10 Useless Body Parts

1. Nipples on men
Nipples appear on men because all embryos effectively start out as "female." The Y chromosome and testosterone are what make an embryo male. But nipples form before the testosterone comes into play, so the nipples remain.   

2. Appendix

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.

3. 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 made them just a huge pain.

4. Arrector pili

When we were hairier (see No. 9), the arrector pili made the hairs stand on end when we needed to appear bigger and scarier. Now, it just gives us goose bumps.

5. Coccyx

More useful as a game-winning Scrabble word than as part of the anatomy, the coccyx, or tailbone, is made up of several fused vertebrae left over from the olden days when we had tails.

6. Tonsils

Also prone to swelling and infection. If you still have them when you reach your 30s, it's almost an accomplishment.

7. Adenoids

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 ...

8. Sinuses

Doctors don't really know much about sinuses -- only that we have a lot of them. Possibilities for their function range from insulating our eyes to changing the pitch and tone of our voice.

9. Body hair

No doubt we were once hairier. Up until about 3 million years ago, we were covered with body hair. But by the time Homo erectus arrived, the ability to sweat meant we could shed our woolly ways.

10. Plica semilunaris

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. This small third eyelid is left over from what's known as a "nictitating membrane," which is still present in full form in some animals including chickens, lizards and sharks.