Curious Kids: why do we have eyebrows?

Mummy, why do we have eyebrows? — Alexander, age 3, Brisbane.

What a great, eyebrow-raising question, Alexander!

Eyebrows come in a range of shapes, sizes and colours. They help make our faces unique. But there’s more to eyebrows than meets the eye.

Eyebrows help us express our feelings

Our eyebrows say a lot about how we are feeling. We scrunch our eyebrows when angry, and perk them up when surprised.

Moving our eyebrows can also tell people if we’re happy, confused, sad or upset. These expressions help us communicate. So, eyebrows can tell a story without saying a word.

How quickly we move our eyebrows also matters. When we’re sad, we move our eyebrows slowly. When we’re angry, we move them faster. And when we’re happy, we move them the fastest.

Eyebrows protect your eyes

If you have been running around on a hot day, you might notice some sweating on your forehead. The shape of the bones and skin around the eyebrows helps direct the sweat toward the side of our faces. That stops water from running directly into our eyes.

How our eyebrow hairs are lined up, and the direction they grow in, also help protect our eyes from sweat, as well as from dirt, dust and water.

In fact, when dust lands on our eyebrows, we often blink automatically to get rid of the dust. Even if dust lands on one eyebrow, we can’t help blinking both eyes.

Our eyebrows also shade our eyes from bright lights. The eyebrow hairs stick out from our face, which reduces the amount of sunlight entering our eyes.

And when we’ve had a tiring day, or when we’re asleep, eyebrows help us relax our eyes. They reduce strain on our eye muscles and help us shut our eyelids.

Eyebrows form part of our identity

Whether we have big bushy eyebrows, or styled “brows”, our eyebrows play a big part in making us look unique.

They also help us recognise familiar faces. So if we didn’t have eyebrows, we might not so easily recognise our friends or family.

Looking at eyebrows also helps us know if someone’s a man or a woman. That’s because men tend to have thicker eyebrows closer to the eyes, and women have thinner eyebrows higher above the eyes.

And older people, like our grandparents, can have tired or droopy looking eyebrows. That’s because, as people get older, their eyebrow muscles become worn out and gravity pulls them down.

Read more: Curious Kids: why do older adults get shorter?

Eyebrows can be beautiful

Since ancient Egyptian times, people have linked eyebrows with beauty. Men and women used to paint on dark, arched eyebrows with a black powder to show respect to Egyptian gods. Eyebrows were also thought to give people supernatural powers!

Read more: Friday essay: shaved, shaped and slit - eyebrows through the ages

Even today, people tweak the look of their eyebrows. They can remove hairs by tweezing or waxing. They can even dye their eyebrows or tattoo them.

So, next time you look in the mirror, take a closer look at your eyebrows. They tell others how you’re feeling and help protect your eyes. They also play a big part in what you look like and who you are.

Hello, Curious Kids! Have you got a question you’d like an expert to answer? Ask an adult to send your question to curiouskids@theconversation.edu.au