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
Your thumb is about the same size as your nose.
124
Every year your body replaces 98% of your atoms.
119
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
The human body contains over a billion miles of DNA.
147
Chewing gum boosts your brain power.
285