Recently, Reddit users were asked to share the most interesting facts about the human body that most people don’t know, and they didn’t disappoint. Here are some facts about the human body that may shock, dumbfound, or just plain weird you:
1. “Babies don’t have true kneecaps until they are about two years old. Their kneecaps are tiny, soft cartilaginous beans that begin to grow and harden in the first two years. They only become fully developed around school age.”
Litra Images/Getty Images
——Clarbadse
2. “Your stomach grows a new lining every few days, otherwise it would just digest it on its own. The body is just so low-key and wild.”
——Glimcherist
3. “You’re taller in the morning than at night. During the day, your spine is slightly compressed by your weight. The difference can be as much as 1-2 centimeters.”
—amaya_mamay
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4. “The tongue is the only muscle in the body that is not connected at both ends.”
——Comfortable glass shards
——Cinnamon rolls
6. “When you cry, you get a runny nose because there’s a little tube that connects the two, called the nasolacrimal duct.”
—kyledotcom
7. “Because it takes time for neurons to transmit signals to the brain, you’re essentially always living in the past and never truly experience the ‘now.'”
—enough-Bag3242
8. “Skin wrinkles in water because the brain triggers the autonomic nervous system to constrict blood vessels under the skin, reducing tissue volume, while the outer layer of skin remains the same size. This involuntary, neurally controlled response—not just water absorption—creates ‘prune’ skin to improve grip on wet objects.”
—richj43
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9. “Your brain doesn’t actually feel pain. That’s why brain surgery can be done while the person is awake. The pain you feel from a headache comes from the tissue surrounding the brain, not the brain itself.”
—CloudNineGurl
“Yes! I’m an anesthesiologist and occasionally do awake craniotomies. We basically anesthetize the scalp with lots of tiny injections of anesthetic medication, and then I gently sedate the patient (they’re kind of asleep, but without a breathing tube or general anesthesia) until the skull is fully open. We then wake the patient up for critical parts of the case and have someone keep talking/talking to them until the surgeon is done.”
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—Credit_and_Forget_It
10. “One nostril almost always breathes better than the other, and it switches every 2-6 hours. This is called nasal circulation.”
——Phylance Bioli
11. “Splashing cold water on your face triggers the mammalian dive reflex, slowing your heart rate and increasing the time you can hold your breath.”
—Alex MC69
12. “You all know that knee-jerk reflex, where the doctor hits the patella and then suddenly kicks? We have the same reflex for the ball, called the cremasteric reflex. Anyway, don’t ask why and how I know that.”
—LasgdReturn
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13. “The hyoid bone is the only ‘floating’ bone in the body and is located in the throat.”
—Ouroboros 567
14. “Some women can produce milk from their armpits or even their thighs. Just like other mammals, the body can produce extra milk.”
— Vegetable Reindeer 724
15. “Humans glow slightly in the dark. Our bodies emit trace amounts of visible light due to chemical reactions, but our eyes are too weak to see it.”
—Gamer–Boy
16. “When you do a kidney transplant, they don’t remove the failed kidney.”
——militia disfruita
17. “Your intestines ‘know’ where they are supposed to be in your body, so the doctor can just put your intestines back into your body and they will return to normal on their own.”
——-_-_Porter_-_-
18. “Our nose is always visible, but our brains just ignore it.”
Yulia Burmistrova/Getty Images
——Just another strong man
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19. “Your body can compensate for clogged blood vessels by growing new blood vessels. ‘Organic’ bypass happens all the time, and most people don’t even know it.”
——Pink Aunt 007
20. “Your eyes have a different immune system that’s completely independent of the rest of your body. If your regular immune system detects that you have eyes, it attacks them as foreign objects.”
—Euphorix126
twenty one. “Your gut flora has amazing control over your body.”
—Install i select i
twenty two. Finally: “There is an exchange of saliva between the baby and the breastfeeding mother. The mother’s body analyzes the breast milk and if the baby starts to get sick, it sends antibodies to help the baby recover. The breast milk also changes throughout the day: more water during the day, more fat at night. If breastfeeding works for you, it’s a beautiful thing. The human body is amazing!”
Sanya SM/Getty Images
—KMang3
What’s a fascinating fact about the human body that sounds false, but is actually true? Tell us what you know in the comments, or you can submit your facts anonymously using the form below.
NOTE: Some facts have been edited for length and/or clarity.
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