“Vestgial Structures” are body parts that serve no useful modern function and are vestiges left over from prior forms of the organism. Vestigial structures are clear examples of evolution at work. Here are some examples in humans:
- Tailbone (coccyx). This is supposedly left over from when our ancestors had tails. Its worth noting that humans also have tails during their prenatal development which are absorbed by the body (usually – sometimes human babies are born with tails – here’s a link to a medical journal discussing the range of traits of six different tails removed from babies): https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3263034/
My daughter Audrey last night told me that she wished she had a tail. Don’t we all wish we had tails?
- Goosebumps. This reaction to the cold is left over from when our ancestors had fur. Reading about vestigial organs gives me goosebumps.
- Wisdom teeth. These extra teeth were nice to have with all the plants early humans had to eat to survive. Here’s info from UCSB on this topic: “Until quite recently, our diet included mostly very coarse food, as well as impurities such as dirt and sand. This coarseness would abrade teeth so significantly that they would take up less space in the jaw. Permanent teeth were also frequently lost at an early age, which would create more space in the jaw. Because the diet was so coarse and hard to chew, the jaw itself would develop into a larger bone because of this constant workout. All of these factors would create more space for the wisdom teeth when they came in.” That is no longer the case for many people who need their wisdom teeth removed due to lack of room for them. I had my wisdom teeth removed. I miss them.
- Paranasal Sinuses – it is thought that these sinus cavities used to be lined with odor receptors that gave a heightened sense of smell to our ancestors, which aided survival. They have no real use to us today. They can get infected though which sucks.
- Vomeronasal Organ – a tiny pit on each side of the septum thought to be the remains of a once extensive pheromone-detecting ability.
- Extrinsic Ear Muscles – these muscles made it possible for prehominids to move their ears independently of their heads, as rabbits and dogs do. We still sort of have them which is why you can wiggle your ears (if you practice). I am going to practice wiggling my ears everyday in 2018. I’ll let you know how this goes next year.
- Neck Rib – a set of cervical ribs – possibly leftovers from the age of reptiles – still appear in less than 1 percent of the population.
- Third eyelid – Called the plica semilunaris. A common ancestor of birds and mammals may have had a membrane for protecting the eye and sweeping out debris. Humans retain only a tiny fold in the inner corner of the eye. I wish I had a full third eyelid.
- Darwin’s Point – A small folded point of skin toward the top of each ear is occasionally found in modern humans (I have them). It may be a remnant of a larger shape that helped focus distant sounds. Take your finger and run it along the inner edge of your ear. Near the top you’ll notice a small piece of skin that is almost like a point. I can do party tricks with my Darwin’s point.
- Subclavius Muscle – This small muscle stretching under the shoulder from the first rib to the collarbone would be useful if humans still walked on all fours. Some people have one, some have none, and a few have two. I have 3 subclavius muscles and can crawl faster than I can run. JK.
- Palmaris Muscle – This long, narrow muscle runs from the elbow to the wrist and is missing in 11 percent of modern humans. It may once have been important for hanging and climbing. Surgeons harvest it for reconstructive surgery. I have this muscle which allows me to do a ton of pullups.
- Appendix – This was thought to be a vestigial organ, but now it is thought the appendix serves an important purpose. IFOD on the appendix and its purpose: http://www.theifod.com/it-turns-out-the-appendix-is-not-useless/
My appendix is named Carl.
- Plantaris Muscle – Often mistaken for a nerve by medical students, the muscle was useful to other primates for grasping with their feet. It has disappeared altogether in 9 percent of the population.
- Thirteenth Rib – Our closest cousins, chimpanzees and gorillas, have an extra set of ribs as compared to humans. Most of us have 12, but 8 percent of adults have the extras. I have fourteen sets ribs.