Why do we have Eyebrows?

March 13, 2017 / Humans / 0 Comments /
Why do we have eyebrows

Throughout our evolutionary history our body hair has gradually been lost, except for the hair on our heads, and our eyebrows.These bits of hair have remained. Unlike the hair on our heads, our eyebrows do not keep us warm – they are too small for a start, and offer almost no insulation. They do have 2 important roles in the body though.

 

Expression & communication

You may not realise it, but eyebrows are an extremely expressive part of the face. Along with the mouth they can indicate anything from anger, to happiness, or even quizzical. You can move them around a lot, and we innately understand what their different positions mean. Raising both eyebrows for example, show surprise, whereas lowering both eyebrows is often disapproving or angry. You can’t show these emotions easily without the eyebrows! When we looked into pareidolia (seeing faces in object that don’t have faces), it was clear that recognising faces and emotions was a key part of our evolution. Eyebrows are an important part of this! After all, you wouldn’t give someone a hug if their eyebrows are down.

We also use our eyebrows for non-verbal communication. A common type of ‘eyebrow communication’ is a quick eyebrow flash upwards to say “hello“. You may even not realise that you do this, but next time you walk past someone in a hallway, you’ll find yourself doing this gesture. Eyebrows can also be used to emphasise words that are of particular importance. A long raise of the eyebrows whilst saying a word adds emphasis and meaning to that word.

Sure, we could still do these expressions without having hairy eyebrows – but they wouldn’t be half as clear.The expressions would blur into the rest of your forehead. Having hairy eyebrows is important.

 

Protection for the eye

Eyebrows are great for diverting water (particularly rain) and sweat away from the eyes.Their arcing shape over the eye, along with the horizontally laying hairs are perfectly designed to drain any water that would go in your eye, down the side of your face. It isn’t so important now we have umbrellas, coats, and spend all our time indoors, but getting water in your eyes makes doing any task difficult. Our eyes are one of our most sensitive senses, and we rely on them quite heavily.

 

Summary

Eyebrows are not one of evolution’s strange quirks – they have a role, and it is still valuable today. Eyebrows are important for expressing emotions and help us to communicate better by helping to add meaning and emphasis to words. They also fulfil a more practical role, and prevent water and sweat from getting into your eyes. Eyebrows are great!

Image courtesy of Jon Colller.