For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The average sperm cell swims at 8 inches per hour.
76
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
One human hair can support 3 ounces.
191
Women have about four times as many foot problems as men; lifelong patterns of wearing high heels often are the culprit.
111
Your thumb is about the same size as your nose.
124
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127