Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
One human hair can support 3 ounces.
191
If you are cold you are more likely to be hungry because you use energy to keep warm.
144
The average sperm cell swims at 8 inches per hour.
76
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
If every muscle in your body could pull in one direction, you could lift nearly 25 tons.
22
The human brain doesn't stop developing until about 25 years old.
102