Crazy Facts About The Human Body You Probably Didn’t Know

These'll make you think.

The inner workings of the human body are vast and mysterious. Just beneath the surface of the skin, our bodies are constantly performing remarkable functions. There’s always something new and interesting to learn about the hard-working human body, so we’ve put together a list of some of the most fascinating facts about our bodies, plus some shout-outs to their most amazing abilities.

The Tooth Is The Only Part Of The Human Body That Cannot Repair Itself

If you’ve ever watched over time as a flesh wound stitched itself back together, you know that the human body’s capacity to heal itself is remarkable. There is one exception to this cool, regenerative superpower, however: our teeth.

“Cells are what start the healing process in our bodies,” Janne Reseland, a professor of biomaterials at the University of Oslo, explained to Science Nordic. “And as tooth enamel consists of 90 percent minerals, there aren’t many proteins and cells there.”

Cells do exist at the roots of our teeth, which can provide a certain amount of repair, but not in the teeth themselves, which means that once an adult tooth is chipped, broken or removed, it won’t regenerate.

Photo by Pink Sherbet Photography

Women Have A Better Sense Of Smell Than Men

It’s long been known that women outperform men in their ability to identify odors and scents and, in 2014, researchers found evidence to suggest that female superiority in this realm is actually based in biology. The study measured the number of cells in the olfactory bulbs of the brains of men and women, ultimately finding that women had an average of 43 percent more cells than men in this section of the brain, indicating a greater sensitivity to smells.

Evolutionarily speaking, the sensitivity might have originally developed to help women choose reproductive mates — before there was an app for that.


Your Fingertips Could Support The Weight Of Your Body

You may be surprised to discover that there are no muscles in the fingers that control movement or exhibit strength. The fingers are controlled by tendons, like puppet strings on marionettes. Still, fingers are incredibly strong and the tips of your fingers are even capable of supporting the weight of your entire body.

If you ever doubt the power of human fingertips, just watch a climber carefully scale a rock facade, often supporting their whole body with just the tips of their fingers.


Children Grow Faster In The Summertime

Although there doesn’t seem to be a concrete scientific reason for it, children typically grow fastest during the summer and slowest during the fall. The human growth hormone, a chemical that produces growth spurts in humans, is released primarily during sleep, so the summertime growth may have to do with kids getting more shut-eye over those holiday months when school’s not in session.


The Eye’s Muscles Move More Than 100,000 Times A Day

In other words, we move our eyes three times per second. That’s a lot of exercise! You might think this would result in constantly blurred vision but, according to psychologists, the brain works hard to regulate what we see.


After Bone Marrow, Hair Is The Fastest-Growing Tissue In The Body

The marrow inside our bones is the fastest-growing tissue in the human body, and the next-fastest is the hair on our heads. Even so, over the course of a year, we only grow about six inches of hair — total.

So while it’s the second-fastest-growing tissue in the human body, it still might feel like it takes a lifetime to grow it out — especially after you accidentally get baby bangs at the hairdresser.


Humans Are The Only Animals To Cry Emotional Tears

The phrase “crocodile tears” means a display of fake or insincere tearfulness, which makes sense, as crocodiles really don’t cry tears of sadness. In fact, no animal besides humans cries tears for sentimental reasons, even though all land animals are capable of producing tears to lubricate their eyes, and most mammals will make a call of distress when they are disturbed.


Babies Have 300 Bones, While Adults Have Only 206

It may be hard to believe, but the body of a tiny baby contains approximately 300 separate bones and cartilage elements at birth. However, nearly 100 of those bones are joined by membranes and will eventually fuse together, bringing the grand total of bones in an adult’s body down to 206.


Humans And Giraffes Have The Same Number Of Neck Bones

Humans and giraffes have a most interesting attribute in common. Our necks contain the same number of bones! Yes, that’s right. The hilariously long neck of a giraffe boasts the same amount of hardware as your own short, stout neck. Both humans and giraffes have seven neck vertebrae — but for a giraffe, each vertebra can be over 10 inches long.

Getty Images | Buddhika Weerasinghe

The Liver Could Regenerate Itself After Being Removed

While the body often does a magnificent job of patching itself up, there aren’t many parts of the body that will actually fully re-form once they’re removed. One exception is the liver, which has a near-miraculous capacity for regeneration.

This is what makes liver transplants so remarkable. When a person donates a portion of his or her liver to someone with a diseased liver, it is used to replace that patient’s liver altogether. After the surgery, the patient’s new liver will grow to a normal size, while the donor’s liver regenerates back to its own full size.


When You Blush, Your Stomach Lining Also Reddens

When you’re embarrassed, you might feel it on a gut level — literally. The same thing that happens when your cheeks flush from anxiety or embarrassment — a surge of adrenaline causing the capillaries to widen and increase blood flow — happens all over the body, including in your stomach lining. This increased blood flow makes your stomach lining redden as well.


Cracking Knuckles Is The Sound Of Nitrogen Bubbles Bursting

Knuckle-cracking is a divisive activity — you either relish doing it or you loathe everything about it, especially that sound. Either way, the science behind that knuckle-popping sound is fascinating.

The joints in your fingers are lubricated by capsules filled with a liquid called synovial fluid. This fluid is made up of dissolved gases, mostly nitrogen. When you “crack” your knuckles by stretching or bending the fingers, it causes a small nitrogen bubble to form and then burst inside the capsules. That bursting is the cringe-inducing noise you hear when pushing on the finger joints.


Your Heartbeat Changes To Match The Beat Of The Music You Hear

Plenty of love songs speak to the heart metaphorically, but it turns out that music can have a real physiological effect on the heart muscle itself. Studies have found that a person’s heart rate changes when they listen to music, as the heart beats faster or slower to match the tempo. Thus, if you’re looking to relax, lower your blood pressure and slow your heart rate, listening to music with a slow, calming tempo might just do the trick.


Humans Can’t Breathe And Swallow At The Same Time

Unlike many other animals, humans are not able to swallow and breathe at the same time, due to the low placement of our voice boxes. Our airways are the same avenues that allow food to travel down into the body, so any attempt to swallow and breathe simultaneously will usually result in choking.


By Age 60, Most People Lose About Half Their Taste Buds

Although many functions of the human body are downright miraculous, some aspects simply cannot withstand the test of time. It’s a fact of life that our senses are dulled over the years so that by the time we reach old age, our abilities to smell, hear, see and, yes, taste are diminished.

At birth, the average person has about 9,000 taste buds, which are actually mighty resilient and can even regenerate within a few days after being injured (for example, after being burned by a hot liquid). However, older taste buds are less capable of regenerating, and we end up with fewer and fewer taste buds as time marches on, with most people retaining about half their original number of taste buds by age 60.


Skin Is The Body’s Largest Organ

Many of the body’s organs do wondrous things, but one of the most impressive has to be our skin. That’s right. Skin is actually an organ — the largest and fastest-growing organ our body has — and it works hard to protect all of our inside bits. It can grow, stretch, heal itself, regulate our temperature … it’s truly a powerhouse performer.


Everyone Has A Unique Tongue Print

Just like with fingerprints, every human’s tongue has a shape and texture that is unique and different from any other human’s tongue.

In fact, some theorize that the tongue will be used as identification in the future (rather than fingerprints or eyes) because it’s kept hidden inside the mouth and cannot be duplicated without the owner’s knowledge or consent. In this way, it’s perhaps the most pure form of ID we have.

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The Palms And The Soles Of The Feet Contain The Most Sweat Glands

You’re certainly familiar with the sensation of having slick, sweaty palms when you’re nervous, but did you realize that the soles of your feet can also sweat profusely? The palms of the hands and the soles of the feet have more sweat glands than any other part of the body.

However, in contrast to the sweat glands in other parts of the body, such as the armpits, those in the palms and soles produce “emotional sweating” (for example, sweating brought on by stress or anxiety) rather than the kind of sweating that regulates the body’s temperature.


Tooth Enamel Is The Hardest Substance In The Human Body

Though they may be small, teeth are actually quite mighty. In fact, the enamel on our teeth is the hardest substance in the human body, largely made up of a mineral form of calcium phosphate, making it incredibly strong and durable. It’s even harder than steel, though it is more brittle. As we know from studying the remains of early humans, the durability of tooth enamel means that teeth can actually last for hundreds of years.


About 25% Of All The Bones In An Adult’s Body Can Be Found In The Feet

One human foot contains 26 bones, which means that every pair of feet has a combined 52 bones within them. If an average adult human body has 206 bones, this means that nearly 25 percent of the body’s bones can be found in the feet alone. It makes sense that the feet might need more parts, considering all the many things we demand of them on a constant basis, movement, speed, balance and mad dancing skills among them.


You Are Taller In The Morning Than You Are At Night

If you’ve ever trudged to bed feeling worn down from a long day, it may partially be because, well, you have been literally worn down. When we wake up in the morning, we’re taller than we were the night before. Pressure placed on the joints during the day from simply walking around and enduring the effects of gravity causes a small compression in the spinal cartilage and your height actually decreases slightly by nighttime.

Relaxing in bed at night eases the pressure of gravity on the body and replenishes lost fluid in the spine, and we wake up about 1.5 to 2 centimeters taller than we were when we went to bed.


Every Person Has A Unique Smell—Even Identical Twins

Celebrities who release their own perfumes might like to think they’re special for having a signature scent, but the fact is that every human is born with a smell that is unique to them, just like their fingerprint (or tongue!). Each person’s specific scent is called an “odortype” and is determined by a person’s genes. Even identical twins, with all their identical DNA, emit their own individual odortypes.

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The Human Brain Produces Enough Electricity To Charge An iPhone

… if we could only harness it. With its approximately hundred billion electrically conductive wires, the brain naturally produces an impressive amount of electricity. In a piece for Gizmodo, writer Maddie Stone examined just how much electricity could actually be harnessed by the human brain, and ultimately concluded, “If you could somehow divert every single biological wire in your skull to your iPhone’s battery, you’d be fully charged in just under seventy hours!” However, using all of the brain’s electricity would leave little left over for truly necessary functions, such as breathing.


Without The Pinkie Finger, The Hand Would Lose 50% Of Its Strength

Unless you’re Dr. Evil or a frequent tea party host, your pinkie fingers probably don’t get much use on a daily basis, and you might be tempted to see the pinkie as the hand’s most expendable appendage. In fact, however, the pinkie finger is hugely important for supplying power to your hand.

While the index finger, middle finger and thumb work together on the nimble actions of grasping and pinching, the pinkie and ring fingers provide the brawn. If your pinkie were removed, the hand would lose 50 percent of its strength. Hard to underestimate the little guy now, huh?


The Force Of A Human Sneeze Can Be 100 Miles Per Hour

Although the force of each individual sneeze will vary, many sneezes come shuttling out of us at impressive speeds — up to 100 or even 200 miles per hour. This is the body’s way of aggressively ridding itself of germs and irritants, but then those germs are catapulted onto other unsuspecting victims, so it’s always best to cover your mouth when sneezing that powerful sneeze.

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Human Stomach Acid Is Strong Enough To Melt Metal

We all long for abs of steel, but would it comfort you to know that at least the acids in your stomach are powerful enough to melt steel? The acids in our stomach help us digest food and defend our stomachs against viral and bacterial infections. Stomach acid, or gastric acid, is comprised of sodium chloride, potassium chloride and hydrochloric acid — and combined, they have a very low pH level, which means that the fluids are extremely acidic. Stomach acid has such a low pH level, in fact, it’s nearly in the same category as battery acid, which can dissolve steel.


The Brain Isn’t Done Developing Until Age 25

Age 18 is when we’re deemed mature enough to vote and join the military — and when we’re legally deemed adults. It also used to be considered the age at which the brain stopped growing. However, research in recent years has found that parts of the brain responsible for decision-making are not actually done developing until the age of 25, meaning that “adolescence” actually extends into the mid-20s, rather than ceasing at age 18.

For child psychologists, this means that the age range of their clients is now 0-25 rather than 0-18.