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Vestigial Organs

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Evolution is a natural process. It is a continuous process of development. Evolution sometimes develops new traits in the creature. Sometimes Evolution stops developing any organ or traits. What will happen in the Evolution process, none can predict. Evolution can develop Homologous Structure. Also, Evolution is responsible for developing Analogous Structures. Along with these two types of structure, Evolution process some unique traits in the creature. These traits are witnesses of the Evolution process among the creature. Vestigial Organs are among those traits developed by the Evolution Process.

What are Vestigial Organs?

Vestigial Organs are such parts of the body or cell of the body that stops working due to the process of Evolution, but they still exist in the modern creature. This means some organs in the human body are no longer needed by the modern human species. But still, they are present the in the body. These organs were helpful for their ancestral species. But they are not usable for the new species. Not only humans, but many species possess Vestigial Organs.

Any organ which is not developed with the Evolution process can act as the Vestigial Organ. In normal conditions, Evolution developed organs to the better or modern versions of the existing ones. But due to some exceptions, if the organ is not being developed in a great manner, then the organ is showing the symptoms to be a Vestigial Organ.

Evolutionary Background Of Vestigial Organs

Evolution is a continuous process. Evolution is only controlled by the Natural Selection process. Nature controls which organism needs to be developed in a certain creature. Also, besides that, there should be strong willpower of the creature to survive in nature. The combination of both these two can create a new species. In this way, Evolution works.

But sometimes, due to some exceptions, we see the opposite of the above process. In such cases, some organs stop developing themselves. As there is no further need to develop. Due to the Natural Selection process, a creature tends to develop a new trait. That trait is suppressing the existing mechanism in the creature. The existing mechanism in the creature may be old enough to survive in nature.

In such cases, creatures develop new traits in themselves. And they started neglecting the existing mechanism or organ. In this way, those organs become inactive over time. After millions of years, those organs become Vestigial Organs. As degradation of any organ also takes a long time.

Importance Of Vestigial Organs

Though there is not any usage of Vestigial Organ in any species. Many years ago, creatures stop using those organs in their daily life. But still, they have importance. The importance is from the view of the Evolution process. By viewing the Vestigial Organs, scientists believe that there is Evolutionary similarity among many species. Along with the Homologous Structure & Analogous Structure, Vestigial Organs play an important role to find out the missing links among species.

Some scientists believe that there are some similarities between the Homologous Structure & Vestigial Organ. As both of them pretends that species are developed from a single ancestor. Some Vestigial Organs are common in many species. Some Vestigial Organs are working organs for many species. Scientists draw some relationships among those species by studying the Vestigial Organ.

Vestigial Organs


Example of Vestigial Organs In Humans

  1. Eye Membrane: They are usually known as the Nictitating Membrane. This is the third eye membrane found in many small creatures. This membrane helps to moisturize the eyes. But humans don’t need any such third eye membrane more. So, that is why it is replaced with the Plica semilunaris. So, this is an example of a Vestigial Organ in a Human.
  2. Appendix: It is one of the well-known Vestigial Organs in humans. It is a finger-like tube associated with the Large Intestine. Scientists believe that it is necessary for the ancestors of humans. That time they tend to eat raw vegetables. That time Appendix helps to digest those raw foods. The Bacteria which lived in the Appendix help to digest that. But when humans discovered the fire & start cooking the food from that time humans used Appendix relatively less. In this way, the Appendix becomes the Vestigial Organ.
  3. Sinuses Bones: They are usually known as the Sinuses. They are bones located behind the forehead of humans. They are air-filled bones. Generally, they don’t have any uses. Scientists believe that they are Vestigial Organs. But sometimes due to bacterial infection, Sinus diseases may arise.
  4. Coccyx Bone: It is the tailbone of humans. Ancestor humans possess a tail. But with time, they stop using their tail. That is why the tail becomes the Vestigial Organ. In the newborn baby, Coccyx may be in active form. But with time, nearly within two or three months, it reacts as the Vestigial Organ there.
  5. Wisdom Tooth: This is the third set of molars found in humans. Sometimes, in humans, Wisdom Teeth can be found. Mostly, this can be found in children. Scientists believe that this tooth was important when the human ancestor used to take raw food. They use this tooth to intake raw & solid food. This tooth helps them to chew the food in a good manner.
  6. External Ear: The External Ear in humans is a Vestigial Organ. Earlier, ancestors of humans can move their ears toward the source of the soundwave, like Cats & Dogs. But with time, the muscles in the External Ear or Helix are not developed well. That is why it is considered the Vestigial Organ. As we can’t use the muscles there at present.
  7. Tonsil: The tonsil is the little muscular projection found in the mouth of humans. This is also a type of Vestigial Organ. As this piece of muscle doesn’t have any specific function to perform. It is just like the Appendix in the human body. It just acts to project Bacteria incur to the human body through the nose & mouth.
  8. Behavioral: Though there are not any Vestigial Organs present that can be categorized into the Behavioral type. But Goosebumps is a kind of Vestigial Movement. It is not the Organ. So, scientists have classified Goosebumps as the Behavioral Vestigial. Scientists believe that ancestors of humans had the ability to raise body hairs with emotions. Just like the Cat, arises their body hair with anger. Such ability was there in ancestors of humans. But with time, the ability to rise the body hair is lost. That is why humans now can’t able to rise their body hair. Only we can visualize the Goosebumps as the Behavioral Vestigial.

Vestigial Organs In Other Animals

  1. Legs In Snake: Scientists believe that snakes evolved from lizards. But they don’t have legs. But in some species of snakes there is evidence that at some point in time, they have legs. In Boa & Python, they have Rear Leg like structure in their body. The leg act as the vestigial organ in those species.
  2. Eyes Of Salamander: Salamanders have eyes. But they don’t use them. As they live in the cave most of the time. Scientists believe that due to the immense low use of the eyes, those become the Vestigial Organ for the Salamander.
  3. Teeth Of Whale Shark: Whale Shark is a type of shark. They used to feed with the Gill. They use the Gill as the filter & incur the food to its body. But still, they have teeth. Though, those teeth can’t do their work. This means they are the Vestigial Organ of Whale Sharks.
  4. Wings Of Flightless Bird: Cormorant is a type of bird. There are many Cormorant species in the world. Among them, one is the Galapagos Cormorants. This type of bird has wings. But they can use them. As they can’t able to fly. Scientists believe they have evolved in such a way nearly 2 million years ago. Also, the flightless birds have wings as the Vestigial Organ. Ostrich belongs to the same category. They also have wings, but they can’t use them to fly.

FAQs on Vestigial Organs

Question 1: Are nails the Vestigial Organs in the human body?


No, nails are not the Vestigial Organs in humans. They are serving their task. They are used to protect the fingertips from any type of injury. Also, it helps to hold anything with a great grip. So, nails can’t consider the Vestigial Organ.

Question 2: Are body hair a Vestigial organ in the human body?


No, body hair is not a Vestigial Organ in humans. Though, they do have not fixed tasks to perform in our life. Not having any task to perform doesn’t mean that the organ is a Vestigial Organ. Still, the Body Hair responded with reflexes & emotions. So they still respond with stimulus. 

Question 3: Why we don’t need the third eye membrane to moisturize our eyes?


Humans developed a special gland near the eyes. The upper eyelids help to moisturize the human eyeballs. Every movement of the upper eyelids, moisture the human eyeballs. That is why there is no need to have a third eyelid in humans. That is why it becomes the Vestigial Organ & replaced with Plica semilunaris.

Question 4: Are eyelids in human Vestigial Organs?


A human has a total of three eyelids. Among them, two are functional. They are the upper eyelid & lower eyelid. They are still in function. Only the third eyelid is not functional in humans. They are the Vestigial Organ. So, only one eyelid becomes the Vestigial Organ.

Question 5: Are ear muscles a Vestigial Organ?


Yes, ear muscles are a Vestigial Organ. Other creatures can move their ear toward the source of the sound with the help of ear muscles. But humans stop using those muscles for a long time. Since not using those muscles, they became the Vestigial Organ for humans.

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Last Updated : 13 Sep, 2022
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