Enamel is hardest substance in the human body.
61
Yawns are more contagious among people with closer relationships.
163
Chewing gum boosts your brain power.
285
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Poor eyesight (myopia) is associated with higher IQ.
232
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55