The human body is a sophisticated machine, and not even scientists know everything about it yet — or will anytime soon. The things you may know about it are likely the result of decent school education, but they may only be the basics you had to learn to pass a test.
The following list includes facts about the human body that are unknown to most people and could give further insight into why you are the way you are. At the very least, they could help you learn to appreciate your body more!
46 Facts About the Human Body You May Not Have Heard of Before
#1. Science Cannot Really Explain Yawning.
One of the most interesting facts about the human body is that people don’t know why they yawn. Scientists are at a loss in this department and only have theories that may serve as potential reasons, like the fact you don’t breathe as deeply as usual when you’re tired or bored.
In that case, you’re not taking in enough oxygen, so yawning is necessary to introduce more of it into the blood and get carbon dioxide out.
However, that theory isn’t the most reliable one. The theory that most scientists agree on is that yawning helps regulate brain temperature.
#2. Chins Are Unique to Humans.
So many people hate their chins, and yet, they probably don’t know how unique they are. Out of all the animals out there, humans are the only ones who have chins. Not even chimpanzees and apes can be proud of them as their jaws slant inwards.
#3. You Only Need One Kidney to Live.
Most humans are born with two kidneys, and one possible theory behind this is bilateral symmetry. However, you only need one to live — though two may be a better option for staying in great health.
#4. Goosebumps Would Have Made Your Ancestors Bigger and Scarier.
Some obscure facts about the human body are linked to goosebumps, or rather, their evolution. One theory is that they came to be in order to make your ancestors seem more dangerous to predators.
#5. You Have a Preferred Nostril.
Did you know that some humans have a dominant nostril? The bulk of the air usually goes in and out of just one nostril. But the workload is divided between the two — they switch every few hours.
#6. And Your Nose Is Super-Sensitive to All Sorts of Smells.
And speaking of noses, your snoot is so sophisticated that it can detect about 1 trillion different smells!
#7. Your Hair Grows Faster Than You Think.
As slow as it may seem, your hair grows pretty fast. Every year, it may grow around six inches. The only thing that grows faster in your body is bone marrow.
#8. Cracking Knuckles Bursts Gas Bubbles.
One of the strangest facts about the human body revolves around your knuckles. Some people believe that cracking them means you’re somehow putting them in place. But really, those satisfying cracks are bursting gas bubbles. It’s sort of like popping bubble wrap, but in your hands or feet instead!
#9. Fingertips May Serve Various Purposes.
Strangely enough, scientists don’t know why people have fingertips. One theory is that they help improve touch perception. However, they may also help you grip better onto surfaces, especially in wet conditions.
#10. The Thumb Has Its Own Pulse.
You cannot take someone’s pulse with your thumb, as it has its own pulse that makes it difficult to get accurate results. Instead, you should use your middle and index finger.
#11. Your Heart Doesn’t Experience Fatigue.
The cardiac muscle is the only muscle that never gets tired. It doesn’t need any rest, so its action is continuous and automatic.
#12. Special Hair Grows Around Your Belly Button to Catch Lint.
Some of the weirdest facts about the human body are linked to that hole in your stomach — the belly button. One of them is that there are special hairs growing in a circular pattern around the belly button that capture all sorts of fibers. These hairs have tiny scales that help them latch onto the fibers and collect them.
#13. If You Poke Your Belly Button, You May Feel an Urge to Pee.
And speaking of belly buttons, have you ever poked yours and immediately experienced some discomfort in your bladder? That’s because by poking it, you can stimulate your stomach’s very sensitive internal lining.
#14. You Really Don’t Need Your Wisdom Teeth.
You’ve probably taken out your wisdom teeth by now, and rightly so, as they are pretty useless. Wisdom teeth were once a powerful asset to your ancestors and served as the third set of molars, providing more chewing power and reducing excessive wear.
Today, you don’t need them, as the human diet has changed. Besides, they can be a nuisance as they can crowd the teeth (your jaw is, after all, not as big as your ancestors’ were).
#15. Fingernails Are Flattened Claws.
Your fingernails are supposed to help you grip onto things and pick stuff off and up. However, they weren’t always flat — they evolved to be like that as human ancestors started using tools. Suddenly, there wasn’t a need to have claws anymore, so those curved keratin growths disappeared or rather turned into broader, flatter claws.
#16. Your Tongue Is Mainly Muscle Tissue.
These facts about the human body keep getting weirder. For example, did you know that the human tongue has a lot in common with an octopus’ tentacle or an elephant’s trunk?
All three are muscular hydrostats, a unique biological structure consisting mostly of muscles. They don’t have any skeletal support, so the muscles do all the work — in an elephant’s case, this makes its trunk super-flexible and able to move in any direction.
#17. And It Could Serve as a Form of Identification.
Similar to fingerprints, humans have unique tongue prints that can serve as biometric authentication tools.
#18. Women Have More Taste Buds Than Men.
The tongue also has about eight thousand taste buds on it. Even more curious, women usually have more of them in comparison to men, making them much better tasters overall.
#19. The Number of Bones Decreases With Age.
When you’re born, you have about 300 bones in you. Once you become an adult, though, you’re left with 206 bones, as the others have fused together as you grew.
#20. Your Brain Could Be Bigger Than You Thought.
Some of the strangest facts about the human body involve the brain, and one of them is that it could be much bigger if you were to flatten it out. If you removed all of the wrinkles, it would be the size of a pillowcase.
#21. The Heart Pumps About 2.5 Million Liters of Blood a Year.
The human heart pumps a lot of blood. In fact, it could pump enough to fill an Olympic-size pool in just one year!
#22. The Cornea Doesn’t Have a Blood Supply.
But there’s one part of the body that doesn’t need any blood vessels. The cornea obtains its oxygen directly from the air when you are awake.
#23. You Cannot Breathe and Swallow Simultaneously.
It’s important that you pay attention to your breathing while eating, as you cannot swallow and breathe at the same time. Once again, the reason for this is evolution.
Humans have evolved to have lowered voice boxes, which resulted in a connection of food and air passageways and the creation of epiglottis. This leaf-like flap of cartilage seals off the windpipe when you’re eating to prevent you from inhaling food.
#24. You Are a Vessel Full of Bacteria.
Bacteria is all around you and even in you. On average, you’re carrying around about two to six pounds of bacteria in your body.
#25. Babies See the World Differently When They’re Born.
Little-known facts about the human body also include the one about newborn babies seeing the world upside down. This lasts only a little while — until the brain learns to flip the raw data formed on the retina. The retina captures images upside down, so the eyes and the brain have to learn how to sort them out and process them properly.
#26. Damage to the Left Side of the Brain Would Affect the Right Side of the Body — and Vice Versa.
Another strange brain fact is that the left and the right side of the brain don’t control their own sides. Instead, they are inverted, with the left controlling the right side of the body and the right controlling the left.
#27. Newborns Will Cry But Shed No Tears.
No matter how much they cry, newborn babies don’t produce tears. This ability usually becomes available toward the end of the first month when their lacrimal glands fully develop.
#28. There Are Different Types of Tears You Can Cry.
The basal ones are there to nourish, lubricate and protect the cornea, while reflex tears aim to wash away irritants. Emotional tears are, of course, a response to certain life situations, and according to some scientists, they may contain additional proteins and hormones that aren’t found in the other two types.
#29. Scientists Have Found 30+ Blood Group Systems.
There aren’t only a few blood types you can be — science has uncovered more than 30 other blood group systems. However, the ABO system simplifies it a lot, putting humans into four main categories: O, A, B, and AB.
#30. Your Shed More Dead Skin Than You Think.
Have you ever wondered why your home gets so dusty every week? Well, every hour, humans shed lots of dead skin — about 600,000 particles, which equals about 1.5 pounds per year!
#31. Stomach Acid’s pH Levels Are Similar to Battery Acid.
It’s good that humans have a strong stomach lining. It has to be strong enough for stomach acid, which could dissolve metal.
#32. Both Smell and Taste Help Distinguish Flavor.
When determining the flavor of something, you usually focus on how it tastes. But flavor doesn’t depend on taste alone — it’s a combination of smell and taste perception.
#33. Your Left Lung Is Vastly Different From the Right One.
Your lungs aren’t exactly carbon copies; in fact, they don’t even have the same number of lobes. The right side has three lobes, while the left has only two. The left side of your lungs is also a bit smaller as it has to free up some space for your heart too.
#34. Your Strength Falters If You Lose Your Pinky.
Half of your hand strength depends on your pinky finger. Losing it would be detrimental and reduce your grip strength.
#35. Ear Wax Serves as Protection.
The yellow gunk found in your ears is a necessity. Ears are self-cleaning, and ear wax helps keep them clean as well as protected from all sorts of bacteria.
#36. Your Brain Is a Powerful Natural Computer.
It has been said that it has a data capacity equivalent of about 10 to 100 terabytes. And that same brain holds so much information, right until the end of your life. By the end, you should be able to recall about 150 trillion pieces of it!
#37. Only the Lucky Few Can Remember Their Dreams Vividly.
But alas, that doesn’t include your dreams. On average, a person usually forgets about 90% of them. In fact, humans often forget about half of the details five minutes after the dream ends.
#38. Fingertips Form Early on in the Womb and Remain the Same Forever.
Fingertips are created in the womb in the 24 weeks after conception and are unique for everyone, even twins.
#39. You Cannot See It, But Blushing Also Affects Your Insides.
When you’re blushing, your stomach turns red too.
#40. Left-Handedness Is Rarer Than You Think.
Only about 10% of the population is left-handed, and just about 1% is ambidextrous.
#41. All of Your Hair Isn’t Growing at the Same Time.
About 90% is actively growing while 10% is resting at any given time.
#42. Brains Shrink During Pregnancy.
A study revealed that gray matter is reduced in pregnant women to facilitate better processing of social signals, and in particular, recognizing the baby’s emotions and needs.
The reductions remain for at least two years after the pregnancy, so essentially, women’s brains can experience long-lasting changes if they ever decide to become mothers.
#43. Closing Your Eyes When You Sneeze Is an Autonomic Reflex.
You could try to sneeze with your eyes open. Just know that it would require some conscious effort to override the reflex.
#44. You’re About 1 cm Taller in the Morning Than at Night.
While lying down, the spine decompresses and spreads out. As the day passes, the soft cartilage in your spine and knees compresses, so you shrink again.
#45. You’re Probably More Like Your Dad (at Least Genetically Speaking).
Humans are usually more genetically similar to their fathers due to an imbalance in gene expression that favors dads. You get one copy of each gene from both your parents, but they may not be equally active while you’re being created.
#46. You’re Literally Glowing But Cannot See It.
And finally, here’s one of the most interesting (and rather obscure) facts about the human body — humans produce a glimmer of light that rises and falls during the day. That light is a byproduct of biochemical reactions in the body.
However, it is too dim for your eyes to see, with the intensity being a thousand times lower than what the naked eye could recognize.