When you think about a congenital malformation, your mind probably thinks of the really obvious stuff: a cleft palate, spina bifida, and microcephaly (you know, the one where a baby is born with a smaller than average head), just to name a few. But some are so small and rare that most people go through life unaware that they even have a condition shared by millions of others.
One example of a harmless, and very peculiar, congenital malformation is a small hole above the ear, usually located in the place where the cartilage meets the face. How often it shows up depends a lot on race: 0.9% of people in the UK are born with it (so, 1 in 100 births), and 4-10% of people in Africa and Asia are born with it. It mostly happens on one side of the face, but 25-50% of the time it shows up on both sides.
The medical term for this small hole is preauricular sinus, and they’re harmless as well as inexplicable. Sometimes, it can become infected, and this worst case scenario is very easy to treat. Symptoms of infection include redness, swelling, fluid leakage and head pain. Most infections can be treated with antibiotics but sometimes if an abscess forms, it requires expert surgery.
The reason why a more intense infection requires surgery is that the ear is surrounded by delicate nerves that can cause a lot of pain if they’re handled the wrong way. This is why surgeons and otorhinolaryngologists are usually the people who deal with a badly infected preauricular sinus.
Originally found by a scientist named Van Heusinger in 1864, specialists are still speculating on what causes this rare and often harmless malformation. Some people, like evolutionary biologist Neil Shubin, believe that the holes are an evolutionary remnant of fish gills.
Some other examples of rare evolutionary remnants (called vestigial traits) are the ability to move our ears, a tendon that protrudes from your wrist and palmar grasp reflex.
Specialists advise strongly against poking, piercing or modifying these small holes because of the how prone they can be to infections.