Enamel is hardest substance in the human body.
61
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
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
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
73
The human body contains over a billion miles of DNA.
147
The average person's skin weighs twice as much as their brain.
131