Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
Your body is creating and killing about 2.4 million red blood cells per second.
17
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Your heart will pump about 212 million liters in its lifetime.
26
It takes about 20 seconds for a red blood cell to circle the whole body.
102
The average person's skin weighs twice as much as their brain.
131
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515