1. Vestigial Organ: Undeveloped Eyes on Blind Mole Rats

The blind mole rat (Spalax typhlus) has tiny eyes completely covered by a layer of skin. The blind mole rat is completely blind and is unable to see any light. Blind mole rats spend most of their time digging about ½ foot to 2 feet underground, looking for roots and underground vegetation to eat.

Their eyes begin to form as they develop, but a layer of skin grows over them and their lenses and corneas do not form correctly. Scientists have determined that the cells in the eyes of

these blind mole rats could still respond to light, but no light reaches them in their current location, underneath skin and fur. 2. Vestigial Organ: Human Appendix

Humans have a small part on the end of their intestines called an appendix. Many modern species have a similar organ, which is used to digest cellulose and other materials from plants. The human appendix has lost this function and we are no longer able to digest those substances. Some carnivorous animals may have appendices too. Because these species do not rely on these plant materials to

survive, we do not need to digest them to survive.

Research suggests that the appendix may still have some use. It could guard against the loss of bacteria that aid in digestion. Intestinal bacteria in the appendix may support quick replacement of the healthy bacteria after an illness, poisoning, or antibiotic treatment depletes them in the colon.

3. Vestigial Structure: Wings on Ostriches

Ostriches have small wings, but do not fly. Wings are complex structures specifically

suited for flight, but ostriches cannot use their wings to fly.

Even though they can’t fly, they can still have some use for their wings. When they're running, they use their wings for balance, extending them to the sides to keep from toppling over. They also use their wings in mating displays, and spread them out to shade their chicks from the harsh African sun.

Scientists have learned from studying ostrich DNA that they are related to birds that can fly, but ostriches use their speed and size to avoid predators and no longer need flight to survive.4. Vestigial Structure: Undeveloped Hind Legs on Baleen Whales

Many species of whales have small leg bones buried deep within the back of the body. Whales do not use the bones as fins, legs, or any other functional part. In the baleen whale above, the bones marked “C” indicate small undeveloped hind leg bones.

In creatures that walk on their legs, these structures often have many small bones and joints to allow for movement. In whales like the one above, the bones are fused together and do not move. These are not fins. They are located entirely inside of the body of the whale and cannot be used for movement.

5. Vestigial Structure: Muscles around the Human Ear

Humans have muscles around the ears that have no function. Some humans are able to wiggle their ears slightly, but they cannot move their ears enough to serve any function.

Many mammals (like the one above) have far more developed muscles than those of humans, and therefore have the capability to move their ears to better hear potential threats.

In humans, the ability to move the ear is not necessary because they may turn the head from side to side, an ability that not all animals have. A function once provided by one structure is now replaced by another.6. Vestigial Behavior: “Goosebumps” reflex on Human Skin

A reflex in muscles of human skin can cause the condition commonly known as “goosebumps.” Small bumps show on human skin when people become excited, scared, or cold.

In many organisms, a similar reflex functions as a response to cold, heat, and stress. This behavior could cause the animal to look larger and more menacing by puffing out the hair. It could also keep the animal from getting cold.

However, because humans do not have a full coat of body hair, this reflex is useless.

7. Vestigial Gene: Human Enzyme for the Production of Vitamin C (L-gulonolactone oxidase)

Most plants and animals can produce their own vitamin C. Dogs, cats, yeast, reptiles, and birds all synthesize their own Vitamin C out of materials such as simple sugars. Humans, on the other hand, need to consume vitamin C from sources like orange juice, or else we could get a sickness called scurvy.

L-gulonolactone oxidase is a gene that is functional in most other mammals and produces an enzyme that is used to make Vitamin C. In humans and guinea pigs, a

mutation disabled the gene and made it unable to produce the enzyme. However, the remains of the gene are still present in human DNA as a vestigial genetic sequence.

8. Vestigial Structure: Human Tail Bone (Coccyx)

The coccyx, or tailbone, is the remnant of a lost tail. All mammals had a tail at one point in their development. In humans, it is present for a period of 4 weeks, during the time an embryo is developing. This tail is most visible in human embryos 31–35 days old.

The tailbone is located at the end of the spine, below the hip bones. It has lost its original function in assisting balance and mobility, but it still serves some other functions, such as being an attachment point for muscles, which explains why it has not disappeared entirely.