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Speaker 1: Welcome to brain stuff from how stuff works. Hey, brain stuff,

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Speaker 1: it's Christian saga, and I'm here to tell you why

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Speaker 1: human beings have eyebrows, because look at them. Take take

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Speaker 1: a clus look, go over to the mirror. Look, aren't

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Speaker 1: they just ridiculous? I mean, they're also very well manicured,

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Speaker 1: but they're also ridiculous. Now, scientists aren't entirely sure why

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Speaker 1: we have this hair, but they have a pretty good guess.

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Speaker 1: The arch shape of the eyebrow diverts rain or sweat

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Speaker 1: around to the sides of our face, keeping our eyes

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Speaker 1: relatively dry. And the most obvious advantage of this is

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Speaker 1: that it allows us to see clearly even when we're

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Speaker 1: sweating a lot, like on a first date, or when

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Speaker 1: we're out in the rain or something like we're standing

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Speaker 1: out of somebody's house screaming at them to come out

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Speaker 1: for our first date with us, but then they call

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Speaker 1: the cops. All right, never mind. Diverting the sweat away

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Speaker 1: is also good because the salt in sweat irritates our eyes.

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Speaker 1: But just to test things, I shook a salt shaker

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Speaker 1: into my eye and take it from me. It burns

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Speaker 1: like hell fire. Eyebrows are a very significant aspect of

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Speaker 1: our appearance. They are one of the most distinctive features

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Speaker 1: that make up our faces, and we pay a lot

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Speaker 1: of attention to them and look. Eyebrows are also one

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Speaker 1: of the most expressive facial features. One of the clearest

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Speaker 1: ways we're telling somebody what we're thinking is to simply

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Speaker 1: move our eyebrows up and down. But what if we

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Speaker 1: didn't have eyebrows. Scientists have thought about this as well,

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Speaker 1: and they think that if we didn't have eyebrows, we

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Speaker 1: would have gotten instead these long snuffle luck bagus style eyelashes,

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Speaker 1: as well as far protruding foreheads, which could have been

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Speaker 1: kind of useful because we could put things up there,

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Speaker 1: I don't know, like like our keys, but rain or

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Speaker 1: sweat would then drop from that ledge on our face

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Speaker 1: straight away down onto the rest of our face without

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Speaker 1: getting into our eyes. So all right, way to go

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Speaker 1: evolution for not making us look like that. Check out

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Speaker 1: the brainstuff channel on YouTube, and for more on this

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Speaker 1: and thousands of other topics, visit how stuff works dot com.