‘What’s a fact about the human body that not many people know about?’ – 30 jaw-droppers

Today’s biology lesson comes courtesy of Redditor Zenssei who had a question about the human body for the good people of askReddit.

What is a fact about the human body that not many people know about?

And we’re glad they did because it prompted lots of fascinating and surprising replies, only some of which probably need a fact check.

Here are our favourite 30.

1.

‘Humans have, on average, just as many hairs on their body as chimpanzees, human hair is just a lot shorter and finer.’
Inner_Inspection6408

2.

‘If you squirt warm water into someone’s ear with a syringe, their eyes will automatically turn to the side that you squirted the water. If you use cold water, their eyes will automatically turn to the other side.’
Cruithne

3.

‘Every minute you shed over 30,000 dead skin cells off your body.’
ae1021

4.

‘You can grow a new human being faster than most missing toenails can grow back.’
CurrentAttention3

5.

‘If you faint at the sight of your own blood you may have an oversensitive vasovagal response. The theory is that this developed as a survival mechanism, kind of like an opposum playing dead.’
shibapop

6.

‘You hate the sound of your recorded voice because it’s missing the low frequency you’re used to hearing. When you talk, you hear your voice as it goes to the air and back to you ear. It also goes through your skull to your ear, and this bone conduction mechanism transmits the low frequencies better than air does. Your recorded voice only has the air transmitted sound. That causes the dissonance between what you think your voice sounds like, and what it really does. It’s also why your voice will (almost) always be higher pitch than you think.’
BlocterDocterFocter

7.

‘Our brains make up, on average, around 2% of our body weight but consume 20% of our caloric intake.’
MoodyTeeth

8.

‘Pregnant women have 50 percent extra blood!’
centaurquestions

9.

‘The surface area of the lungs is about the same size as a tennis court.’
felipebsr

10.

‘Humans are one of a few species of mammal that oddly don’t produce their own vitamin C due to lack of a certain enzyme. Other mammalian species who exhibit this mutation are those contained in the main primate suborder Haplorhinni (monkeys, apes, tarsiers), as well as bats, capybaras, and guinea pigs. All other mammals produce vitamin C in the liver.’
TexasPatrick

11.

‘The eyeball is the fastest healing part on your body.’
_Nugget_UwU

12.

‘Your brain regulates how strong your muscles are. If your leg muscles were to contract at full strength, they would snap your femur. It’s why people in emergencies on adrenaline can lift cars off children. Your body is capable of great strength, but it could also severely damage you, so your brain keeps you a weak, soft bag of jelly.’
Andibular

13.

‘Apparently about 20% of people have a bony ridge on the roof of their mouth. Most people’s pallettes are smooth with a very slight ridge.
The 20% like me have an exaggerated and more pronounced ridge. Apparently it’s most common in women and Asian folk, and I’m neither so that’s neat. I always thought it was totally normal.’
Alagane

14.

‘Your brain likes stimulation, if it doesn’t get any it will make some up, some people are more sucepticle to it then others, the colors you see before you fall asleep are a common mild occurrence, there are several classes of these hallucinations, closed-eye visuals, which are caused by leaving your eyes closed for a long time, hypnagogia, which is caused by the onset of sleep, prisoners cinema, which is caused by looking into a dark place for a long time, ganzfeld effect, which is caused by blocking out all external stimuli, and Charles bonnet syndrome, caused by sight loss. Most are these are simple phosphenes but some can be whole imagined scenes, or more abstract fractal-like imagery’
NoCommunication7

15.

‘The average adult has 22 square feet of skin. Perfect size for a nice rug.’
angry_centipede