Our current form is the result of millions of years of evolution and during the process we have greatly reduced or completely omitted certain activities to bend to the demands of the environment; and as we evolved so did our organ system plus certain body features; it signified, if it was reduction (in size), the end of certain activity or character so that an organism could “perfectly” survive in its habitat. Some remnants of a once fully functional organ or body feature do exist in human beings, some of the vestiges are:
They can sprout up when there is no space often growing sideways impacting other molars, it can affect mastication (chewing) because of the pain and discomfort. A surgery is necessary in such a case. Chewing is not hindered in any way in the absence of wisdom tooth.
These third molars were present in our ancestors who had larger jaws and teeth which provided more efficiency in proper grinding of foliage pre-digestion as plant cells have cell walls made of cellulose. Evolution favored smaller jaws as diet changed later yet the wisdom tooth still continued to develop in humans today. Currently they are of no apparent use though some people do chew with wisdom teeth personal records however note that there were no complications chewing after removal.
There are muscles in the ear that our ancestors utilised to move their ear separately from the head, it was necessary to pick up sound and signals to be alert to imminent threats. It was a necessary tool for survival. It serves no purpose in a civilized and social group like ours today except as an entertainment for people who love to watch others wiggle their ears.
The vermiform appendix is a tubular structure attached to the large intestine. It is 2-20 cm long. In ancestral form the appendix assumed the role of digesting cellulose from plants efficiently for energy. Later when food became more easily digestible the appendix shrunk and loss its original function.
They are not vital for survival but it has been experimentally shown that the appendix has lymphoid cells suggesting that it might play a role in immune system. It also acts as a safe-house for symbiotic bacteria (that aids in digestion) so that when a gastrointestinal disorder occurs (such as diarrhea) and cleans everything out, the appendix being a pouch-like structure at the beginning of the large intestine remains untouched, the bacteria there then starts multiplying and restoring normal gut condition.
The last bone on the spine is a remnant of an actual tail. Every mammal had one during the course of evolution or at least during embryonic development. In humans for 31–35 days the tail remains prominent which is at stages 14-22 of embryogenesis. There have been cases of babies being born with small tail-like structure.
The coccyx is an attachment point for muscles, which explains why it has not disappeared although we lost our tail when ancestors started walking upright and no longer needed to dwell on branches.
Our goose bumps are brought about by these small muscle fibers. It helped retain and insulate heat in our hairy ancestors.
There’s not enough hair in our body for this to work; get a sweater!
Eye lashes do help in keeping the dust particles off the eye. People keep hairs on their heads and face to style their looks but besides these there’s no requirement that is necessary for survival; we use sweaters now for insulating heat.
So now you know that you can shave your legs during the next marathon.
These are embryonic remnants. Men and women both start out the same in the mother’s womb and start developing similar body features of any human being: legs, hands, nipples etc. When a Y chromosome is present the fetus produces androgen hormones and develops into male where nipples become of no use.