Every day thousands of people get their wisdom teeth and appendices removed, and suffer from inflamed tonsils. Someone may consider all these body parts completely useless, but they have a clear purpose.
Why would a man need nipples? The answer may seem surprising, but in the womb, all babies develop the same at first. Later, boys acquire male secondary sex characteristics. So men’s and women’s nipples are the same, but without the influence of the female hormone estrogen it is just an “ornament”.
There are two types of sweat glands – eccrine and apocrine ones. Apocrine glands are located under the arms, and you need those to send sexual signals for finding partners. Underarm hair is needed for the smell (even not too pleasant for most people) to last as long as possible.
The evolutionary origin of eyebrows is not exactly established. Perhaps they are needed to retain sweat and raindrops for eye protection. There is a theory about using them to express emotions or other similar communication signals, as well as for gaining individual personality traits. People without eyebrows are recognized worse, as studies have shown.
This is a vestigial organ, which means that it has lost much of its original features in the course of the evolution. Previously, it served people who ate mostly raw, uncooked food as a tool for fermentation. There is a theory that this organ is a habitat to healthy bacteria.
Theoretically it is part of the lymphatic system, necessary for our immunity. Lymph nodes are important, but they are a bit excessive, so the removal of the tonsils causes no damage to health.
You need to use jaw bones, as well as other parts of the body, constantly for them to grow properly. However, people eat more and more soft, cooked food, and the jaw does not grow to its potential size. Wisdom teeth are another vestige, which is formed after all the other teeth.
It takes years for the boy foreskin to move away from the glans. It is easy to assume that nature intended it to prevent infections in children, especially little ones.