Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
One human hair can support 3 ounces.
191
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
The human brain doesn't stop developing until about 25 years old.
102
Poor eyesight (myopia) is associated with higher IQ.
232
If every muscle in your body could pull in one direction, you could lift nearly 25 tons.
22