.

01:09:53 When blood circulation slows down, the tips of your fingers and your fingernails don't

01:09:57 get enough oxygen-rich blood.

01:09:59 And the less oxygen your blood contains, the darker it becomes.

01:10:03 Its color is actually dark red, but we perceive it as blue.

01:10:09 The hippocampus is a part of your brain that helps you navigate in space.

01:10:13 You have two of them, each the size of a chestnut.

01:10:16 London cup drivers have bigger hippocampi than most other people.

01:10:21 Researchers are sure it's thanks to their regular mental workout.

01:10:24 It's not a gimmick to navigate 60,000 London streets.

01:10:41 I'm not talking about the tingling, jolting pain you can feel when you hit your elbow

01:11:02 against something.

01:11:03 Oh, that feels almost like your entire arm has been electrocuted!

01:11:07 It's not a feeling I would consider funny, but it comes from the funny bone.

01:11:12 The funny bone isn't actually a bone.

01:11:15 It's a nerve that starts in your spine, goes through your neck, through your elbow, and

01:11:20 through your fingers.

01:11:21 Its real name is the ulnar nerve.

01:11:23 It's one of the three primary nerves in your arm, and it provides sensation to the fingertips.

01:11:29 Your ulnar nerve is well-protected by muscle, fat, and bone.

01:11:33 But there's one spot at your elbow where this nerve is exposed, and that spot is…yeah,

01:11:38 the funny bone.

01:11:39 A different but real version of Achilles' story, huh?

01:11:43 Okay, so now you know why it hits so different when you bump your funny bone and why you

01:11:48 feel nothing when you pinch your elbow.

01:11:51 Now the next phenomenon is related to socially awkward moments.

01:11:54 Okay, maybe not entirely.

01:11:57 It might happen when your crush gives you a compliment.

01:11:59 I'm talking about blushing.

01:12:02 Now I'm not sure those butterflies in your stomach exist when you're in love.

01:12:07 But I'm sure of this – when you blush, your stomach lining also turns red.

01:12:11 Yeah, I've looked.

01:12:13 The stomach lining is the tissue that protects your stomach walls from the acid inside.

01:12:18 When you blush, it also turns red because blushing happens when the blood rises to the

01:12:23 surface of the skin.

01:12:24 This affects the stomach too.

01:12:26 Now this is a natural process, a physiological response to the change in your emotions.

01:12:32 Now since we're talking about the stomach, it might be a good time to mention that the

01:12:36 stomach fluid has the ability to melt a steel table.

01:12:40 Yep.

01:12:41 This means the acid would be able to digest your internal organs.

01:12:44 Luckily, the stomach lining prevents this from happening.

01:12:48 Number 3 is about letting you know that you can glow in the dark.

01:12:52 Now don't turn off the lights just yet, you can't see it with the unaided eye.

01:12:56 These visuals of glittering human bodies come from ultra-sensitive cameras.

01:13:01 Japanese scientists were the first to capture the images of human bioluminescence.

01:13:06 Only ultra-sensitive cameras can reveal that our bodies emit tiny amounts of light because

01:13:11 this light is a thousand times weaker than the human eye can detect.

01:13:15 Apparently, all living creatures produce a small amount of light thanks to the chemical

01:13:20 reactions in their cells.

01:13:22 Humans are newly added to this list.

01:13:25 The researchers had been photographing the upper bodies of the volunteers for several

01:13:29 days.

01:13:30 The results showed that the amount of emitted light followed a 24-hour cycle.

01:13:34 The glow is at its highest in late afternoon and lowest late at night.

01:13:39 Plus, the brightest light is emitted from the cheeks, forehead, and neck.

01:13:44 Interestingly, this does not correspond with the brightest areas caught by thermal cameras.

01:13:49 Did you know you're a little bit taller in the morning than you are later at night?

01:13:53 Yes, I've been measuring you.

01:13:55 Seriously.

01:13:56 This height difference is related to gravity.

01:13:59 Its force compresses the cartilage in your spine and knees when you stand up or sit down

01:14:04 throughout the day.

01:14:05 But when you're lying down, your spine decompresses and relaxes.

01:14:09 That's why when you wake up in the morning after resting in bed all night, you're taller.

01:14:15 The increase in height is not even above an inch, so don't bet on who is taller after

01:14:19 hearing this information.

01:14:21 Fun fact, astronauts returning from a mission are a few inches taller than they usually

01:14:26 are on Earth.

01:14:27 It's because of the lack of gravity on the International Space Station.

01:14:30 They don't remain that tall forever, though.

01:14:33 When they're on the Earth again, gravity gradually squeezes them back down to their

01:14:38 usual height.

01:14:39 Now, let's get back to the organ we've already spoken about – the skin.

01:14:43 Yes, the skin is an organ.

01:14:45 In fact, it's the largest organ in your body.

01:14:48 It contributes to about 15% of your body weight.

01:14:51 What else does this organ do, besides covering your body?

01:14:55 It performs vital functions.

01:14:57 For instance, it protects your body from external physical and biological harm.

01:15:01 Plus, it prevents excessive water loss.

01:15:04 Now I can't help wondering what other surprises the human body has in store for us.

01:15:09 But right now, let's move on to the animal planet.

01:15:13 Owls don't have eyeballs.

01:15:15 Instead, they have something called eye tubes.

01:15:18 Their rod-shaped eyes do not move in their sockets as our eyeballs do.

01:15:22 That's why owls would have to move their entire bodies to look around.

01:15:26 But moving their torsos would make some noise, and other animals would hear it.

01:15:31 So owls have evolved to have necks that can twist to around 270 degrees, and they move

01:15:37 super silently.

01:15:38 But why the concern?

01:15:40 Well, night vision requires large corneas to get as much light as possible.

01:15:45 This is the main reason why most nocturnal animals, such as the slow loris or tarsier,

01:15:50 have big eyes.

01:15:51 For owls, it works a little differently.

01:15:53 Since they have small heads, such large eyes wouldn't be able to fit inside.

01:15:58 Now, even though these creatures don't have eyeballs, they have three sets of eyelids.

01:16:03 One set is for blinking, one is for sleeping, and the last one is for keeping their eye

01:16:07 tubes clean.

01:16:09 So do the owls give a hoot about that?

01:16:11 Yes, yes they do.

01:16:13 Moving on from nocturnal animals to the ones you're more familiar with – meow!

01:16:18 Cats have an extra organ that allows them to taste scents in the air.

01:16:22 This organ is called Jacobson's organ or the vomeronasal organ.

01:16:27 Jacobson's organ is located inside the cat's nasal cavity and opens into the roof of the

01:16:32 mouth.

01:16:33 This organ can detect specific chemicals by using nerves that lead directly to the brain.

01:16:37 That's not a regular sniffing, though.

01:16:40 The odor receptors of Jacobson's organ aren't designed to catch ordinary smells.

01:16:45 They detect chemicals that have no odor at all.

01:16:48 In other words, cats can detect undetectable smells.

01:16:51 It's not just this – Jacobson's organ increases the sense of smell.

01:16:56 For instance, when kittens need to find their mother's milk, imagine there are two mother

01:17:01 cats and four kittens.

01:17:03 Kittens can distinguish their mother from the other grown-up cat with the help of their

01:17:07 sense of smell.

01:17:08 Now, when two people meet, they assess each other's body language.

01:17:12 Cats can usually do this by sniffing each other's heads.

01:17:15 This greeting releases pheromones that can tell a lot about one cat to the other.

01:17:20 Like what the other feline likes to eat or if they are healthy or not.

01:17:24 They can even evaluate whether the other cat is happy or moody – all thanks to Jacobson's

01:17:29 organ.

01:17:30 Now, another fact about cats – their nose has distinct ridges that look like a pattern.

01:17:36 Similar to our fingerprints, every cat has a unique nose print.

01:17:40 It can be used as a form of identification.

01:17:42 "Okay, cat, we can nail you for breaking the vase.

01:17:46 We have your nose prints all over it.

01:17:48 Now do you want to cut a deal?

01:17:49 Just tell us what you know about the dog and that chewed-up DVD."

01:17:54 Dog lovers, no, I didn't forget about you.

01:17:56 Here's a myth you've probably heard – dogs are colorblind.

01:18:00 But they aren't!

01:18:01 However, it is true that the color range they can detect is limited compared to the spectrum

01:18:07 humans can see.

01:18:08 Their color palette consists mostly of yellows, blues, and violets.

01:18:12 Our reds, greens, and oranges are not noticeable to them.

01:18:16 This one is about turtles.

01:18:18 These animals cannot leave their shells and get back whenever they want.

01:18:22 In fact, they are completely attached to their shells.

01:18:25 These shells grow with turtles, similar to the human skin.

01:18:29 A turtle's shell consists of 50 bones.

01:18:31 It also includes a skeleton with the spine and rib cage.

01:18:35 So they go on vacation with it.

01:18:38 It's kind of like an RV that you can't get rid of.

01:18:41 Hey, can you speak up?

01:18:43 I just ate an entire pizza!

01:18:45 That's because after eating a hearty meal, our hearing tends to be a bit less sharp.

01:18:50 During digestion, most of our bloodstream is directed toward the stomach, which takes

01:18:55 away a bit from all the other organs.

01:18:57 So next time you want to go listen to your favorite band at a live concert, make sure

01:19:02 to eat a lighter meal to keep your ears pitch perfect.

01:19:06 On top of our stomach and left kidney, we have a magical organ that can grow back if

01:19:11 we remove a part of it.

01:19:13 Our liver can regenerate itself by making new cells called heptocytes.

01:19:18 They begin to multiply once the liver is damaged.

01:19:21 The seriousness of that damage defines if it can regenerate completely and the amount

01:19:26 of time it takes to do so.

01:19:29 Ever wondered what's worse for your body – no sleep or no food?

01:19:34 Turns out the lack of sleep is more dangerous.

01:19:36 That's because if you don't rest, your body becomes exposed to a lot more risks.

01:19:43 After 24 hours without any shut-eye, you can start to have memory problems and find it

01:19:48 difficult to concentrate.

01:19:50 At just 17 hours without sleep, you start to feel tired and groggy, irritable, tense,

01:19:56 and more emotional.

01:19:57 "I need a nap."

01:19:59 Your pain receptors also become more sensitive, which means everything hurts a bit more than

01:20:04 it should.

01:20:05 Oh, and it also affects your hearing too.

01:20:09 On the other hand, you can be well into your 24-hour period with no food before your body

01:20:14 realizes you've stopped eating.

01:20:17 In the first 8 hours, you just keep digesting the last meals you had.

01:20:22 After those first hours, you start to use stored fats for energy.

01:20:26 Not eating for more than 24 hours means that your body will start eating away at its own

01:20:31 protein, which means you literally start to lose muscle.

01:20:36 Rainwater isn't always safe to drink.

01:20:38 It can sometimes hold harmful bacteria and viruses.

01:20:42 Also in heavily polluted locations, it may even meet other harmful materials.

01:20:48 Some communities out there do depend solely on rainwater as their primary source of hydration.

01:20:54 But does rainwater have any other health benefits?

01:20:57 Not really, according to current studies.

01:21:00 Some of those risky substances may be removed from rainwater if you boil it.

01:21:04 But it's best to stick to the safer side and only drink water from sources that are

01:21:09 100% safe for human consumption.

01:21:13 We produce sweat mostly to regulate our body temperature and for some added moisture, like

01:21:19 the one we need in the palms of our hands for a better grip.

01:21:22 But sweat doesn't just show up on our skin.

01:21:25 It comes out of around 5 million pores on our bodies.

01:21:29 We're literally stepping on a quarter of our bones each day.

01:21:33 We have just over 200 bones in our body, but about a quarter of those are in a very small

01:21:38 surprising area – our feet.

01:21:41 Since we have 26 bones in each foot, we end up with literally 52 in both.

01:21:48 Our eyes produce tears for many reasons, like protecting themselves from infection or clearing

01:21:53 up debris such as smoke and dust, or when your baby done you wrong.

01:21:58 But the number of tears we produce is quite surprising – up to 30 gallons per year!

01:22:03 That's almost enough to fill a bathtub!

01:22:06 Wow, that is heartbreaking!

01:22:08 Our blood pressure wakes up hours before we do.

01:22:12 That's because in the morning, the body produces a bunch of hormones like adrenaline

01:22:16 and noradrenaline.

01:22:17 They help give us the energy boost we need during our morning hours, but they also increase

01:22:23 our blood pressure, which is usually higher between 6 am and noon.

01:22:27 During the night, since we should technically sleep and perform no physical activity, our

01:22:32 blood pressure drops down by up to 20%.

01:22:36 Speaking of our vital fluid, our blood accounts for about 10% of our total body weight.

01:22:42 We tend to think of our body weight as being mostly made up of muscles, fat stores, and

01:22:46 bones.

01:22:47 But there's a lot more to it.

01:22:49 In a fit adult person, bones make up 15% of the total body weight.

01:22:55 About 40-45% is left to muscles, about 15% to fat deposits, and the rest are stuff like

01:23:02 skin, tendons, hair, and other yucky things.

01:23:04 Let's see, that adds up to… yep, 100%.

01:23:10 Your lungs aren't twins – they're siblings.

01:23:13 That's because they aren't the same size or shape.

01:23:16 Your right lung is bigger and tends to weigh more, and your heart is to blame for it since

01:23:21 your ticker tilts to the left a little bit.

01:23:24 This creates a small indentation in the left lung called the cardiac impression, which

01:23:29 is also what funny heart doctors do at comedy clubs.

01:23:33 The right lung may be bigger, but it's a bit shorter since it needs to make room for

01:23:38 the liver.

01:23:39 Doesn't your house have a liver room?

01:23:42 Many of your body measurements are quite symmetrical in surprising ways.

01:23:46 If you were to stretch out both of your arms, your wingspan, and measure it, it should show

01:23:51 how tall you are.

01:23:53 Based on these similar measurements, specialists can even produce theories about what ancient

01:23:58 humans used to look like.

01:24:00 Looks like we've evolved to be increasingly symmetrical to appear more attractive and

01:24:04 healthier to attract mates.

01:24:07 Or so, since we've evolved to also walk on two legs, our symmetrical features help

01:24:12 us to move around with the least amount of energy because it creates balance.

01:24:18 Humans aren't natural champions when it comes to the scent of smell, that's for

01:24:22 sure, but our noses can pick up about 1 trillion different scents.

01:24:28 Scientists are still performing research on this subject and believe the number may be

01:24:32 even higher.

01:24:34 Some dog breeds may be able to notice scents somewhere between 10,000 and 100,000 times

01:24:39 better than we do, but turns out the best nose in the animal kingdom may be attributed

01:24:45 to the elephant because of its staggering number and type of olfactory receptor genes

01:24:50 over 10,000 while humans and chimpanzees have less than 400.

01:24:57 We tend to look at our pinkies as our most delicate fingers, but we do have more power

01:25:02 in them than we think.

01:25:04 Turns out that should our pinky finger be lost or affected, the overall strength of

01:25:09 our grip may decrease by up to 33%.

01:25:14 The liquid in our stomach, made of hydrochloric acid, potassium chloride, and sodium chloride,

01:25:20 is way more powerful than any acidic food you can think of, like lemons, pineapples,

01:25:25 or tomatoes.

01:25:26 The pH of healthy stomach acid should be between 1 and 3, so if you think about it, it's

01:25:32 just below that of battery acid.

01:25:36 Our hair strands are strong too, so strong that research is performed on them to duplicate

01:25:42 their resistance into human-made materials.

01:25:45 A healthy head of hair should be able to withstand up to 26,000 pounds.

01:25:50 It's due to a little protein in the hair strand called keratin, which you can also

01:25:55 find in your nails and skin.

01:25:58 Only about one-third of us humans have perfect vision.

01:26:01 There are a lot more glasses and contacts out there than you'd think, making up about

01:26:06 66%.

01:26:07 Apart from different eye conditions, our vision also gets worse with age.

01:26:13 When we're born, our heads amount to one-quarter of our total length.

01:26:17 By the time we reach 25, our head will only be one-eighth of it.

01:26:21 That's because our heads won't change their size a lot as we grow older, as opposed to

01:26:26 the rest of our body, mostly when it comes to the legs and torso.

01:26:31 Our brains are these super-powerful computers, and a single human brain cell can hold five

01:26:36 times as much information as the entire Encyclopedia Britannica.

01:26:41 Maybe you remember that!

01:26:42 We've yet to pinpoint the exact amount of data it can support, but in electronic terms,

01:26:48 the storage capacity of the brain is around 2,500 terabytes.

01:26:54 For comparison, the National Archives of Britain, which keeps over 900 years of history, only

01:27:00 takes up 70 terabytes.

01:27:02 It's probably the reason our brains need the most amount of oxygen compared to other

01:27:07 organs.

01:27:08 About 20% of the total oxygen that enters the bloodstream, and that's despite the

01:27:13 fact that it makes up only 2% of our body mass.

01:27:17 Our normal activities, plus the effect of gravity, make the cartilage in our ankles,

01:27:22 knees, hips, back, and neck slowly compress.

01:27:26 Once you rest overnight, the cartilage goes back to normal.

01:27:30 On average, you are somewhere around 0.4 inches taller in the morning than you are later at

01:27:36 night.

01:27:37 And that's why they call me Stretch.

01:27:42 You have as much hair as a monkey.

01:27:44 Haha, I don't mean to be insulting, but your fingerprints are not unique.

01:27:49 You can hear better after you cover your ears.

01:27:52 Can these statements be true, or are they nothing but myths?

01:27:56 When a person is lying, their own nose can give them away.

01:28:00 Can it be true?

01:28:05 Yep.

01:28:09 Researchers from the University of Granada have discovered that when a person tells a

01:28:13 lie, the temperature around their nose and in the inner corners of their eyes rises.

01:28:19 This phenomenon got named the Pinocchio effect.

01:28:22 Hey, how about this one?

01:28:25 People can have as many hairs on their body as chimpanzees.

01:28:29 Can you believe this?

01:28:33 Surprisingly, this one's true too.

01:28:38 The hair count of a person and a chimp, or any other ape of our size, is approximately

01:28:44 the same.

01:28:45 The only difference is that human body hair is quite fine and often colorless.

01:28:50 This makes it hard to see the sheer number of hairs.

01:28:54 Your lungs are identical.

01:28:56 It sounds reasonable, but is it true?

01:29:01 Well, that's nothing but a myth.

01:29:07 Your left lung consists of two lobes, while your right lung is divided into three parts.

01:29:11 Plus, the lung on the left is a bit smaller.

01:29:14 It has to, to make room for your heart.

01:29:18 By the way, your lungs also contain around 1,500 miles of airways.

01:29:23 It's more than half the distance between New York and Los Angeles.

01:29:26 There are also more than 300 million alveoli, tiny balloon-shaped air sacs, in your lungs.

01:29:33 I bet you've heard this one before – carrots can make your eyesight better.

01:29:37 True or myth?

01:29:42 Unfortunately, this idea isn't true.

01:29:47 Neither can carrots get you better night-time vision.

01:29:51 Carrots are indeed packed with vitamin A. It benefits your body and protects your eyes.

01:29:56 But even these veggies can't save you from wearing glasses if you need them.

01:30:01 Some people sneeze when looking at the sun.

01:30:05 Now, do they?

01:30:10 Yes, that's true.

01:30:13 About 25% of people have an interesting reaction to sunlight – they sneeze.

01:30:18 This phenomenon even has its own name – the photic sneeze reflex.

01:30:25 Shaving body hair makes it grow darker and thicker.

01:30:27 Is it the truth?

01:30:31 Don't worry, that's just a myth.

01:30:37 It might look as if your body hair has changed in thickness, rate of growth, or even color

01:30:42 after getting shaved.

01:30:43 But it's just an illusion.

01:30:46 Shaving makes the tips of hair follicles blunt.

01:30:48 That's why they look rougher and darker than usual.

01:30:51 But once your hair grows in again, it'll start to look the same as it did before you

01:30:56 shaved it.

01:30:58 You have unique fingerprints.

01:30:59 Ah, this one must be true, right?

01:31:07 The problem with this statement is that scientists can't prove that each set of fingerprints

01:31:11 is absolutely unique.

01:31:14 It does seem to people, but it's impossible to check.

01:31:17 And while this is improbable, people with identical fingerprints can actually turn out

01:31:21 to be real.

01:31:23 People have more than 5 senses.

01:31:25 Is it an appealing myth or reality?

01:31:34 There are 5 most obvious senses – vision, smell, touch, hearing, and taste.

01:31:40 But how about thermoception – the sense of heat?

01:31:43 Gnoseoception – the perception of pain?

01:31:46 Or the perception of your body awareness?

01:31:48 Proprioception – close your eyes and touch your nose.

01:31:52 Got it?

01:31:53 That's proprioception and action.

01:31:55 This list can be much longer.

01:31:57 Some experts state people have from 21 to 53 senses.

01:32:02 Your fingers actually get pruney after you spend too much time in the water for your

01:32:06 safety.

01:32:07 Is it true?

01:32:08 What's your bet?

01:32:15 Scientists believe so, but first things first – pruney fingers are caused by narrowing

01:32:19 blood vessels.

01:32:21 When you stay in the water for a long time, your nervous system makes your blood vessels

01:32:25 shrink.

01:32:26 Your body sends the blood away from that area, and this loss of blood makes your vessels

01:32:30 thinner.

01:32:31 The skin starts folding over them, forming those funny wrinkles.

01:32:36 Scientists aren't 100% sure, but they think this process occurs to help you have a better

01:32:40 grip when your hands and feet are wet.

01:32:43 People only use 10% of their brains.

01:32:46 Oh, how I wish it was just a myth!

01:32:54 And it is!

01:32:55 Apparently, you use almost 100% of your brain every day.

01:33:00 This organ is active all the time, even when you're asleep.

01:33:03 When you're snoozing, your frontal cortex, which is responsible for higher-level thinking,

01:33:08 and the areas that help you sense your surroundings, are still doing their job.

01:33:14 For some people, the world is much brighter than for others.

01:33:17 Hmm, how come?

01:33:25 That's actually true!

01:33:26 There are 3 kinds of cone cells in the average person's eyes.

01:33:30 These cones help to recognize the colors in the blue, red, and green spectrums.

01:33:35 Thanks to them, most people can distinguish around 1 million different shades.

01:33:40 But those with technochromacy have 4 cones in their eyes.

01:33:44 This feature allows them to see up to 100 million different hues.

01:33:48 This vision anomaly is extremely rare, and women have it more often than men.

01:33:54 But do you know the funniest thing about this?

01:33:56 Most people with technochromacy don't even realize they see the world brighter than others.

01:34:02 Sometimes you can hear better after closing your ears.

01:34:05 Well, it seems counterproductive, but can it be true?

01:34:14 Indeed, if you're in a loud place, for example, in a club or at a concert, you should close

01:34:20 your ears to hear your friends better.

01:34:22 Push the tragus, which is the pointy skin-covered cartilage in front of your ear canal, into

01:34:27 your ear.

01:34:28 Then, turn this ear toward your friend.

01:34:31 Voila!

01:34:33 You can prevent yourself from sneezing.

01:34:35 That would be very convenient, but maybe it's just a myth.

01:34:42 It's true!

01:34:45 If you don't want to sneeze, press the skin on the bridge of your nose with your fingers.

01:34:50 When you do it, your brain receives an alarm signal.

01:34:53 It immediately puts the brakes on all other processes, including the sneezing reflex.

01:34:59 Okay, you're gonna finish these 5 episodes of your favorite series now and catch up on

01:35:04 sleep later, but can you?

01:35:10 Unfortunately, no.

01:35:15 You can try to catch up on sleep at the weekend or take lots of afternoon naps during the

01:35:19 week, but it won't help.

01:35:22 Your body doesn't work this way.

01:35:23 If you didn't have enough sleep the night before or went to bed really late, sleeping

01:35:29 until noon won't save the day.

01:35:31 Even worse, too much sleep will make you feel groggy.

01:35:36 Some people have more ribs than others.

01:35:38 Is it a myth?

01:35:43 Nah, it's true!

01:35:47 Most people have 12 pairs of ribs, which makes 24 in total.

01:35:51 But 1 in 200 people has an additional 25th rib.

01:35:55 It's called cervical and forms at the base of the neck above the collarbone.

01:35:59 It can grow on the left, right, or even both sides of the body.

01:36:04 Those people who have extra ribs most likely know nothing about this modification.

01:36:08 That's because an extra rib rarely forms completely and can look like a thin strand

01:36:13 of tissue.

01:36:14 In this case, you won't see it even on an X-ray.

01:36:18 You should wait for at least a half an hour after eating before you go swimming.

01:36:22 Well, it sounds reasonable, but is it true?

01:36:28 Ah, that's just a myth.

01:36:32 The general idea behind this claim is that eating a large meal makes your blood flow

01:36:36 towards your stomach to help with the digestion process.

01:36:40 At the same time, your muscles don't get enough blood, which leads to cramps.

01:36:44 In reality, swimming right after having eaten something isn't dangerous at all.

01:36:50 Your blood doesn't get diverted enough for it to cause any serious problems.

01:36:55 Some people's snores can get louder than a working kitchen appliance.

01:36:59 What do you think about this?

01:37:03 Well, on average, when a person snores, the sound doesn't get louder than 60 decibels,

01:37:12 which is as loud as a regular conversation.

01:37:14 But sometimes, the noise level can reach 80 decibels, and that's as loud as a working

01:37:19 food blender.

01:37:22 Not all people have round pupils.

01:37:24 Can it be true?

01:37:29 Yup.

01:37:33 Two people out of every 10,000 have an unusually shaped pupil.

01:37:38 Most commonly, it resembles a keyhole.

01:37:40 This eye disorder is called coloboma.

01:37:42 Interestingly, some people with this condition don't have any problems with their vision.

01:37:51 You may have this rare body feature already and not know about it since sometimes even

01:37:56 an x-ray can't spot it.

01:37:58 Most of us have 12 pairs of rib bones, which means we were born with 24 ribs.

01:38:04 There are some folks, though, that actually have 25 ribs.

01:38:08 Only 1 in 200 people have this rare extra feature, and it's called a cervical rib.

01:38:14 It generally appears above the first rib, right at the base of the neck and above the

01:38:19 collarbone.

01:38:20 It's nothing to worry about, though.

01:38:22 Most of the time, they're unnoticeable, and if ever painful, they can be safely removed.

01:38:29 Do you know how huskies can sometimes have their eyes in different colors?

01:38:33 Some people come equipped with this rare feature, too.

01:38:36 The medical term for it is heterochromia.

01:38:39 The name comes from the ancient Greek word "heteros," which translates to "different,"

01:38:44 and "chroma," which means "color."

01:38:47 People with this condition can either have complete, central, or partial heterochromia.

01:38:53 The complete type means that the person has two completely different colored eyes, say,

01:38:57 one brown and one green.

01:39:00 Two different colors in the same eye are what specialists call central heterochromia.

01:39:05 A person with a partial heterochromia has just a portion of their eye of a different

01:39:10 color.

01:39:11 You can either be born with this condition or get it, say, after an injury.

01:39:15 Still, it's extremely rare.

01:39:18 Less than 200,000 people are diagnosed with it in the US.

01:39:22 Either way, let's face it, it does look pretty cool!

01:39:27 Speaking of eye color, wanna try guessing what the rarest one is?

01:39:31 I'll spare you the Google search.

01:39:33 It's gray.

01:39:34 Blue eyes may have been your first thought, and they are indeed already pretty rare.

01:39:39 Only around 8 to 17% of the world's population have this eye color.

01:39:44 When it comes to gray eyes, though, they're even more special.

01:39:48 Less than 1% of people have them.

01:39:51 This rare body feature is caused by a lower level of melanin in the eyes' layers.

01:39:56 If you're interested in meeting someone with gray eyes, your best chance is in Eastern

01:40:00 and Northern Europe.

01:40:03 Even rarer eye colors are red or violet, but these can sometimes be the result of different

01:40:08 health conditions.

01:40:10 There are people out there who have the superpower of seeing 100 million different colors without

01:40:15 the help of any fancy gadgets.

01:40:18 We see colors thanks to some cells in our eyes named cones.

01:40:22 Most of us have three types of cones to help translate what we see into the colors that

01:40:27 our brain is able to understand.

01:40:29 However, specialists think that there's a small group of people called tetrachromats

01:40:35 who have four types of these cones.

01:40:37 So far, researchers have only been able to identify women with this condition.

01:40:43 That little teardrop-shaped ball hanging in the back of your neck, you know, the one that

01:40:47 helps with swallowing your food, is called a uvula.

01:40:51 The name comes from Latin and translates to "little grape."

01:40:55 Surprisingly enough, around 2% of people are born with a bifid uvula, which means that

01:41:01 this indispensable organ in them is either split or forked.

01:41:05 You sure can surprise others with this cool feature of yours at parties!

01:41:09 Joking aside though, people with this bifid uvula may sometimes have trouble eating, drinking,

01:41:15 and speaking.

01:41:16 They might also have issues with digesting food.

01:41:19 Their speech may also sound a bit unusual, but this depends on how much the uvula is

01:41:24 split.

01:41:25 This particular body feature might not be the perfect trait when going on vacation,

01:41:30 but it does allow people to do more with less sleep.

01:41:33 They say that famous people like Nikola Tesla, Margaret Thatcher, and Winston Churchill had

01:41:38 this super rare feature.

01:41:41 This gene, called the DEC2 gene, helps with regulating our circadian rhythms.

01:41:47 Those are the natural biological clocks that let us know when we should be sleeping or

01:41:52 eating by making us sleepy or hungry.

01:41:55 A person with this rare mutation can basically go through a normal sleep cycle in less time.

01:42:01 They can feel rested even if they slept for only 4-5 hours.

01:42:05 That's one superpower I definitely want to have!

01:42:09 How about a gene mutation that gives you superhero-like bones?

01:42:13 They're basically unbreakable.

01:42:15 It also makes your skin less prone to aging.

01:42:18 Yep, looks like with this feature you can walk away from accidents unharmed and even

01:42:22 withstand the flow of time.

01:42:25 Some other people out there come with a very attractive feature, but it can go unnoticed,

01:42:30 at least at first glance.

01:42:32 They have a little something called distichiasis, which basically means an extra row of eyelashes.

01:42:38 Just in case you're wondering about the medical aspects too, it results from a genetic mutation

01:42:43 of a certain gene.

01:42:45 As beautiful as it may sound, people with that extra eyelash layer can experience some

01:42:50 pretty unpleasant sensations in their eyes and, in some cases, even have problems with

01:42:55 their vision.

01:42:58 If spun glass hair doesn't ring a bell, know that it is in fact a condition you might

01:43:03 have.

01:43:04 I know it's pretty self-explanatory, but just FYI, it causes frizzy and dry hair.

01:43:11 It's basically so unmanageable that you literally can't comb it.

01:43:15 It also tends to grow out from the scalp in all directions.

01:43:19 As for coloring, it comes in either bright blonde or silver.

01:43:23 Most of us have hair strands that are cylindrical.

01:43:27 People with this condition have triangular or heart-shaped strands or even flat altogether.

01:43:33 It's extremely rare, with only 100 confirmed cases, but it does become more manageable

01:43:38 with age.

01:43:40 Most of us humans have evolved to have some specific traits depending on the area of the

01:43:44 globe that we live in.

01:43:45 But there is a group of people, specifically those that live in higher altitudes, that

01:43:51 developed some pretty cool traits.

01:43:53 Let me explain.

01:43:54 High altitude environments come with less oxygen.

01:43:58 Not only do these people survive in these locations, but they've adapted to actually

01:44:02 thrive out there.

01:44:04 For example, those living in the Andes Mountains of South America have red blood cells that

01:44:09 can carry much more oxygen.

01:44:12 That makes their overall circulatory system a lot more efficient.

01:44:16 People living in similar conditions in other parts of the world have also adapted in their

01:44:20 own way.

01:44:21 They're able to take more breaths, so that they can properly supply their bodies with

01:44:26 oxygen.

01:44:28 This one is very important when it comes to looks, but means little in terms of a person's

01:44:33 overall health.

01:44:34 I'm talking about poggebledism.

01:44:37 Those who have it lack melanocytes, those cells that produce hair pigment in some parts

01:44:43 of their hair.

01:44:44 It's most common above the forehead, in front of their hairline, but it can also appear

01:44:49 on the eyebrows or eyelashes.

01:44:52 Folks who have it are born with this condition and carry it throughout their entire lifetime.

01:44:57 If you really want to get rid of it, there's always hair dye available, but I personally

01:45:01 think it looks super cool.

01:45:05 We all know cilantro really isn't everyone's cup of tea.

01:45:08 I don't know about you, but it tastes like soap to me.

01:45:11 It turns out it's not actually a preference, but rather a gene that causes the plant to

01:45:16 have this vile taste instead.

01:45:19 A study performed on a group of about 30,000 people revealed that you can find a particular

01:45:24 gene variant in people who say that cilantro tastes soapy.

01:45:29 This gene has more to do with the odor of the plant than the taste itself.

01:45:33 If you're one of those people but really want to give cilantro a chance, either way,

01:45:38 there's a small trick you can try.

01:45:40 Or ask the people that cook the meals in your household.

01:45:43 You can always crush the herb before using it in dishes.

01:45:46 Why does that help?

01:45:47 Well, because with crushing, the chemicals that are responsible for the soapy taste are

01:45:52 broken down and are less likely to taste unpleasant.

01:45:57 Now nobody really knows why we need the appendix, but it's always at the back of the book.

01:46:03 Wait, wrong appendix.

01:46:05 Some researchers claim the human appendix helped our ancestors process the tree bark

01:46:09 and whatever they were eating at that time.

01:46:12 As we have a way more balanced diet now, the appendix can disappear from our bodies without

01:46:17 any consequences.

01:46:19 Another purposeless thing in our bodies is the wisdom teeth.

01:46:23 Yeah, they used to come in handy when dentists didn't exist, but now we can ideally make

01:46:27 do without them.

01:46:29 Your brain will grow by roughly 2% if you venture into space.

01:46:34 Under normal gravity, it's thought that fluid in the brain naturally moves downwards

01:46:38 when we stand upright.

01:46:40 But there is evidence that microgravity prevents this, resulting in fluid accumulation in the

01:46:46 brain and skull.

01:46:48 When you age, your brain is gradually reducing in size.

01:46:51 By age 75, it's much smaller than at age 30, and it starts shrinking at 40.

01:46:57 It happens to everyone, so you just have to go with it and keep your brain busy and nimble.

01:47:03 If you stare into your eyes in the mirror, you'll see a small pink circle settled in

01:47:08 the corner of your eye.

01:47:09 This is your third eyelid.

01:47:11 Useless for us, but valuable for animals, like birds, to keep dust and scattered debris

01:47:16 from getting into their eyes.

01:47:18 This might sound familiar to you if you've heard of natural selection.

01:47:22 In short, natural selection keeps body parts throughout generations, but some of them are

01:47:26 harmful so they're phased out in the next generation, and others then aren't staying,

01:47:31 just like the third eyelid.

01:47:34 Not only your brain shrinks as you get older, you too shrink dramatically.

01:47:38 The bones get more brittle, the backbone gets compressed.

01:47:42 It works vice versa too.

01:47:44 When you rest at night, your bones kinda relax too, so you wake up taller than when you went

01:47:49 to bed last night.

01:47:51 Our ears help us keep the balance, so hearing isn't their only duty.

01:47:55 Our vestibular system occupies the inner ear.

01:47:58 Canals in your inner ear contain fluid and tiny sensors that look somewhat like hairs,

01:48:04 helping you keep your balance.

01:48:06 As for hairs, only a few body parts aren't covered with them.

01:48:10 These are palms, the soles of the feet, and lips.

01:48:13 Hairs grow even in the belly button.

01:48:15 Their purpose is to catch lint.

01:48:17 Mine does a great job!

01:48:19 And not only lint, our belly buttons have an entire animal encyclopedia in them, with

01:48:24 a range of about 70 different bacteria.

01:48:28 Some of them can also be found in soil in Japan, and even some bacteria typical for

01:48:32 polar ice caps.

01:48:34 See, you have a whole naval expedition going on and didn't even know it!

01:48:40 Only about 43% of you is you.

01:48:42 You're over 50% tiny little creatures that mainly live in your gut and other body parts

01:48:48 without ever leaving it.

01:48:50 Still, even though your cells are fewer than microbial ones, there are, on average, about

01:48:55 100 trillion of them in you.

01:48:58 With this in mind, your genes are less than half of what you consist of.

01:49:02 If you take all the microbes dwelling within your body and count their genes, it'll be

01:49:07 anywhere from 2 to 20 million genes and their combinations.

01:49:11 If you sleep, and I recommend that you do, it doesn't mean all of your body sleeps.

01:49:17 In fact, sometimes your brain has to work even harder when you're asleep.

01:49:21 It needs to process tons of information, and reports usually take time.

01:49:26 One thing that indeed rests while you're sleeping is your nose.

01:49:30 You won't smell anything nasty in your sleep.

01:49:32 The thing is that your sense of smell deactivates at night.

01:49:36 If there's some terrible smell in your bedroom, you won't even be bothered.

01:49:41 Scientists used to believe we could distinguish around 10,000 smells.

01:49:45 Nope.

01:49:46 Recent research showed that people could indicate more than a trillion smells.

01:49:50 We also remember them better than anything else, and odors can even evoke some distant

01:49:56 memories.

01:49:57 Meanwhile, our strongest and most emotional memories are usually fake.

01:50:02 It's the way the central memory works.

01:50:04 It gives us the confidence to believe everything we remember is real, even though we should

01:50:08 be confident about fewer details.

01:50:12 You don't mind if I call you a mammal, do you?

01:50:14 Well, among us mammals, only humans can always walk on two hind limbs and keep that posture

01:50:20 for their entire lives.

01:50:22 You may want to say that kangaroos or gorillas move in the same way, but kangaroos use their

01:50:27 tail as a third leg, and gorillas use the help of their long arms to keep balance.

01:50:33 Your bones take part in metabolism too.

01:50:36 Since they mainly consist of calcium, when there's not enough of this element in your

01:50:39 blood, bones start shedding it into the bloodstream, balancing your body.

01:50:44 And vice versa, when there's too much calcium in your blood, it goes into the bones to be

01:50:49 stored for later.

01:50:51 Our height, shape of our body, and skin color depend a lot on where our ancestors used to

01:50:57 live.

01:50:58 But we can adapt to new conditions even within our lifespan.

01:51:01 For example, if you move from the plains to the mountains, you'll eventually develop

01:51:06 more red blood cells to compensate for the lack of oxygen.

01:51:10 And naturally, if you drive from a colder climate to a hotter and sunnier one, your

01:51:14 skin will change pigmentation slightly to adapt.

01:51:18 Our lifespan is programmed within our cells.

01:51:21 They constantly renew and divide, but they have a sort of internal timer that stops at

01:51:26 some point.

01:51:28 Some cells also stop reproducing sooner than others.

01:51:31 On average, cells cease dividing when we reach the age of 100.

01:51:35 If we find a way to trick ourselves into turning off the timer, we could potentially live forever.

01:51:41 But we'd be a huge mass of wrinkles by then.

01:51:45 Body fat acts as insulation material, energy reserve, and shock absorber.

01:51:51 Your body sends the most fat into your waist region because that's where your internal

01:51:55 organs are.

01:51:56 If something happens to you, this layer of fat might as well protect those organs from

01:52:01 serious damage.

01:52:03 Your skull isn't a single bone.

01:52:05 It consists of 22 different bones, many of which are fused to protect your brain.

01:52:10 The mandible, or the lower jaw, is the only skull bone that's only attached to your head

01:52:15 with connective tissues and muscles.

01:52:17 This is what makes it so mobile – you can move it in any direction you like.

01:52:22 And the smallest bone in your whole body is inside your ear.

01:52:25 It's called the stapes, and it's no larger than a grain of rice.

01:52:30 Some of the strongest muscles in your body aren't in your arms or legs – they're

01:52:34 in your head.

01:52:36 The masseter is the primary muscle responsible for chewing, and it needs to be the strongest

01:52:41 for you to eat normally.

01:52:43 And you know those muscles that allow you to move your ears?

01:52:46 Those are temporalis, located above your temples.

01:52:49 They also help you to chew your food.

01:52:51 We've got two really fast muscles – they control the eyelids' opening.

01:52:56 In fact, they're the fastest muscles in our body.

01:52:59 Eyes are fragile and need protection.

01:53:01 So when the reflex is triggered, these muscles shut the eyes within less than a tenth of

01:53:06 a second.

01:53:07 We recognize only purple-blue, green-yellow, and yellow-red colors.

01:53:12 Everything else is a combination of these three.

01:53:15 It's impossible to calculate how many of these combinations the human eye sees, because

01:53:20 every single person has slight vision differences, but it's about 1 million combinations on

01:53:25 average.

01:53:27 Your stomach has an impressive capacity, holding up to a half a gallon of liquids – a whole

01:53:32 large bottle of Coke!

01:53:34 It's pretty hard to estimate how much hard food you can squeeze into your stomach, since

01:53:38 the food is processed with your teeth before it gets down there.

01:53:42 There's not enough room for a whole turkey, but who knows, probably a good-sized chicken

01:53:47 might fit it.

01:53:48 And hey, like my grandmother said, there's always room for ice cream.

01:53:53 Now show me where your stomach with all that cola, chicken, and ice cream is.

01:53:58 If you're pointing at your tummy, nope, it's up there, hidden in between your ribs.

01:54:03 Your tummy is full of intestines.

01:54:05 Let's see how many rare body features you or your friends have.

01:54:11 Elf-like ears are pretty rare.

01:54:13 They are different because of the pointy part on the outside.

01:54:16 There's an additional cartilage fold in the middle area around the part we know as

01:54:21 the scapha.

01:54:23 Most people are right-handed, while about 10% of them are left-handed.

01:54:28 But there are those with no preference for using a left or right hand.

01:54:32 They can play guitar, use scissors, write, and perform all other activities with any

01:54:37 hand they want.

01:54:39 Only 1% of those can do it, and we know them as ambidextrous.

01:54:44 And if you can talk out of both sides of your mouth, you may have a future in politics.

01:54:49 Less than 1/3 of the population can flare the nostrils on command.

01:54:53 The muscle in charge of this is weak because we have nothing to use it for.

01:54:58 That's why most people can't do such things with their nostrils on command.

01:55:03 People that live in Nepal and Tibet have a specific gene that allows them to breathe

01:55:08 at such high altitudes.

01:55:10 Most people feel sick in such conditions, but they are unique because they can breathe

01:55:15 normally.

01:55:16 It's a super-athlete gene they have there.

01:55:19 You can trace it back to denosavans, a group that lived in the mountainous areas around

01:55:23 Asia around 40,000 years ago.

01:55:26 This gene brings them a higher level of oxygen-carrying hemoglobin.

01:55:30 That's why the body can distribute oxygen more efficiently, so, unlike us, they won't

01:55:36 feel oxygen-deprived when performing certain tasks at such altitudes.

01:55:42 Arcus salinus is also pretty rare.

01:55:44 It's a white or gray arc you can see above and below the outer region of the cornea.

01:55:49 In other words, the clear dome-like thing that covers the front part of your eye.

01:55:54 It's something common in older people.

01:55:56 This arc may become a complete ring around the iris, the colored portion of the eye.

01:56:03 Some people naturally don't need to sleep too much.

01:56:06 The majority of us cannot take a couple of nights of lost sleep without consequences.

01:56:11 But a small percentage out there has this special gene that allows them to get away

01:56:16 with sleeping 6 or even fewer hours, which is about 2 hours less than average.

01:56:21 From 1 to 3% of the population has this so-called clock gene.

01:56:26 They can be more productive because they don't feel tired as we do when we sleep less.

01:56:32 Leonardo da Vinci, Thomas Jefferson, and some other famous historical figures were some

01:56:37 of them.

01:56:39 Most people have 3 cones in their eyes, so we can see a broad color spectrum.

01:56:45 But some have a rare 4th cone.

01:56:47 We call them tetrachromas.

01:56:49 And because of this feature, they can see up to 100 million colors.

01:56:53 The rest of us average folks see about 1 million colors.

01:56:58 It's a rare body feature you can mostly find in women.

01:57:02 Have you heard of heterochromia?

01:57:04 It's a rare condition where people have eyes of different colors or different colored sections

01:57:09 in each eye.

01:57:11 Sometimes this condition can lead to differences in color in some other parts of the body like

01:57:15 hair or skin.

01:57:17 Or it can result in irises with two different hues.

01:57:22 Heterochromia is a condition that happens because, due to genetics, some people have

01:57:26 unevenly distributed melanin in their bodies.

01:57:29 And only 1% of the population has it.

01:57:34 Chimerism is a rare genetic condition where a person has two completely different sets

01:57:38 of DNA, which we call genomes, in their body.

01:57:42 One genome is predominant in one organ or generally one area of the person's body,

01:57:48 whereas the other is in other tissues or organs.

01:57:51 Even animals can have this condition.

01:57:54 Both animals and humans with chimerism can even have two different blood types in their

01:57:59 bodies simultaneously, and we may be talking about different amounts of each of those types.

01:58:06 It would be cool to have bones so dense almost nothing could break them.

01:58:10 Some people have them, thanks to an LRP5 gene mutation.

01:58:15 People with these "rock bones" have 8 times denser bones than most.

01:58:20 When someone says there's a thing called "golden blood," it's easy to imagine

01:58:24 small particles of blood running through some people's veins.

01:58:28 It's not quite like that, nor does it have a golden color.

01:58:31 It's called this way because we're talking about a pretty rare blood group only about

01:58:36 40 people in the world have.

01:58:39 These people don't have all Rh blood cell antigens, which, in simple terms, means anyone

01:58:44 who has another rare Rh group can have this type as donor blood, which is pretty helpful.

01:58:51 Hey, check this out!

01:58:53 It's something called a long palmar muscle, and it was way more important to our ancestors

01:58:58 than to us.

01:59:00 Some of them were pretty big fans of climbing trees, so they developed a specific muscle

01:59:04 and ligament to perform that through time.

01:59:07 And some people still have it even today.

01:59:10 To check if you have it, just put the back of the palm on a flat surface.

01:59:14 Now touch your thumb and pinky together and lift them slightly.

01:59:18 If you see your ligament popping out, yup, you have a long palmar muscle.

01:59:25 Some have photosneeze reflex, which is a special condition where people uncontrollably sneeze

01:59:31 in response to bright light.

01:59:33 So the sun makes 10-35% of people sneeze.

01:59:38 If you have a perfect pitch, you should know it's really not that common.

01:59:42 It's when someone is able to identify and tell different musical notes based on their

01:59:47 frequencies.

01:59:48 So if you hear a D sharp, you can tell it's a D sharp without too much guessing.

01:59:53 Fewer than 1 in 10,000 people say they can have a perfect pitch, and it's still not

01:59:58 sure if you get it naturally or if it's necessary to develop it at a very early age.

02:00:05 Because research showed you can develop a perfect pitch, it takes a lot of training

02:00:09 and consistency to immediately tell the key and notes of your favorite song.

02:00:16 Not many people have naturally blonde hair.

02:00:19 And red hair is even rarer – less than 2% of the population has it.

02:00:23 And 11% of the human race have naturally curly hair.

02:00:29 We all learned in school that the heart is leaned toward the left side of the chest.

02:00:34 But certain people have it on the right side.

02:00:37 It doesn't necessarily mean this condition would have some negative consequences, but

02:00:41 it can affect the rest of the organs.

02:00:45 And 22% of the human race has Morton's toe.

02:00:49 And Morton wants it back!

02:00:51 Just kidding!

02:00:52 Morton's toe is when your second toe is longer than the big one.

02:00:55 If you look carefully, you'll see the Statue of Liberty has Morton's toe.

02:01:01 Some have this tiny bump on the inside of the upper part of their ear.

02:01:05 It's known as Darwin's bump or Darwin's tubercle.

02:01:09 Some even believe people who have this little bump potentially sense voice tonality better.

02:01:16 Only 16% of people across the globe can produce a roaring noise in their heads.

02:01:22 They do it by using their jaw.

02:01:24 They control a tiny muscle in the jaw that prevents it from hearing certain noises like

02:01:28 chewing.

02:01:30 But when these people flex it, they can hear a roaring noise from inside.

02:01:36 About one-third of the population can gleek.

02:01:39 And just 1% can do it on command.

02:01:42 Not that useful, but still rare.

02:01:45 4% of people have Raynaud's syndrome.

02:01:48 This is when a part of your body, usually your fingers or toes, start to turn white

02:01:53 when exposed to low temperatures.

02:01:55 It's your body's overreaction to cold or distress.

02:02:01 Check your fingerprints.

02:02:02 Are they looped, whirled, or arched?

02:02:05 The first two types are more common, while just 5% of people have arched fingerprints.

02:02:11 Not many people have birthmarks – only 10% of them.

02:02:15 In most cases, birthmarks are oval and have a coffee-type color.

02:02:20 Dimples may seem like something common, but only a quarter of the world's population

02:02:24 have them.

02:02:25 You can have one or two dimples.

02:02:28 And they're something we inherit, so if your parents have it, mhm.

02:02:34 That's it for today!

02:02:35 So, hey, if you pacified your curiosity, then give the video a like and share it with your

02:02:40 friends!

02:02:41 Or, if you want more, just click on these videos and stay on the Bright Side!

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