Speaker 1: Welcome to brain Stuff from house stuffworks dot com where
Speaker 1: smart happens. Hi Am Marshall Brain with today's question, why
Speaker 1: do human beings have eyebrows? Scientists aren't entirely sure why
Speaker 1: we kept this hair, but they have a pretty good guess.
Speaker 1: We know that eyebrows help keep moisture out of our
Speaker 1: eyes when we sweat or when we walk around in
Speaker 1: the rain. The art shape diverts the rain or sweat
Speaker 1: around to the sides of our face, keeping our eyes
Speaker 1: relatively dry. The most obvious advantage of this is that
Speaker 1: it lets us see clearly when we're sweating a lot
Speaker 1: or when we're out in the rain. Without eyebrows, getting
Speaker 1: around in these conditions is a little more difficult. Diverting
Speaker 1: this sweat away is also good because the salt and
Speaker 1: sweat irritates the eyes, making them sting a little. Eyebrows
Speaker 1: are a very significant aspect of our pearance. They are
Speaker 1: one of the most distinctive features that make up our faces,
Speaker 1: and we pay a lot of attention to them. We
Speaker 1: think of some types of eyebrows as attractive and some
Speaker 1: is unattractive, and many people spend as much time preening
Speaker 1: their eyebrows as they do applying makeup to their eyelashes
Speaker 1: or lips. Eyebrows are also one of our most expressive
Speaker 1: facial features. One of the clearest ways to tell somebody
Speaker 1: what you're thinking is to simply move your eyebrows up
Speaker 1: or down. We all know what different eyebrow positions mean,
Speaker 1: so eyebrows obviously serve a lot of functions for our faces.
Speaker 1: There's beauty, nonverbal communication, distinctive appearance, the whole water shedding thing.
Speaker 1: But most scientists are inclined to believe that if we
Speaker 1: didn't have eyebrows, something else would have evolved to help
Speaker 1: the situation. For example, humans could have developed incredibly thick
Speaker 1: eyelashes to shield out excess sweater rained or our skulls
Speaker 1: could have continued to protrude so that they formed a
Speaker 1: ledge above our eyes. Rain or sweat would then drop
Speaker 1: from that ledge, straight away from our faces without going
Speaker 1: into our eyes. For more on this and thousands of
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