22 Wild Facts About The Human Body That Are Actually Really, Really Fascinating

The human body is a mysterious thing. And recently, when redditor u/Hot_Banana_Ice-cream asked the internet, "What is a creepy fact about the human body?" I learned wayyyyy more about the human body than I anticipated. Some are a bit TMI, but I'm still mind-blown.

Here are some of the most shocking — and fascinating — responses:

1."If you try on those specialty glasses that vertically invert your vision so everything is upside down, your brain will eventually adjust to it, and things will look 'normal.' But when you take those glasses off, everything will still appear upside down until your brain recalibrates again."

—u/shadow29warrior

2."Bodies will move as they’re coming out of rigor. I’ve been bumped by a few (I’m a coroner). Bodies can also make sounds as the remaining air/gas leaves...2 a.m. in the morgue, and I thought I was in Call of Duty: World At War — Zombies."

—u/Jar-JarShotFirst69

3."Your rectum is lined by cells similar to those inside your mouth."

—u/GasTsnk87

4."Our brain filters out a lot of what we see, along with just straight making things up based on extrapolation."

—u/AdmiralClover

5."We don't just have one anal sphincter. When poo comes along, it passes another inner sphincter which isn't under voluntary control. Meaning you can do oOoOoO with your outer sphincter, but not the inner one. (You tried, that's okay.) Sensory cells can detect whether you're about to pass gas or solid. From toddler age on, you can decide to go or not to go. If the time isn't right (e.g. at a friend's house or no toilet nearby), the inner sphincter can push the poo back and store it there for later. That's why sometimes if you need to do a number two but don't go, the urge goes away after about 20 minutes later. (But seriously, go if you can. Constipation risk.)"

—u/bmb00zld

6."The front of your tongue is curious, constantly patrolling, and autonomous. It chases the dentist around your mouth and you aren’t even aware of it. So embarrassing and weird/creepy."

—u/AdeleBerncastel

"In dental school, I learned this fact when practicing taking impressions on each other. My buddy’s tongue kept licking my finger. I asked him to quit licking me, and he was like, 'I can’t help it!' And then, we switched places, and my tongue wouldn’t leave him alone. And for those of you that don’t think your tongue does this: Some of you are right. But the majority of you just think your tongue is behaving, but it is all over the place without you even knowing."

—u/recoveringcultmember

7."When you get laser tattoo removal, the ink doesn’t disappear — you pee it out (it can also be discarded through your poop or sweat). Your body’s immune system breaks down the pigments of ink, and it flows in your blood stream, gets processed through your kidneys, then you pee out the ink."

—u/Fine_wonderland

8."My favorite fact is that both your eyes have a blind spot, where the optic nerve is. A lot of people don't even know it exists, and even if they do, it is bigger than people often think. And it's also really easy to demonstrate to people if you know how. It's one of my favorite bar tricks: All you need is a pen and a napkin to draw a cross and a dot. Here's an alternate demo."

"If it doesn't work, you're doing something wrong: not getting close enough, the image is too small on your phone, you're not closing the correct eye, or not keeping your gaze fixed on the cross. It isn't because you don't have a blind spot."

—u/M0dusPwnens

9."Sometimes, there are just random extra muscles. You can go your entire life without even knowing it. I've worked as a mortician, and the medical examiners would tell me about some cases like this. Also, there can be random tumors, even when the individual had never been diagnosed. Lastly, skin sounds like plastic wrap when peeled from the body."

—u/Mean_Negotiation5436

10."You can become allergic to yourself."

—u/RCKJD

11."A pregnant corpse will build up enough gas to expel the fetus even after death. Look up 'coffin birth.'"

—u/TeamWaffleStomp

12."We ate our own hair (called lanugo) while inside the womb. According to Ovia Health: Fetuses 'eat the lanugo that they shed while in the womb, and it builds up within them to form the substance that makes up their first poop, known as meconium.'"

—u/thisismehhh

13."The brain will always/usually try to ensure its survival; if knocking you out does so, then you will faint for the safety of the brain."

—u/SonicBoom500

14."In really bad cases of endometriosis, endometrial-like tissue can grow throughout the body, like the bladder, intestines, near the chest — and even in the brain in rare cases. It’s incredibly painful, since it still tries to ‘shed’ like a normal period but has nowhere to go. Endometriosis can only be confirmed via surgery, since it doesn’t show up on most ultrasounds/MRI scans."

—u/Wise_Neighborhood499

15."Biologist here. When it comes to sunburn, the scary thing about UV damage is that it's not minor radiation damage. It is literally strong enough to cause double stranded DNA breaks. Broken genes that can lead to cancer are largely because the body fails to repair DNA damage (which is directly correlated to copy errors that end up occurring in mitosis as a result). Well, double breaks like this are the hardest to repair. UV damage is no joke. It will also age your skin earlier, too."

—u/GeneticsGuy

16."The intestines are covered by a double 'fleece' of peritoneum. Think of it like a blanket. When your intestines get damaged for whatever reason, this blanket starts moving out of itself and crawling upwards toward the place that has the injury. It will stay there until the injury is recovered, and then it will move on again."

—u/Appropriate_Donkey18

17."Human beings are a cesspool of bacteria, and when you die, your body eats itself from the inside out."

—u/FukU6050

"There's more bacteria than human cells in our bodies."

—u/Junkman3

18."You can grow tumors with hair, teeth, and eyes."

—u/tgoundrey

"I've had two of those! The one I had removed when I was 18 was full of different bits of bone, hair, teeth, and when it grew back when I was 29, it was half hair, half sebum."

—u/deenz

19."There is a myth that your fingernails continue to grow after death, which is supposed to explain why dead bodies often appear to have long nails. The truth is that the soft tissues in the fingers and hands tend to contract as they lose moisture, leading to the appearance of growing nails."

—u/Draculamb

20."Food that was consumed can sometimes take up to five days to fully pass through your intestines into your colon. So, when people say that you are full of sh*t, they ain't lying."

—u/sk8r772001

21."One thing that spun me out was hearing about fallopian tubes after a friend went through emergency surgery. Fallopian tubes are mobile and active parts of your reproductive tract. When one tube isn't there or is 'broken,' the other tube can actually move over to the opposite ovary and 'pick up' an available egg."

—u/quacker1982

And finally...

22."Human skin is overlaid with a pattern called Blaschko lines, which are stripes covering the body from head to toe. The stripes run up and down your arms and legs and hug your torso. They wrap around the back of your head like a hood and across your face. You just can’t see them."

—u/DadsRGR8

WOW. Which fact surprised you the most? What are some other "creepy" things about the human body most people don't know? Let us know in the comments below!

Note: Some responses have been edited for length and/or clarity.