1. Male Nipples Male nipples have been a source of comedy and intrigue over the years as more and more people come to realize that they really don't serve any functional purpose. Men have nipples simply because they could have been females in the early stages of development. In the first two months in the womb, both men and women develop the same way. If a Y chromosome is present, the fetus will start producing testosterone, and subsequently male reproductive organs. But nipples have been left in the male genome simply because having them isn't a bad thing or a good thing. They just are. 2. The Tailbone Most humans have mastered balance by now, so having a tail is no longer necessary. Almost all mammals develop a tail at some point during their growth cycle, but not all of them still have it by the time they're ready to pop out of momma. Humans, for example, have some semblance of a tail around five to eight weeks after being conceived, but it simply becomes part of our vertebrae as we continue to develop. If you really want to see humans with tails, a quick Google search will satisfy your intrigue. 3. Wisdom Teeth As a person who has gotten his wisdom teeth removed, and had a terrible time with the recovery process, this evolutionary trait that got left behind can be somewhat tedious. As humans jaws became smaller over time, our mouths simply ran out of room for our wisdom teeth, causing many people to have to get them surgically removed at some point in their life. One out of every five people suffers from 'dental crowding,' a term used to describe more teeth than is necessary. The widely accepted theory is that human mouths became smaller due to a change in how we consume food. Once we stopped needing to chomp through raw meats and vegetables, we began to eat differently. 4. The Appendix The appendix, which is located in between the small and large intestines, serves absolutely zero function in the digestive process. Some scientists think that it might have served a function when human diet revolved largely around plants. Now, many people simply have it removed because it can become infected and rupture. 5. The Third Eyelid If you look closely at your eyes, you can see an extra bit of skin lying close to your nose. This skin, dubbed the 'plica semilunaris,' serves virtually no purpose for humans anymore. However, birds and reptiles have a similar third eyelid that is translucent and is pulled over the eye for extra protection or moisture. Source
