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Today, the list of human vestigial structures is still the same, although the list of useless 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 Plica Semilunaris , the small fold of tissue on the inside corner of the eye, is the vestigial remnant of the Nictitating Membrane (the Third Eyelid ) in other animals. The formation of Goosebumps in humans under 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, although it was also used to trap an insulating layer of warm air next to the skin. Some traits may be vestigial in one Sex but not another because they are Homologous but do not share similar functions between the sexes. Organs with a distinct purpose in one sex, for example the Nipple , may be more or less useless in the other, but not harmful enough to be selected against. These become vestigial traits in one sex. The Clitoris has been described as a vestigial Penis by some scientists, such as Stephen Jay Gould . In Whale s and other Cetacean s, one can find small vestigial leg bones deeply buried within the body; these are remnants of their land-living ancestors' legs. The wings of Ostrich es and Emu s are vestigial, remnants of their flying ancestors' wings. Some debate occurs regarding the definition for "vestigial," with some claiming a strict interpretation that an organ must be utterly useless to classify. Others claim that an organ in a modern animal may be described as vestigial if it does not serve the same function in the modern animal as the Cognate organ served in an ancestor, even if the modern organ Serves A Completely Different Use . An example of the dispute is the Gas Bladder of many fish, which is thought to be a vestigial Lung , "left over" from the occasionally-air-gasping common ancestor of Ray-finned Fish and land vertebrates. Because vestigial organs can be used as supporting evidence for Evolution , some Creationists oppose the idea. SEE ALSO
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