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WATCH: How Are Tattoos Permanent, When Humans Shed So Much Skin?

Half your body weight in a lifetime.

BEC CREW
9 DEC 2016
 

 

Here's a disgusting fact for you - every hour, you'll shed around 0.085 grams of dead skin, or roughly 500 million skin cells. That might not sound like much, but add that up over a lifetime, and you're looking at 35 kg (77 pounds) of discarded flesh, which is around half the entire body weight of an average human.

But with all that shedding, how do our tattoos stay put for years, centuries, and even millennia?

 

As the Ted-Ed video above explains, the way we apply tattoos is brilliant, and while we've come a long way since the earliest known tattoos, you really don't need to get that technical to master permanent body art.

If you're wondering what the oldest known tattoo is, well, that's kind of a contentious subject, because while Ötzi the Iceman sure had a lot of tattoos - ones that have survived for 5,000 years - a lesser known contender could outdo him not in number, but in age.

The El Morro mummy from Chile, with his tattooed-on moustache could be even older than that, and all these guys had to do to make their tattoos permanent was rub charcoal into very fine incisions cut into the skin.

It was thanks to none other than Thomas Edison that our tattooing techniques have become far more advanced, with modern electric tattooing guns taking inspiration from Edison's electric pen - a motorised engraving machine that ultimately flopped.

But thanks to his invention, we now have an incredibly precise way to get ink where it needs to be to remain permanent - the dermis layer of the skin. 

 

This layer sits under the epidermis, which itself is made up of layer upon layer of skin to form a protective outer barrier for our bodies. While we replace our entire outer layer of skin every two to four weeks, the dermis below stays put.

So it really doesn't matter how much skin you slough off in the shower - your tattoo will always be there.

But it's not actually that simple, because while all that ink might avoid the shedding process, there's no avoiding the body's immune system, which doesn't really take kindly to you injecting foreign substances into your dermis.

Check out the Ted-Ed video above to find out how your immune system tries - and fails - to remove all that ink from your body, and why this process is actually crucial to ensuring that it sticks around.

And if you want to see something truly fascinating/kinda gross, I'm just gonna leave this here:

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