Enamel is hardest substance in the human body.
61
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
Your body is creating and killing about 2.4 million red blood cells per second.
17
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
Poor eyesight (myopia) is associated with higher IQ.
232
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
Chewing gum boosts your brain power.
285