Vestigial organs are those structures in some organisms which have no apparent function in their bodies but once they were functioning. They are considered a residual part of a past ancestor. In case of snakes, for example, they possess pelvic bones but they do not have legs so these non-functional pelvic bones are vestigial structures. Like many other organisms, there are a few Vestigial organs in humans.
Vestigial structures are considered an evidence for evolution by many scientists. Charles Darwin pointed out such structures in humans and other organisms as an evidence for evolution.
Vestigial Organs in Humans
As in many other organisms, humans also have vestigial organs. There are many examples of vestigial organs in humans. A few of them are the vermiform appendix, tailbone, erector pili muscles and wisdom teeth etc.
The appendix in humans is a small pouch attached to the large intestine. It apparently has no function and those who have removed it never seem to miss it.
Human embryo possesses a tail in the sixth week of gestation with many vertebrae. But in the following weeks, these vertebrae fuse to form the coccyx or tailbone in the adult.
The shift in human diet towards soft and processed food over time caused a reduction in the number of powerful grinding teeth, especially the third molars or wisdom teeth, which were highly prone to impaction.
Erector Pili Muscles
Goosebumps causing muscles, erector pili muscles, are not only to alert you of cold. They had a different function in ancestors (e.g. bear) to make them look bigger and scarier to the attacking organisms.
Nipples in the male are also considered vestigial structures. But, men have nipples early in the gestation, which in adult males have no apparent function.