Why do we have eyebrows and eyelashes?

If you’ve ever sweated through a hot yoga class and not gone blind in the process, you’ve got your eyebrows to thank. And if a rogue bug has ever almost dive-bombed into your eye but got stopped at the vision gates, give your lashes a clap. 

Eyebrows and eyelashes aren’t just there to frame your face for selfies — they’re low-key legends of the eye world. Evolution handed them down because squinting through sweat and grit isn’t exactly a survival flex.

We have eyebrows and eyelashes to:

• Keep out unwanted guests: Think dust, sweat, sand, and whatever pollen is doing in your neighborhood this week.

• Help you communicate without saying a word: Ever raised an eyebrow and shut down a whole conversation? Exactly.

• Add to your aesthetic appeal: Humanity didn’t whip up the microbladed brow for no reason.

• Protect the windows to your soul (aka your corneas): Lashes and brows help maintain eye health, moisture, and visibility.

Are they unique to humans? Not entirely — mammals have variants — but no one’s doing it quite like us. Let’s get into the science, the symbolism, and the silent protection baked right onto your face.

The difference between eyebrows and eyelashes

Okay, yes — one is on your brow bone and one’s hugging your eyelid. But functionally, they’re both security guards for your eyes, just stationed at different doors.

• Eyebrows: Your fuzzy arches reroute sweat and water away from your eyes. Their angled shape is a rain gutter with attitude. 

• Eyelashes: These fine, curved hairs act as a first-alert system. When something (dirt, wind, your cat’s tail) gets too close, lashes trigger your blink reflex — aka your natural defense against tiny enemies.

Brows are passive protectors and communication tools. Lashes are active sensors, like motion detectors for your eyeballs. 

What are eyebrows for?

Eyebrows are the bodyguards you didn’t know you had. They reroute moisture (sweat, rain, you name it) around your eyes so it doesn’t drip into your line of vision. 

But that’s not all:

• They’re nonverbal icons. Brows help you show shock, sass, suspicion, or sympathy without saying a word.

• They define your face shape. A strong brow can sharpen features, soften angles, and frame your eyes better than a gallery spotlight.

• They’re culturally significant. From Cleopatra’s elongated arches to the 2016 Instagram block brow — we don’t talk about her — brows have shaped beauty trends for centuries.

And yes, they can be tweezed, threaded, laminated, tinted, bleached, and tattooed. Some of that enhances their function, others not so much. (Laminated brows may repel judgment.) 

As for other mammals, some have fur above their eyes, but humans are the only ones who evolved eyebrows with expression, sweat control, and the ability to communicate “really?” without saying a word.

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What do eyelashes do?

Lashes are your eyes' VIP security rope. They guard the most sensitive surface on your body, batting away dust, debris, and incoming flying objects. Think of them like tiny black belts in eyelid karate.

Here’s their full resume:

• They keep things out. Dirt, smoke, bugs, allergens — lashes help you blink them away before they crash the corneal party.

• They sense danger. Even the lightest touch can make you blink. That’s no accident — it’s survival. Lashes help you react faster than your brain can think “ew, no.”

• They make your eyes pop. Long, dark lashes draw attention to the eye. It’s evolutionary and editorial.

Now, let’s talk enhancements. Mascara is fun. Lash lifts and extensions are glamorous. But beware. Heavy false lashes or sticky adhesives can clog follicles or cause lash fallout. (Yes, lash baldness is real, and it’s tragic.)

Are humans the only ones with lashes? Nope. Camels have legendary lashes. (For real — they evolved in desert storms.) But humans took it a step further, giving ours jobs and beauty campaigns.

The purpose of eyebrows and eyelashes

Eyebrows and eyelashes are like the behind-the-scenes crew of your face — quietly saving your eyes from chaos while helping you express a very specific kind of sarcasm.

Together, they:

• Keep your eyes safe from sweat, particles, UV rays, and full-on insect ambushes.

• Shape how you express emotion, from raised-brow “hmm”s to flirty lashes that blink in Morse code.

• Boost your appearance, naturally or cosmetically. (They’re a canvas and a shield.)

They’re functional, fashionable, face-framing, and flutter-tastic. They’re your eyes’ ride-or-die.

Keep your lashes lush and brows bold

You don’t need to overthink your eyebrows and eyelashes, but a little appreciation goes a long way. They’re working hard for you every single day.

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FAQs

We're not playing twenty questions here, but these might answer a few lingering curiosities. 

Can you lose your eyelashes or eyebrows?

Yes, but don’t panic. Stress, over-plucking, certain medical conditions, or heavy-handed extensions can all lead to shedding. Most hair grows back within weeks to months.

Are thick eyebrows better for protection?

Generally, yes, more density means more barrier. Thicker brows do a better job of diverting sweat, rain, and glitter fallout (you know, in case of spontaneous fabulousness).

Do false lashes protect your eyes?

Not really. They may look lush, but they don’t have the same reflex function. In fact, poorly applied falsies can block airflow and trap irritants. Wear them responsibly, lash queens.

Original publish date: 2/24/2022

Updated date: 9/17/2025