For something that is literally a part of us, there's a lot about our bodies that we don't know. Check out these surprising facts about our strange and awesome bodies:
1. The sound you hear when you "crack your knuckles" is actually gas popping. Small bubbles form in your joints and pop when you torque them, and no this doesn't cause arthritis.
2. What's the weird way to spot an intelligent man? Look for body hair. A study of men in MENSA (a club for people with high IQs) found that hairier men were also smarter, and men with back and chest hair were the smartest of all.
4. There are some proportions that all human bodies seem to share. Here's one: take the height of your head and multiply it by 7. That's about the size of your body (most people are somewhere between 7 and 7.5 heads tall).
5. Know anyone who never seems to blush? It's a physical reaction caused by your emotions, so some people never seem too. In fact babies, who have no sense of adult emotions and feelings, actually can't blush.
6. Here's another weird proportion: stretch your arms to the side. This measurement (called the wingspan) is usually very close to your height.
7. When you sneeze, air is pushed out of your nose and mouth at 100 miles per hour, shooting mucus as far as 30 feet. For comparison, wind only needs to blow at 74 miles per hour to qualify as a hurricane.
Pop quiz: how many bones are in your body? Actually, it depends on your age...