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With so many body parts, can we expect them all to be useful? LiveScience lists those that do bugger-all, like wisdom teeth and body hair. To wit:
- Wisdom teeth: Our jaws have gotten smaller, so wisdom teeth can't fit anymore. Plus dental hygiene keeps our teeth from falling out and making room for the bulky molars.
- Tailbone: When our ancestors no longer needed tails for balance, evolution turned them into fused vertebrae called a coccyx.
- Male nipples: All fetuses have nipples, before testosterone makes each baby male or female. Ergo men's useless nipples. Note that some men have even lactated or gotten breast cancer.
- Body hair and Erector Pili: Conflict and fear can activate muscle fibers called erector pili in many animals, making body hair stand on end. Great for scaring off enemies—not so useful for us.
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