Why Do Humans Have Eyebrows? - Jae Pak MD Medical

Why Do Humans Have Eyebrows?

We take the human body and all its functions for granted. Since most of these processes happen behind the scenes, most of us don’t even think twice about what keeps us ticking and healthy. 

But even features that are front and center, like eyebrows, have some mystery of their own. Let’s discuss why humans have eyebrows and what you can do to maximize their form and function moving forward. 

Some Background on Eyebrows

What exactly are these horizontal strips of hair meant for, and how do they help us in everyday life? Since the human body doesn’t come with an instruction manual, we have to piece together the answer through reason and evidence, but we think we’ve reached a satisfactory conclusion. 

Let’s list some facts and stats that you might not have known about this unique facial feature. 

First off, how many hairs make up the typical eyebrow? Research shows that the average brow contains roughly 250 hairs, meaning that you may have as many as 500 brow hairs on your face at a given time. 

As you may have noticed, eyebrow hair is slightly different from the hair on your head or other areas of the body. It tends to be thicker, somewhat coarser and maintains the unique shape and “grain” of your brow. 

While you might get the occasional rogue brow hair, they typically grow in the same direction and “work together” to create a cohesive shape that complements and frames your face.

Brows have a slightly different life cycle as well. The lifespan of human hair can range anywhere from two to seven years, while brow hairs come and go in just a few short months. By the time an eyebrow hair falls out, another one emerges quickly to fill its place.

Finally, eyebrows experience many of the same aging signals as our head hair and other systems of the body. As we age, we see brow hair become longer and unruly. Even the density and consistency of the entire brow may decline slightly. 

You may notice eyebrow hair turning gray after a certain age, as the pigment in the follicles gradually diminishes, just like head hair. Of course, every pair of brows is different. We all have unique strengths and weaknesses to address when achieving our desired look. 

Protective Reasons for Brows

We have a better idea of how eyebrows work and why, but now it’s time to see how brows have helped the human race survive for many thousands of years. Yes, scientists firmly believe that brows have multiple evolutionary purposes that can be explained through genetics and natural selection. 

Here’s the first batch of reasons why we have brows related to protection and safety. 

Sun Protection

If nature were to make a pair of natural sunglasses for the human body, they’d look a bit like eyebrows. Lashes and lids offer added layers of sun safety, but brows do a lot of the heavy lifting to keep those harmful UV rays at bay. 

Brow hair is arranged precisely in the right location to dampen some of the harsh UV light we encounter daily, helping us to see more clearly in sunny conditions. Without brows, we might just be blinded by the light, even when the sun isn’t shining directly.

Wind and Water Protection

When the wind starts blowing, there’s no telling what kind of dust and debris might end up in the worst possible place — your eyes. 

Our faces are somewhat aerodynamically designed to move through space with ease, but our eyebrows soften the harsh impact of wind and whatever comes with it.

The next time you find yourself in a windy situation, notice how you naturally furrow your brow to get the most amount of natural protection from your brow hair. The same goes for when we sweat or get soaked by rain. It’s evolutionary biology in action.

Warmth and Insulation

What did our ancient ancestors do when the sun went down and temperatures dropped? It got cold quickly without HVAC systems and wool sweaters. Therefore, those with bushy brows were more insulated from the cold, which could have helped them to survive.

It may not seem like much, but every bit of warmth retention counts when humans are in survival mode. If your eyebrow hair can lock in that extra heat, it’s a big bonus for your temperature regulation. 

This also explains why people from northern regions of the world tend to have more defined and full brows than people who live closer to the equator.

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Aesthetic Reasons for Brows

It’s clear that brows do more than meet the eye in a biological sense, but there are also social, aesthetic, and behavioral reasons for why we have these hair-bearing strips of skin above our eyes. 

Here are other factors that may have influenced the development of human eyebrows over time.

Facial Recognition

Back in the early days of humanity, rapid facial recognition was vital to survival. You needed to be able to tell friends from foes in a flash. It might have meant the difference between life and death.

Nowadays, the stakes aren’t quite as high, but we are still wired to see eyebrows as one of the quickest methods of facial recognition as we navigate social environments. In fact, brows are one of the most definitive features among people who may otherwise look quite similar. 

Just search for an image of someone without eyebrows. It immediately becomes more difficult to recognize the person without the brows that make them who they are.

Nonverbal Communication 

Even the slightest eyebrow movement can tell a thousand words, especially among people you know well. Eyebrows indicate emotions as well as any other aspect of body language. You can quickly learn a lot about what a person thinks by observing the way their brows move.

For instance, a slight brow raise might indicate inquisitiveness, while a downward angled brow shows that someone may be concerned or even feel upset. To improve your poker face, keep a stiff brow so nobody can read you.

Beauty and Attraction

Healthy and full brows may indicate a person is a fit and a suitable mate. This basis of natural selection can help explain why humans developed how we did through the millennia. But there is more to eyebrows today than in the past.

Neglected eyebrows are a sign of the past. Brows have now become one of the most popular makeup categories for women, while many guys have started to take this face-changing aspect of grooming more seriously. 

If you can improve your brows to help improve your social scene, why not put in that bit of extra effort?

Personality Prediction?

In the pseudoscientific study of physiognomy, the assertion is that the shape and structure of a person’s face can tell us about their personality. This isn’t a serious point of study in modern medicine, but it does ring true when deciding what brow shape we wish to achieve.

For example, some people with naturally downward-pointing eyebrows might appear less trustworthy, even if their actions suggest otherwise. As a result, it’s not uncommon for people to try to change the shape of their brows to better reflect who they are.

Getting Better Brows: 5 Tips To Try Now

There’s so much to learn about brows, what they do, and the purposes they serve. Now, let’s finish off with our five top tips to keep your eyebrows strong, healthy, and looking their best. That way, you get all the benefits we’ve outlined today.

1. Regrowth and Optimal Health

With so much emphasis on achieving the perfect brow through cosmetics, we must not forget that the best-looking and longest-lasting brows are healthy and natural.

If you’ve noticed some thinning through the years, take a few months off from plucking and tweezing to regrow your brows. Start back from square one. A healthy lifestyle will never harm your brows. In fact, it could help them grow longer and stronger. 

This means cleaning up your diet and maintaining good habits, like keeping stress to a minimum. 

2. Maintain Color and Volume

The color of your brows is almost as important as the volume when going for that full, natural look. If you need to use fillers and dyes in the meantime, that’s fine, as long as you don’t rely on them too heavily.

Experts recommend using a slightly lighter shade for your brows since going too dark can create a less-than-natural look. If you find yourself continually penciling in your eyebrows, you may want to speak with Jae Pak, M.D., to learn about eyebrow restoration options.

3. Consider New Treatments

Some brows have lost too much volume and shape through the years, whether from genetics or external factors. With today’s brow transplantation procedures, you can dramatically restore your brow shape and coverage with FUE techniques from proven doctors.

Connect with Dr. Jae Pak today to see if a brow transplant is right for you.

Your Brows, Your Way

Eyebrows do more than keep the sun out of your eyes. These face-framers help you better navigate the social scene. You don’t have to live with thinning brows or commit to a lifetime of pencils and fillers. 

Learn the best way to take charge of your eyebrow health and feel more like yourself again. 


Why Do We Have Eyebrows? | Ask Dr. Universe

How to Grow Your Eyebrows | Women’s Health

Eyebrows, Eyelids, and Face | Ento Key

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