Published October 14, 2011
| Discovery News
1. Plica Semilunaris (Third Eyelid)
You may not know it, but you have a third eyelid. Pull open the two more noticeable eyelids and take a look - it's located right in the corner by the tear duct.
The third eyelid is left over from what's known as a "nictitating membrane," which is still present in animals like chickens, lizards and sharks.
2. Body Hair
No doubt we were once hairier. Up until about 3 million years ago, we were covered with it. But by the time Homo erectus arrived, the ability to sweat meant we could shed our wooly ways
Adenoids trap bacteria, but they're also prone to swelling and infection. Just ask any 7-year-old. Luckily, our adenoids shrink with age and are often removed, along with ..
Also prone to swelling and infection. If you have them by your 30s, it's almost an accomplishment.
More useful as a game-winning Scrabble word than part of the anatomy, the coccyx, or tailbone, is several fused vertebrae left over from the olden days when we had tails.
6. Erector Pili
When we were hairier, the erector pili made the hairs stand on end when we needed to appear bigger and scarier. Now, it just gives us goose bumps.
7. Wisdom Teeth
Back in the day, when we ate mammoth meat off the bone and didn't floss afterward, our teeth tended to fall out. Therefore, when those reserve molars, aka "wisdom teeth," came in they were welcomed. Nowadays, fluoride and dental plans have just made them a huge pain.
Darwin claimed the appendix was useful for digestion during our early plant-eating years; it's dwindled down to little since we started eating more digestible foods.
9. Male Nipples
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