Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
The average sperm cell swims at 8 inches per hour.
76
Every year your body replaces 98% of your atoms.
119
The human brain doesn't stop developing until about 25 years old.
102
Stress can result in more headaches as a result of the body rerouting blood flow to other parts of the body.
92
Your heart will pump about 212 million liters in its lifetime.
26