Vestigial organ

A vestigial organ is an organ whose original function has been lost during evolution.

In 1893, Robert Wiedersheim published a list of 86 human organs that had no known function. Theorizing that they were vestiges of evolution, he called them "vestigial".

Today, the list of human vestigial organs is much smaller, and hotly debated. It still includes the appendix, and coccyx. Many people maintain that the coccyx is a remnant of a lost tail. Wisdom teeth are vestigial as well. The formation of goose bumps in humans under emotional stress is a vestigial reflex; its purpose in our evolutionary ancestors was to raise hair to make the animal appear bigger and scare off enemies.

Some traits may be vestigial in one gender] but not another because they are homologous but do not share similar functions between the genders. Organs with a distinct purpose in one gender, for example the nipple, may be more or less useless in the other, but not harmful enough to be selected against. These become vesitigial traits in one gender. Some scientists believe that the clitoris is a vestigial penis found in the female.

In whales and other cetaceans, one can find small vestigial leg bones deeply buried within the body; these are remnants of their land-living ancestors' legs. The wings of ostriches and emus are vestigial, remnants of their flying ancestors' wings.

Because they are good evidence for evolution, creationists have vigorously attacked the idea of vestigial organs, and often claim that for an organ to be vestigial it must be utterly useless. This is a misrepresentation: an organ now useful for one function, that was once used for a different function which it can no longer fulfill, is vestigial.