Preauricular sinus — the small hole sometimes found just above the ear — is a congenital anomaly that has puzzled scientists since 1864. Present in a tiny fraction of the population in some countries and far more widespread in others, it is largely harmless but can occasionally require medical attention.
You may have noticed it on yourself or someone close to you: a tiny pit sitting just at the top of the ear, barely visible, easy to mistake for a pore. This small opening has a name, a history, and a surprisingly debated origin story.
The preauricular sinus is a hereditary birth anomaly
The phenomenon was first formally observed by the scientist Van Heusinger in 1864, during the nineteenth century. He described it as a "hereditary birth malformation", meaning it is passed down through families and present from birth. Its medical name is preauricular sinus, from the Latin for "before the ear."
The hole is not random in its placement. Most of the time, it appears on the right side of the head, though it can occasionally occur on both sides. Its supposed function, according to early theories, was to help connect the sounds and resonances picked up by the ears to the brain. That hypothesis has never been proven, but it gives a sense of how early observers tried to rationalize its presence.
The preauricular sinus is hereditary. If one of your parents has this small pit above the ear, there is a meaningful chance you inherited it too.
How common is the preauricular sinus?
The prevalence of this anomaly varies dramatically depending on geography. In the United States, only 0.1% of the population is affected — a negligible share. In England, the figure rises to 1 person in 100. But in certain parts of Asia and Africa, the numbers are strikingly higher, reaching 4 to 10% of the population in some Asian communities. This uneven distribution across the globe reinforces its genetic character and suggests that specific ancestral lineages carry the trait more frequently.
The fish gill theory, a popular but unproven idea
The most captivating explanation for the preauricular sinus comes from Neil Shubin, an evolutionary biologist. His theory proposes that this small hole is a vestigial remnant of fish gills, a leftover trace from an ancient stage of vertebrate evolution. The idea is that during embryonic development, humans briefly pass through a phase that echoes earlier evolutionary forms, and this pit is a relic of that process.
It is a compelling narrative, and it has spread widely in popular science circles. But the scientific community has not validated it. Shubin's theory remains a popular belief, not a demonstrated scientific fact. To put it in context, a similar logic is applied to the coccyx, the small bone at the base of the human spine that is widely considered a vestige of an ancestral tail. Both are treated as evolutionary footnotes, intriguing but not fully explained.
This kind of bodily curiosity tends to capture the public imagination — much like the way body-focused segments of the classic French animated series Il était une fois… la Vie brought anatomy to life for generations of viewers.
When the preauricular sinus becomes a medical concern
For the vast majority of people who have it, the preauricular sinus causes absolutely no trouble. It sits quietly above the ear, unnoticed and benign. But in some cases, it can become a source of real discomfort.
Recognizing the signs of infection
The main risk associated with this congenital pit is infection. When bacteria enter the sinus tract, the area can become inflamed and painful. The warning signs are relatively clear: a change in color around the opening, followed by redness and potentially the formation of an abscess. These symptoms should not be ignored. Anyone who notices this progression — whether on their own skin or that of a child — should consult a general practitioner or a dermatologist promptly.
Just as with other skin-related concerns, early attention makes a significant difference. The same principle applies to many conditions covered in beauty and skincare guidance: catching a problem early limits complications.
Surgical removal as a definitive option
When the preauricular sinus becomes recurrently infected or simply bothersome, medicine offers a clean solution: surgical removal. The procedure eliminates the sinus tract entirely, putting an end to any recurring issues. It is a straightforward option for those who want a permanent resolution, though for the majority of people who carry this anomaly without symptoms, no intervention is ever needed.
If the skin around the preauricular sinus starts to redden or swell, do not wait. An abscess can develop quickly and requires prompt medical evaluation.
A geographic anomaly that raises evolutionary questions
of certain Asian populations carry a preauricular sinus
The stark difference in prevalence between populations — 0.1% in the United States versus up to 10% in parts of Asia and Africa — is one of the more intriguing aspects of this condition. It suggests that the trait was either selected for, or simply maintained, in certain genetic lineages over thousands of years, while remaining exceptionally rare in others.
This kind of variation in physical traits across populations is a reminder of how much human biology still holds in terms of unexplained diversity. Much like the habits and choices that influence visible traits — such as the factors that can accelerate the appearance of white hair — some physical characteristics are written into our genes from the very beginning, inherited quietly and carried without ceremony.
The preauricular sinus is, in the end, a small mark of biological history. Harmless in most cases, medically manageable when it is not, and scientifically fascinating regardless. Whether it traces back to ancient fish ancestors or simply represents a quirk of embryonic development, it has been part of the human story since long before Van Heusinger gave it a name in 1864.
