What is the main function of the eyebrows?

The Primary eyebrow function Is to protect the eyes from sweat, rain and even sunlight. Its arched shape allows to divert the course of the water or sweat that goes down the forehead, keeping the eyes free of external substances (Squezze, 2013).

For millions of years the human body has evolved, eliminating the majority of villi present in it. If the presence of the eyebrows were not necessary, they would have disappeared.

Eyebrow function

However, their function is considered to be so important that, if not, humans would have developed other protection mechanisms such as longer eyelashes or more prominent foreheads.

The eyebrows, keep the eyes free of moisture, in this way help people to have better visibility. Similarly, eyebrows help prevent salt-related discomfort when sweat is drawn into the eyes (Contributor, 2015).

Apart from the protection offered to the eyes, eyebrows play a key role in nonverbal communication of emotions. Its movement and gesture allows you to read what a person is feeling, whether astonishment, anger or curiosity.

Historically human beings have attached great importance to the eyebrows, as they are one of the most characteristic features of the face. Culturally, eyebrows are considered to be more attractive than others, and many people spend time and money on eyebrow care (DeMello, 2012).

The functions of the eyebrows are considered biological, aesthetic and cultural, as they are necessary to protect the eyes from moisture, to recognize people based on their facial features and denote certain beauty canals established by different cultures.

The functions of eyebrows for survival

There are numerous ways in which the eyebrows may have helped the survival of the first men. By shielding their eyes from the rain, the first men were able to see more clearly on the horizon, being able to recognize possible shelters.

Similarly, by keeping sweat and moisture away from the eyes, they had better visibility to run and protect their lives from potential threats (HowStuffWork, 2008).

In the case of the first men, these had to evade multiple predators. It is possible that, in the process of fleeing from a predator, the men had sweat running down their faces. The eyebrows, in these situations, prevented that sweat from falling into the eyes, giving them the possibility of having a good visibility and escape.

It is also believed that, in the process of natural selection, they had a better chance of surviving those hominids with eyebrows, over those who had no eyebrows.

Some scientists argue that if the eyebrows disappeared during the evolutionary process, the man would have developed other features that would protect his eyes, such as thick, long eyelashes or prominent foreheads that keep moisture away from the eyes.

Protection of light

Eyebrows also have the function of protecting the eyes from light. In this way, they represent a protection that prevents the sun from directly illuminating the eyes.

Reflections and intense flashes of light are mitigated by the eyebrows, thus preventing the person from being blinded by intense light (Agarwal, Agarwal, & Apple, 2002).

Many American football players use"false eyebrows"to attenuate the intensity of light during a game. This is how they paint small dark stripes on their faces, which allow the light to deviate and have a better visibility of the field during the game.

Recognition of facial features

According to a study led by neuroscientist Javid Sadr and colleagues at MIT University, eyebrows are crucial for the identification of easy traits, and this is one of the main reasons why they have not disappeared from the human body. They indicate that a face without brows is like a city without points of reference (Sadr, 2003).

The premise of this study was to assert that eyebrows make faces recognizable. This way, the volunteers were invited to identify fifty faces of celebrities, including presidents of the United States and Hollywood actresses.

The photos of the faces of these celebrities were digitally altered, eliminating in some the eyes and in others the eyebrows.

The result of this study showed that 60 percent of the time, people could recognize celebrities whose eyes had been digitally removed. However, only 46 percent of the volunteers were able to identify celebrities whose eyebrows had been removed.

The conclusion of the study states that eyebrows are as important as the eyes to recognize people. If a person changes the color of the eyes, injects Botox or collagen, or wears a pair of sunglasses, it would be easy to recognize. On the other hand, if this person were to shave his eyebrows, it would be very difficult to recognize it with the naked eye.

Sadr points out that the fundamental reason for eyebrows to be key in facial recognition is that they themselves help the expression of emotions and feelings. The eyebrows along with the lips may be the most expressive parts of the body in terms of non-verbal language.

On the other hand, the shape of the eyebrows also quickly reveals important information about the person's age, gender and other characteristics. In this way, the women's eyebrows tend to be a few millimeters above those of men.

Also thick-set eyebrows in males are characteristic of"alpha males", while thin, arched brows are common in young, stylized females (Pincott, 2011).

The eyebrows also show traits of the culture, as you can see in Renaissance art that people shaved their eyebrows as a sign of beauty, which is why it is assumed that the Mona Lisa was a beautiful woman because his eyebrows were shaved . Similarly, during the eighteenth century in America, people preferred to raise the arch of their eyebrows using a gray mus.


  1. Agarwal, S., Agarwal, A., & Apple, D. J. (2002). Eyebrow Esthetics. In S. Agarwal, A. Agarwal, & D. J. Apple, Textbook of Ophthalmology, Volume 1 (Page 647). New Dehli: Jaypee Brothers.
  2. Contributor, N. N. (Director). (2015). Why Do We Have Eyebrows and Eyelashes? [Motion Picture].
  3. DeMello, M. (2012). Facial Features. In M. DeMello, Faces around the World: A Cultural Encyclopedia of the Human Face (Pp. 129-131). Santa Barbara: ABC Clio.
  4. (2008, February 25). How Stuff Work - Health . Retrieved from Why do we have eyebrows?: health.howstuffworks.com.
  5. Pincott, J. (2011, July 4). Psychology Today . Retrieved from The Real Purpose of Eyebrows?: psychologytoday.com.
  6. Sadr, J. (2003). The role of eyebrows in face recognition. Perception , 285-293.
  7. Squeeze, H. (2013, November 16). Future BBC . Retrieved from Why do you have eyebrows?: bbc.com.

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