It takes about 20 seconds for a red blood cell to circle the whole body.
102
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Your thumb is about the same size as your nose.
124
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
The human brain doesn't stop developing until about 25 years old.
102
Yawns are more contagious among people with closer relationships.
163
If every muscle in your body could pull in one direction, you could lift nearly 25 tons.
22
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266