Your thumb is about the same size as your nose.
124
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Enamel is hardest substance in the human body.
61
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Quick naps not only improve your alertness, but they also help in decision making, creativity and sensory perception.
149
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
Your heart will pump about 212 million liters in its lifetime.
26