Vestiges of Evolution: Exploring the Mysteries of Human Anatomy

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In our intricate human anatomy, every body part holds its own significance, even those that have been categorized as seemingly obsolete due to evolutionary changes. Among these often-dismissed body parts are the auricular muscles in the ear.

Some individuals possess the rare ability to wiggle their ears ever so slightly. These auricular muscles were once integral for tracking sounds. These muscles are found in various animals, including dogs, cats, apes, and monkeys. In the past, our ancestors could manipulate their ears to some extent in response to sounds. However, this ability has diminished over time due to evolution, and these muscles are now considered vestigial. While they may not visibly move in response to sounds, studies have revealed that the brain areas associated with these muscles exhibit activity when we hear sounds.


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Another body part you might have not heard of, or do not know about is the Plica Semilunaris referred to as Third Eyelid. It is a vertical line found in the medial side of the eye area. This eyelid is common with reptiles, cats, dogs, and so many other animals and it is referred to as the Nictitating membrane (membrana nictitans) which is a moistener. While we do not have this membrane in any of our close relatives or in ourselves but we have the Plica Semilunaris and we have enough moist in our eyes for additional moisteners.

Wisdom teeth, or third molars, are frequently considered unhelpful due to their propensity to grow misaligned and necessitate removal by dentists. Evolution has led to changes in our dietary habits, as we are no longer grinding uncooked plants and have adopted an omnivorous diet. This dietary shift has prompted alterations in our facial structure, including a flatter face and a pronounced chin unique to humans. As a result, our molars have become compressed, and there is often insufficient room for the eruption of wisdom teeth, leading to various dental issues.

Arrector Pili Muscles which are muscles responsible for goosebumps effects causes the skin to stand erect when stimulated such as when you are responding to some kind of threats. In animals, this erection of hair helps them increase in size since they are hairy but with humans, we are not too hairy, so having goosebumps doesn't actually increase our size.


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The appendix, a small pouch extending from the cecum, has long been dismissed as a vestigial structure, believed to have lost its function over time. Due to its potential for inflammation, it was also considered a potential health risk. However, recent research has challenged these assumptions. It turns out that the appendix plays a role in housing beneficial gut bacteria, helping protect against harmful bacteria and aiding in overall gut health.


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Plantaris Muscle is a muscle in the leg that is now vestigial. The plantaris muscle runs from the femur then have a separate tendon which is larger in apes with the primary function to assist the plantarflexion of the ankle, which means it helps point the foot downward. The plantaris muscle is not present in everyone and has lost its previous function and has become thin and weak.

Our bodies are a testament to the ongoing process of evolution. While some body parts may seem obsolete or vestigial in the context of modern human life, they often retain traces of their original functions and continue to contribute to the complexity of our anatomy. These "relics" of our evolutionary history remind us of the fascinating journey our species has undertaken.

Reference

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I think Coccyx a.k.a the Tailbone is another structure that is also considered to be vestigial in humans. However, sometimes I think maybe we just need time to figure out the uses of these structures just like in the case of the Appendix.

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