10 Evolutionary Leftovers In the Human Body that No Longer Serve A Purpose

10 Evolutionary Leftovers In the Human Body that No Longer Serve A Purpose

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Since the first human being started roaming this planet, mankind has come a long way. We have achieved things beyond our ancestors’ imaginations and have made progress in the field of science and medicine. But along the way, some of the traits our ancestors had were slowly discarded, making us completely different from them. However, some of those evolutionary traits or leftovers can still be seen in most of our bodies. These little bits and pieces we don’t really need anymore were once helpful at ensuring mankind’s survival on this planet. Here, we are listing some of those little bits of evidence of evolution you can see on your own body.

1. A vestigial muscle called the Palmaris Longus used to help our ancestors move around the trees. Today, more than 14% of the population doesn’t have this muscle.

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Image: Vox/YouTube

The muscle in our arms called the palamaris longus, is missing in around 10 to 14% of people. According to NCBI, missing the muscle doesn’t make a person weaker. The muscle is a remnant of our ancestors who used forearms for climbing, but today, those without the muscle can grip just as tightly as those with it.

To see if you have it, hold your arm out, palm facing upwards, and close your hand so that you can press your thumb between your middle and fourth fingers. If it’s there, the tendon should pop out of your wrist slightly, similar to the photo above. (source)

2. The little inverted bumps in our ears are called Darwin’s tubercle. They used to help us move our ears around but since we have flexible necks, we don’t need these anymore.

Darwin’s tubercle, evolution, science, facts, life, history
Image: Wikimedia

Darwin’s tubercle is present in about 10.5% of the Spanish adult population, 40% of Indian adults, and 58% of Swedish children. It can be present on both ears or just on one ear. In primates, the Macaca and Papio have been found to have a pointed upper margin of the ear, similar to Darwin’s tubercle in humans. It was originally discovered by the celebrated British sculptor Thomas Woolner, who later informed Charles Darwin about his findings. In The Descent of Man, Darwin (1871:15-17) cited this structure as probable evidence for common ancestry of humans and monkeys. (source)

3. The Plica Semilunaris is that little pink thing at the corner of your eyes. It used to be a third eyelid that would blink horizontally. It’s still present in many animals as shown in the picture below.

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Image: Toby Hudson/Liam Welch

The plica semilunaris is the curvilinear pinkish tissue in each person’s eye, which is believed to be a useless holdover from evolution, a vestigial tissue of the nictitating membrane in other mammals. In the chimpanzee, however—one of the human species’ closest relatives—the plica semilunaris also appears to be vestigial.

Most animals have this unusual feature to protect, clean, moist and conceal the eye from predators. Scientists also discovered several species that had plica semilunaris that were transparent. This not only allows them to protect their eyes but also to enable vision when underground or underwater. It is still unclear as to why the nictitating membrane in humans is not present anymore but scientists believe that the changes in habitat could have rendered the tissue unnecessary. (source)

4. Getting goosebumps when you’re cold or scared is a vestigial reflex that used to raise body hair to make you appear bigger or trap an extra layer of heat for warmth. Some people are capable of activating the process on demand.

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Image: Pixabay

Goosebumps are a physiological phenomenon inherited from our animal ancestors. The process was useful to them but is not of much help to us. When we are cold or threatened, tiny elevations of the skin, caused by a contraction of miniature muscles that are attached to each hair occurs. These contracting muscles create a shallow depression on the surface, causing its surrounding area to protrude. The same process causes our body hair to stand up. According to scientists, the process of raising hair when cold was done by our ancestors to expand the layer of air that serves as insulation, since the thicker the layer, the better the heat is retained.

When scared, the same process takes place to makes the animal look bigger, causing the predator to back off. Goosebumps are caused due to a stress hormone called adrenaline. In both humans and animals, adrenaline is often released when we feel cold, afraid or experience a strong emotion. (source)

5. Wisdom Teeth are a nuisance for us today because of our diet. Our ancestors diets were different and consisted of mainly meat and branches. The extra teeth helped them grind down different kinds of things.

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Image: Authority Dental

Wisdom tooth removal is common practice in countries such as the United States and Australia. The process is already scary enough and also painful. So, why do we have these “extra” teeth that only seem to cause pain and discomfort? The answer is simple: diet. Only in the past few centuries have humans been able to keep all their teeth. Before advancements in the field of dentistry and hygiene, wisdom teeth fit into mouths, since other teeth had already been lost.

Previously, our diet mainly consisted of meat, leaves and branches. So, our jaws were also bigger than what we have today and allowed all the teeth to fit in properly. As humans became more civilized, we started practicing hygiene and eating properly. This paved the way for small jaws but apparently, our wisdom teeth never received the memo. This is why most of us have to make a visit to the dentists office at least once in our lifetime to get rid of them. They are now considered a vestigial feature of the human body. (source)

6. The palmar grasp reflex was used by ancestral primate babies to grasp onto their parents for transport. It is still present in babies today and can be simply tested by placing your finger on an infant’s palm (or feet!). You will see that they will try to grasp it immediately.

The palmar grasp reflex is a characteristic behavior of human infants and can be seen as early as 16 weeks old. If you carefully place your finger in the infants palm, you can see that they will grab onto your finger immediately. This reaction is natural and is known as palmar grasp reflex. Studies show that an average infant is capable of holding their own weight for at least 10 seconds when hanging by their hands from a horizontal rod (Do not try this at home).

The same reflex is found in monkey infants, which possess a similar involuntary grasping behavior. However, they are capable of hanging from one hand for more than half an hour. This reflex is essential for primates, since their survival is dependent on their mother and they move from one place to another by clinging on to the mother’s body fur. In human infants, the reflex typically disappears within a period of six months. (source)

7. In the sixth week of gestation, the human embryo possesses a tail, complete with several vertebrae. Within the next few weeks, the tail disappears, and over time the vertebrae fuse to form the coccyx, or tailbone.

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Image: DBCLS

The tailbone is a remnant of the tail possessed by our primate ancestors. Although we no longer require it, our ancestors used it for balancing. Today, they are still present in month old embryos and there are over 100 recorded cases of babies born with them. Also called the coccyx, the tailbone is not actually a bone; rather four bones fused together. Located at the bottom of the spine, they serve little purpose. However, it serves as an attachment site for tendons, ligaments, and muscles. (source)

8. The reason why we push others away when we are tickled is because of a defensive reflex that is designed to protect our vital organs.

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Image: Gabrielle Henderson

According to scientists at the University of Tuebingen, Germany, tickling activates the part of our brain that anticipates pain; which explains why we lash out at someone when they are tickling us. Furthermore, it is part of a defense mechanism that dates back to man’s earliest evolution and developing self-awareness. If you think of it, our tickle spots are also our weak spots, such as our neck or our stomach. According to researchers, back in the day, parents tickled their offspring to train them to react to danger and that the laughter of tickling is an acknowledgement of defeat. (source)

9. Many people are known to faint at the sight of blood, which is an evolutionary trait. Since fainting for such reasons was a big no-no back in our violent early days, our ancestors were used to the scene. However, as we became more civilized, our bodies trigger the process of fainting to reroute the resources to keep the brain alive.

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Image: Christopher Burns

The brain is one of the most vital parts of the human body. We know it and so does our brain. When in distress, our body ensures that all resources are routed towards our vital organs to keep us alive. Fainting is such a mechanism. In ancient times, our ancestors were always battling for food, land and what not. So, seeing blood was nothing new for them. However, as we became more civilized, such scenes were seen lesser. When we see blood or anything distressing, some people immediately faint. This is known as vasovagal syncope.

During this process, our body purposely deactivates itself so we lay in a horizontal position. This allows blood to flow back to your brain at a faster rate since there’s less gravitational pull. In animals such as giraffes, only 1% of blood is required to keep the brain working while humans require about 20%. So basically, vasovagal syncope is a safety mechanism to ensure our survival. (source)

10. Researchers believe that the reason we have hiccups is because of our amphibian ancestors.

hiccups, life, body, evolution, facts, people, science
Image: rawpixel

Referred to in medicine as singultus, it is defined by a sudden contraction of the diaphragm and intercostal muscles, followed by snapping shut of the glottis. The characteristic sound and bodily jerk is caused by the quick spasm of inhalation colliding with the closed larynx. Researchers believe that this happens due to the fact that our ancient ancestors had gills to help them breathe.

This latest theory, originally published in the journal BioEssays and reported in New Scientist magazine, explains that hiccups do serve a purpose. Most creatures push water across their gills by squeezing their mouth cavity while closing the glottis, in order to stop water from getting into their lungs. Scientists now have reason to believe that the characteristic persisted into modern mammals, including humans. (source)

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