Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Enamel is hardest substance in the human body.
61
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
The human brain uses approximately as much energy as a 10 watt light bulb.
120
If every muscle in your body could pull in one direction, you could lift nearly 25 tons.
22
Poor eyesight (myopia) is associated with higher IQ.
232