You might have noticed that some people have a tiny hole at the top part of their ear, and you think, why would anyone pierce their ear in that area? Well, they are not actually not ear piercings that your friend got when he or she got drunk. When I noticed mine when I was a kid, I thought I had mermaid gills and I was adopted by my parents. BUT, that tiny hole is actually a congenital disorder called preauricular sinus. It is caused by the developmental defects of the first and second pharyngeal arches. In mammals, they go on to form the structures of the head and neck, but in fish they also help develop into their gills. Although they are harmless, preaucricular sinuses can be infected. If needed, they can be excised by surgery.
According to a study by PMC, 0.1 percent of the population have it in the US, 0.9 percent in the UK, and as many as 4 to 10 percent in Asia and parts of Africa. In South Korea, that figure could be as high as 5 percent, and it’s most common in people of African or Asian descent.
In 1864 it was already documented by Van Heusinger and was also studied by a biologist named Neil Shubin and said that “these holes could be an evolutionary remanant of fish gills” according to Business Insider. That may just be a theory but nevertheless, when you think that we still have tailbones and appendixes from our evolutionary ancestors, it sure is not impossible.