Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
The average person's skin weighs twice as much as their brain.
131
There are times when you're walking that the pressure on your feet exceeds your body weight, and when you're running, it can be three or four times your weight.
62
When you take a step, you are using up to 200 muscles.
885
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13
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