Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
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
Your heart will pump about 212 million liters in its lifetime.
26
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
The average sperm cell swims at 8 inches per hour.
76