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
The human body contains over a billion miles of DNA.
147
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
If your DNA was stretched out it would reach to the moon 6,000 times.
256
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
Chewing gum boosts your brain power.
285