This SciShow is for all the lonely hearts out there. The ones watching this on a Saturday night while all their friends are out partying. 
 
Don’t worry… you’re not alone.
 
You have hundreds of animals living on your face.
 
It’s not the first time we’ve mentioned this; our bodies are practically five-star hotels for parasites, mites, and other creepy crawlies. 
 
The ones we're talking about here are called demodex mites, and your face is the perfect place for them to set up shop.
 
Demodex mites are microscopic arachnids -- relatives of spiders and ticks -- that live around the hair follicles and oil glands of mammals. 
 
Humans carry two species of these little guys, and they both love our skin so much that they refuse to live anywhere else. 
 
One is Demodex folliculorum, which is bigger and has a rounder bottom; and Demodex brevis, which is smaller and has a pointy bottom.
 
But even though studies have shown that almost every human being on earth carries these mites, we were not born with them. That would be weird if they were in the uterus with that...oooeewwhh...
 
They came from our earliest contact with other humans -- most likely, our moms and dads when they, like, nuzzled us when we were babies. And ever since then we’ve been sharing them with everyone else we rub our faces on -- like friends, siblings, prom dates... 
 
The mites like to congregate around our eyebrows and nose and eyelids, cheeks, chin, forehead… pretty much anywhere that’s got a lot of sebum, the oil secreted from the sebaceous gland that helps keep our skin waterproof and moisturized. And these glands are often located around the hair follicles on our faces. 
 
And, if you have to eat something secreted from someone else’s face, sebum is actually pretty nutritious. So once we, as the hosts of demodex, hit puberty and start producing lots of oily sebum, we end up with thriving colonies of them. 
 
So, the mites aren’t exactly beneficial to us, but they aren’t very harmful either … unless they get too comfortable.
 
An overabundance of foraging mites probably contributes to irritating skin conditions like eczema and rosacea. 
 
How? Well, it has to do with the way these mites... poop.
 
See, they don’t actually defecate. Not even one time in their entire lifetimes. 
 
They just hold it all inside of themselves until they die, and when they do, the waste just spreads all over as their bodies decay. 
 
And new research suggests that the bacteria in mite feces might be what cause irritations of the skin.
 
But for the vast majority of people, there’s no reason to go scrub your face for the next few hours or anything. You’re not going to get them anyway.
 
We’ve probably always had these mites, ever since humans became humans, just like the bacteria we carry with us in our guts. 
 
So, take heart. You are not alone in this world! You have tons of tiny spider-like creatures on your face to keep you company.
 
I’m Hank Green. Thank you for watching this episode of SciShow -- to both the humans and the mites because I assume the mites were watching as well. If you want to know more about the inhabitants of your face or feet or gut, go to youtube.com/scishow and subscribe.