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- [Narrator] There's a creature scurrying
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across your face right now. Yes, you,
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and at some point, maybe now, maybe in a few days,
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it's going to find a nice cozy pore in your skin
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and lay a single enormous egg.
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Meet the face mites. They're smaller than a grain
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of sand, are a kind of arachnid like spiders,
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and they feast on the oil and cells in your skin,
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particularly on your oily nose, cheeks, and forehead.
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Scientists suspect they've been living on us
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since the dawn of humanity over 200,000 years ago,
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and today, studies suggest practically every adult
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on the planet has thousands of them.
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Odds are you've been living with them your whole life.
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Babies quickly get them from their parents
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a few days after birth, and once those face mites
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are on you, the only thing they enjoy as much
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as slurping oil and nutrients from your pores is
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having sex all over your face.
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Afterwards, females burrow deep
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into your pores where they lay their eggs.
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The eggs end up in one of two places
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depending on the species of face mite.
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The first species, called Demodex folliculorum,
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lays its eggs in your hair follicle,
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while the second prefers nesting in your sebaceous glands.
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And in under two weeks, the babies hatch,
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mate, lay their own eggs and die,
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leaving behind a pile of decomposing corpses.
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Now, you can wash some of this off,
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but you'll never eradicate them completely
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because even if you treat them with antibiotics,
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they'll return in about six weeks, tops.
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You'll pick them up from towels, pillows,
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and your loved ones.
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Well, that all sounds horrific,
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but usually face mites are harmless.
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They only become a problem when they multiply
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out of control. This can happen in people
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with an impaired immune system.
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It's also been seen in people with a painful skin
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condition called rosacea.
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Normally, you'll have around one or two mites
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per square centimeter of skin,
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but one study found that people with rosacea
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had 10 times the normal amount.
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Believe it or not, in some cases,
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face mites can be useful.
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Researchers can actually study your face mites
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to learn about your ancestors.
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You see, most mites often stay within a community.
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So over time, they've evolved into distinct lineages
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in different geographic regions, and by comparing
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their DNA, scientists can trace how different groups
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of humans migrated across the world.
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For example, a study found that European mites
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genetically diverged from East Asian mites
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around 40,000 years ago.
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That's the same time European and East Asian humans
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parted ways. Pretty handy.
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So when it comes down to bugs crawling all over you,
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it could be a lot worse.