What is a brow ridge? Unpacking the supraorbital structure

September 30, 2025 •

4 min read

A bony protrusion known as the brow ridge, or supraorbital ridge, was a defining characteristic of our early human ancestors and is far more pronounced in species like Neanderthals than it is in modern humans. Located directly above the eye sockets, this anatomical feature varies significantly in size and prominence among people today.

Quick Summary

The brow ridge is a bony prominence above the eye sockets that differs between genders and human ancestors. It's a structural remnant of evolutionary changes but can also be linked to certain medical conditions or aesthetic goals.

Key Points

Bony Structure: The brow ridge is a bony crest on the frontal bone above the eye sockets and is also known medically as the superciliary arch.
Sexual Dimorphism: Influenced by hormones, brow ridges are typically more pronounced in males and less defined in females, contributing to different facial contours.
Evolutionary Remnant: While large brow ridges were characteristic of archaic humans like Neanderthals, they are a diminished feature in modern humans, potentially linked to the evolution of mobile eyebrows for communication.
Medical Indicator: An abnormally prominent brow ridge, known as frontal bossing, can sometimes be a sign of underlying medical conditions such as hormonal or genetic disorders.
Cosmetic Procedures: For those seeking aesthetic changes, permanent surgical procedures like brow bone reduction can be performed to reshape the forehead and brow area.

The Anatomy of the Brow Ridge

The brow ridge is a crest of bone on the frontal bone of the skull, positioned just above the eyes. Its medical term is the superciliary arch, and it serves as a division between the forehead and the eye socket's roof. The smooth, flat area between the arches, where they meet above the nose, is called the glabella. While the ridges arch over each eye in modern humans, in other primates, they are often a continuous, straight bar of bone. These bony arches provide a degree of mechanical protection for the eyes. The underlying frontal sinuses, air-filled spaces behind the ridges, also influence the forehead and brow ridge's appearance as they grow and pneumatize.

Brow Ridge vs. Forehead

It's important to distinguish the brow ridge from the overall forehead. The forehead is a much larger area that makes up a significant portion of the face, with the brow ridges defining its lower border. In profile, a prominent brow ridge creates a noticeable break or angle between the forehead bone and the area directly above the eyes, while a less prominent ridge allows for a smoother, more vertical forehead. This subtle difference contributes significantly to an individual's overall facial appearance.

Sexual Dimorphism and Hormonal Influence

The size and shape of the brow ridge are one of the most visible examples of sexual dimorphism in the human skeleton.

Males: Higher levels of testosterone during puberty often lead to a more pronounced brow ridge, along with a more prominent jaw and chin. This can result in a more angular facial structure and a deeper-set eye appearance.
Females: Women tend to have a flatter, more vertically oriented forehead and a smoother, less prominent brow ridge. This is influenced by different hormonal levels during development.

Evolutionary Roots and Changing Function

The prominent brow ridge seen in our ancient ancestors, like Neanderthals and Homo heidelbergensis, has long fascinated anthropologists. Several theories exist regarding its evolutionary purpose:

Structural Reinforcement: An early theory suggested the large ridges acted as a buttress to reinforce the face against the stresses of chewing, though recent analysis has challenged this.
Social Signalling: Another theory suggests that the prominent ridges were a signal of dominance or aggression, particularly in archaic humans.
Modern Eyebrows: As the brow ridge receded in modern humans, our flat, vertical foreheads allowed for greater mobility and expressiveness of our eyebrows. This enabled more complex and subtle emotional communication, which was crucial for developing the extensive social networks that contributed to our species' survival.

When Prominence is a Medical Concern

While most variation in brow ridge size is normal and genetic, an abnormally prominent forehead, known as frontal bossing, can be a sign of an underlying medical condition. A doctor may identify this condition in infancy or early childhood.

Conditions associated with frontal bossing include:

Acromegaly: A chronic hormonal disorder caused by excess growth hormone.
Basal cell nevus syndrome (Gorlin's syndrome): A rare genetic disorder.
Cleidocranial dysostosis: A condition affecting the teeth and bones.
Hurler syndrome: A metabolic disorder that causes skeletal abnormalities.
Pfeiffer syndrome: A syndrome causing premature skull bone fusion.
Russell-Silver syndrome: A growth disorder associated with a prominent forehead and triangular face.

Cosmetic and Surgical Options

For those who are bothered by a very prominent brow ridge, cosmetic and surgical options are available. Brow bone reduction, also known as forehead contouring, is a permanent surgical procedure that reshapes or reduces the size of the brow bone.

Commonly used surgical techniques include:

Type I (Shaving): Using a specialized burr to shave down the outer surface of the brow bone. This is suitable for minor reductions.
Type III (Reconstruction): Removing the bone above the frontal sinus, reshaping it, and reattaching it. This is used for more significant reductions.

This type of procedure is commonly performed as part of facial feminization surgery (FFS) to achieve a softer, more feminine appearance. For more information on brow ridge reduction, consider consulting a board-certified plastic surgeon. You can also review resources like those available from institutions specializing in such procedures.

The Functions of the Brow Ridge: A Summary

Across different stages of human evolution and today, the brow ridge serves a variety of purposes. Here is a brief overview of its functions throughout history:

Structural Support: In early hominins, the robust brow ridges were once thought to help dissipate the mechanical stress of chewing.
Protection: The bony crest provides a degree of physical protection for the eye sockets from blunt force trauma.
Protection from Elements: The brow ridge and the eyebrows that grow on it help to divert sweat and precipitation away from the eyes.
Sexual Display: In archaic humans, prominent brows may have served as a form of social display or signal of dominance.
Aesthetic and Communicative Function: In modern humans, the reduction of the brow ridge allowed for more expressive eyebrows, which play a crucial role in non-verbal communication.

Comparative Characteristics: Prominent vs. Soft Brow Ridges


Characteristic	Prominent Brow Ridge	Soft Brow Ridge
Associated with	Higher testosterone levels	Lower testosterone levels
Typically seen in	Males	Females
Forehead Profile	Creates a noticeable angle or slope	Appears smoother, more vertical
Eye Appearance	Often creates a deep-set eye look	Allows for a more open eye area
Historical Context	Common in ancient hominins (e.g., Neanderthals)	Predominant in modern humans
Cosmetic Alteration	Can be surgically reduced	Can be surgically enhanced

Conclusion

The brow ridge is more than just a bony feature of the skull; it's a marker of our evolutionary journey, influenced by hormonal and developmental factors. While its size and prominence vary naturally among individuals, it also serves as a visible sign of specific medical conditions in rare cases. For those concerned about its appearance, cosmetic surgery offers a permanent solution to alter its contour. Ultimately, understanding what is a brow ridge provides insight into human anatomy, history, and the subtle facial differences that make each individual unique.

Frequently Asked Questions

Its original purpose is debated among researchers, with theories suggesting it reinforced the skull, protected the eyes, or displayed social status. In modern humans, its primary function is protective and aesthetic.

A more prominent brow ridge is typically associated with male facial features, as it is influenced by testosterone during puberty. However, its prominence varies greatly among individuals, regardless of gender.

While most variation in brow ridge size is normal, an abnormally large brow ridge, referred to as frontal bossing, can be a symptom of certain medical conditions like acromegaly or genetic syndromes. A medical professional should be consulted if there is concern.

The size and shape of a brow ridge are determined by the underlying bone structure, which cannot be altered through natural means like exercise. Surgical intervention is the only way to permanently change its size.

The brow ridge was much larger and more prominent in our ancient ancestors, like Neanderthals. Its reduction in modern humans may have been an evolutionary adaptation that allowed for more expressive eyebrow movements, aiding in social communication.

Yes, surgical reduction of the brow bone is a permanent procedure. The bone removed or reshaped during the surgery will not grow back.

Yes, surgical techniques vary depending on the patient's anatomy and desired outcome. Common approaches include shaving the bone, or, for more significant changes, removing, reshaping, and replacing a section of the bone.