Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Enamel is hardest substance in the human body.
61
Your thumb is about the same size as your nose.
124
One human hair can support 3 ounces.
191
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
Yawns are more contagious among people with closer relationships.
163
Every year your body replaces 98% of your atoms.
119