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Some human body parts serve no purpose despite once having a specific function among our ancestors.
The appendix, for example, is not an essential body part (though some research suggests it may act as storage for good bacteria). In some cases, the appendix gets inflamed or ruptures, which requires surgical removal of the organ.
Several other body parts used to be important for humans' survival, but they have since become useless. Some of them can be removed, and their absence does not lower people's quality of life.
Take a look at nine of the most useless body parts.
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Many years ago, the appendix may have helped people digest plants that were rich in cellulose, Gizmodo reported .
Plant-eating vertebrates still rely on their appendix to help process plants, but the organ is not part of the human digestive system.
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For animals with thick fur, arrector pili can help provide insulation. The fibers can also make animals look bigger a porcupine benefits from this phenomenon.
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Tailbones helped our ancestors with mobility and balance, but the tail shrank as humans learned to walk upright. The coccyx now serves no purpose in humans.
Human infants are rarely born with a vestigial tail, though it does happen, according to Britannica . Doctors can remove the tail through surgery without major issues.
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The auricular muscles help other mammals localize sound and express emotion, according to Britannica . Unlike humans, animals like cats have to move their ears to hear well.
Some humans can wiggle their ears, but that's the best we can do.
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According to Britannica , the pyramidalis muscle can help contract the linea alba, but this is not relevant to the function of one's abdominal muscles.
About 20% of humans do not have any pyramidalis muscles.
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According to Brittanica , the muscle likely helped early humans with their grip. Now, however, someone's grip strength is the same whether or not they have the muscle.
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Men can't lactate under natural circumstances, but a high level of prolactin, the hormone that helps produce milk, can create this effect. Lactation is a possible side effect of digoxin, a heart medication, Scientific American reported .
While many male mammals could lactate under extreme scenarios, only the Dayak fruit bat, found in Southeast Asia, lactates spontaneously, according to Scientific American.
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Birds, reptiles, and some mammals can pull these membranes across their eyes to keep them moist and free of debris.
Gizmodo reported that our plica semilunaris is a remnant of these membranes, though humans are unable to control the tissue.
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