Question

What are the vestigial organs? Write two names of vestigial organs found in man.

Answer 1

Hint: Vestigial organs are the organs which have no specific function and are considered as residual parts which are acquired from the past ancestors. These types of organs or structure can arise due to the gene mutation which can be due to the change in proteins.

Complete answer:
Vestigial organs are the tissues or organs that are no more functional that way they were in their ancestral form of the trait. The occurrence of such structures increases if they get benefits. The non-functioning organ regenerates itself eventually and disappears ultimately by shrinking its size. These organs represent functions which were out of necessity now for survival. That function became nonexistent. In humans, an appendix is a vestigial organ. Snakes have pelvic bone which shows vestigiality in snakes. The birds which cannot fly consist of wings which are vestigial to them. Some vestigial organs found in man are appendix and coccyx. The appendix is the vestigial organ which is most common in the human body. It is present at the vermiform which is a finger like a tube closed at one end. It is believed to have brought about the digestion of cellulose in the ancestors. Scientists believe that it helps in digestion by bacteria nowadays. The coccyx is the last part of the vertebral column which is the residue of the lost tail. It is commonly known as tailbone and observed in humans during embryogenesis.

Additional Information: Vestigiality should be governed by drawing the similarities concerning their homologous features. Vestigial organs can be pointless to favourable based on their selection. Some of the vestigial organs degenerate over some time due to less or no utility to avoid the consequences of selective pressures or genetic drift.
Examples of vestigial organs found in man are:
Sinuses: Human cheekbones consists of the maxillary sinuses which are air pockets of the face. Their outer layer is a thin layer of mucosa and it has no significant use but its infection can lead to sinusitis.
Wisdom tooth: It is the third set of molars in our buccal cavity which have significance in the past for chewing rough and raw food. It is remote and inaccessible nowadays and can cause pain and infection.
External ear: The outer rim of the ear which is known as the helix is a vestigial structure which is the underdeveloped muscle in the ear and is unable to bring about the movement of ears.
Nictitating membrane: Nictitating membrane is the third eyelid that is found in few animals which protect the eyes and keep them most which helps them in vision. It is replaced by plica semilunaris in humans.
Tonsils: Tonsils are the vestigial organs in the human body which act as the first line of defence and protect the body from harmful microorganisms which are inhaled or ingested by the body.

Note: Vestigial organs serve as the evidence for evolution which can make sense if evolution has occurred. Male breast tissues and nipples are considered as useless limbs in the human body. Hymen in human females are considered vestigial by some scientists as it covers the vagina and protects it from infection from the embryonic stage till the time they first mate. Hymen present in horses, chimps and elephants exist after they prevent the leaking of semen from the vagina.