Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
Yawns are more contagious among people with closer relationships.
163
The average sperm cell swims at 8 inches per hour.
76
The average person's skin weighs twice as much as their brain.
131
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Most of us have microscopic, worm like mites named Demodex that live in our eyelashes and have claws and a mouth.
-137
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515