The fact of our descent from a hairier and more agile hominid is present in our current body structures. We retain many traits and behaviours that clearly indicate that we used to be different and live in different ways, and in different environments. Our primate ancestry is apparent and obvious in the Palmar grasp reflex of infants, our sinuses and the vestigial elements of our ears, and plica semilunaris- a third eyelid usually found in birds and reptiles is also present in the human body, showing us the exact line of descent. Here are 5 vestigial traits in humans.
The tailbone is exactly what it sounds: a bone that used to support the tail that humans had back in the day. The coccyx is located on the bottom, just above the butt, exactly where our closest primate relatives have their tails. This tail fully develops during our embryonic phase, but is later re-absorbed into the body.
This organ is one of the most well-known examples of vestigial traits. The appendix is probably much smaller now than it used to be, and signifies a turn towards eating more meat and less cellulose. These organs used to store plant based foods rich in cellulose and helped break them down, but now that we have agriculture and nutrient rich foods, having one is no longer important, so it has begun to shrink, and in the future will probably be completely gone.
Ever wonder where goose bumps come from? They are not a vestigial trait of a birdlike ancestry, I can tell you that much. Arrector pili are the mechanisms that make your hair stand on end, and it is a common trait among furry forest creatures, which humans, at one point, used to be. This function of the human body served to make the hairs stand up and trap the air movements, and it also made evaporation of sweat possible, and thus served as a cooling mechanism. Since we are no longer covered in fur, this trait has outlived its usefulness, and is now only useful or embarrassing, in a social setting.
Tonsils are constantly debated by biologists and evolutionary theorists. They serve as a part of the immune system, but they frequently only contribute to infection, and are unnecessary to the healthy functioning of the immune system, and thus probably served a more important function earlier. Whether they are completely vestigial or not remains to be seen, as no conclusive evidence exists.
Our skulls used to be larger, and our brains somewhat smaller. The existence of wisdom teeth attests to this; they do not have enough room to erupt into the mouth, meaning they “expect” to come into a larger space, and are frequently impacted for lack of space. These extra teeth have outlived their usefulness, and are frequently extracted or removed.