From time to time, a child is born with some peculiar features. Whether it’s multicolored eyes, two extra fingers, or lack thereof, genetics and birth defects sometimes pose some interesting results. Here’s one you may or may not have noticed: preauricular sinuses. As it turns out, some people have odd little holes above their ears. Some of those who possess this interesting feature doesn’t even know what it is, but there’s an explanation.

A preauricular sinus, also known as a preauricular pit, preauricular tract, and preauricular cyst, is a congenital malformation of the preauricular soft tissues.

This small abnormality was first reported in 1864 in a study by a scientist Van Heusinger. It often occurs in front of the upper ear, usually located just between the face and the cartilage of the ear rim. It can occur on one or both sides of the ears.

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What’s the most peculiar about this is that these holes are connected to the sinus tract that runs under the skin with a short or long and complicated path—something that doesn’t typically happen in humans.

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It is known that these pits run in the family; however, they can also occur spontaneously for an unknown reason.

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The prevalence of it varies. They are most common in East Asian populations, with an incidence of 10%, and less common in people of African descent (4%) and Caucasians (0.5%).

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While a preauricular sinus doesn’t appear to affect a person who has it in any way, it sometimes can get infected and require treatment.

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While it isn’t exactly clear why preauricular sinuses occur, one scientist has an idea. According to one evolutionary biologist, Neil Shubin, these holes could be a remnant of fish gills.

As it turn out, humans and fish may have a lot more in common than we think. Shubin, who wrote a book called “Your Inner Fish”, believes that human ears evolved from fish gills. Fascinating, isn’t it?

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