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
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
Every year your body replaces 98% of your atoms.
119
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
If your DNA was stretched out it would reach to the moon 6,000 times.
256
The average sperm cell swims at 8 inches per hour.
76
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127