What are some of the coolest things the human body does that people don’t know about?

1. The way you lose weight is through your breath. When your body burns fat, it breaks down into water and CO2, which you exhale.
   — nidalmorra


2. The heart has like 5 backup procedures in case it starts to fail.
   — prostateExamination


3. Scientists only recently figured out why we don't just leak all the time. Given that we're regenerating our skin entirely every 4 weeks or so, it's baffled people as to how there's never seepage or holes. Turns out our skin cells are simply shaped for optimum tessellation - tetradecagon, 14 edges I think. If I remember the story right some scientist spent years and years figuring out the best way for things to fit together and came to the conclusion that 14 edges was peak. Turns out our bodies have been doing that for years and years and years and years. Also from the same podcast (No Such Thing as a Fish) someone figured out that if you took all the DNA from all the cells in the average human body. There would only be about 2% human DNA in there - we essentially harvest and host a fucking heap of other things inside our body to the point where we actually make up a negligible amount of ourselves.
   — HueyLewisAndTheShoes






4. When someone gets electrocuted and flies backwards it isn't from the electrical current. It is actually caused by the quick contraction of their muscles. In other words if we could figure out how to harness that contraction, humans would be capable of jumping upwards of 20 feet from a resting state.
   — Bearded_Anchor


5. The thymus (an immune organ) starts to shrink once you hit puberty and is eventually just replaced by fat. Wow your body actually programmes itself to intentionally lose an organ??? Cool
   — raindropcapsule


6. The Liver can regenerate itself, even if ~75% of it has been removed. Also, your body can survive without a stomach, a lung, a kidney, the spleen, the gall bladder, and even one brain hemisphere, though removal of these organs (except the kidney) can be dangerous and you may need to take supplements for the rest of your life.
   — GeneralDarian






7. All the cells in your body are replacing themselves at different rates. Skins cells every few weeks, bones every few years. This means you are not the same person you were seven years ago. It's kind of a Ship of Theseus thing. (Or Trigger's Broom, if you prefer.)
   — jdgood


8. When you pronate your forearm, (turning it palm side up to palm side down), the 2 parallel and straight bones (ulnar and radius) actually cross over each other to form something similar to an X shape!!
   — raindropcapsule


9. The gut contains 1/3 of our bodies neurotransmitters. Kicker is that inside of the gut lives a foreign mass of bacteria that interacts with these transmitters. The next time you eat ask yourself, am I eating what I choose to eat or am I eating what the bacteria crave?
   — PMmeyourbirdfeeder






10. Your brain rewires itself a lot. If you lose a limb, then the control part for that limb will eventually be taken over by other functions, which still confuses the brain sometimes and cause the "ghost limb" sensation.
    — Stockholm-Syndrom


11. There is a hormone driven clock that flip-flops every 10-15 minutes give or take, that makes one nostril/sinus slightly more constricted than the other. However, you only ever notice it when you have sinus congestion. Have you ever had a cold where one nostril is closed completely solid with mucus, and no amount of Kleenex blowing will clear it, but then minutes later, it's suddenly the other nostril that's blocked shut? This is an intentional auto-immune defense of your body.
    — verdatum


12. [This video](https://www.youtube.com/watch?v=FzcTgrxMzZk) is a rendering of the activities that are going on in your cells every minute of every hour of every day. It's such an intricate dance. It's amazing that we can even function. I can understand now how a single error in someone's genetic code could cause everything to break down.
    — CrimsonSmear






13. Goosebumps are actually little muscles that attach to your hair follicle that make it stand up. This process is in response to fear or coldness. In animals, their hair stands up to thwart away predators. In humans, it doesn't do that - but it's the same muscle that pulls your follicle up.
    — Back2Bach