WEBVTT - Why do human beings have eyebrows?

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<v Speaker 1>Welcome to brain Stuff from house stuffworks dot com where

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<v Speaker 1>smart happens. Hi Am Marshall Brain with today's question, why

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<v Speaker 1>do human beings have eyebrows? Scientists aren't entirely sure why

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<v Speaker 1>we kept this hair, but they have a pretty good guess.

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<v Speaker 1>We know that eyebrows help keep moisture out of our

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<v Speaker 1>eyes when we sweat or when we walk around in

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<v Speaker 1>the rain. The art shape diverts the rain or sweat

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<v Speaker 1>around to the sides of our face, keeping our eyes

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<v Speaker 1>relatively dry. The most obvious advantage of this is that

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<v Speaker 1>it lets us see clearly when we're sweating a lot

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<v Speaker 1>or when we're out in the rain. Without eyebrows, getting

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<v Speaker 1>around in these conditions is a little more difficult. Diverting

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<v Speaker 1>this sweat away is also good because the salt and

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<v Speaker 1>sweat irritates the eyes, making them sting a little. Eyebrows

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<v Speaker 1>are a very significant aspect of our pearance. They are

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<v Speaker 1>one of the most distinctive features that make up our faces,

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<v Speaker 1>and we pay a lot of attention to them. We

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<v Speaker 1>think of some types of eyebrows as attractive and some

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<v Speaker 1>is unattractive, and many people spend as much time preening

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<v Speaker 1>their eyebrows as they do applying makeup to their eyelashes

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<v Speaker 1>or lips. Eyebrows are also one of our most expressive

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<v Speaker 1>facial features. One of the clearest ways to tell somebody

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<v Speaker 1>what you're thinking is to simply move your eyebrows up

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<v Speaker 1>or down. We all know what different eyebrow positions mean,

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<v Speaker 1>so eyebrows obviously serve a lot of functions for our faces.

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<v Speaker 1>There's beauty, nonverbal communication, distinctive appearance, the whole water shedding thing.

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<v Speaker 1>But most scientists are inclined to believe that if we

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<v Speaker 1>didn't have eyebrows, something else would have evolved to help

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<v Speaker 1>the situation. For example, humans could have developed incredibly thick

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<v Speaker 1>eyelashes to shield out excess sweater rained or our skulls

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<v Speaker 1>could have continued to protrude so that they formed a

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<v Speaker 1>ledge above our eyes. Rain or sweat would then drop

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<v Speaker 1>from that ledge, straight away from our faces without going

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<v Speaker 1>into our eyes. For more on this and thousands of

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