For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Every year your body replaces 98% of your atoms.
119
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
One human hair can support 3 ounces.
191
The average sperm cell swims at 8 inches per hour.
76
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
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18