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
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
Every year your body replaces 98% of your atoms.
119
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
Our Right Lungs takes more air than our left lung.
194