Enamel is hardest substance in the human body.
61
Women have about four times as many foot problems as men; lifelong patterns of wearing high heels often are the culprit.
111
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
Yawns are more contagious among people with closer relationships.
163
If every muscle in your body could pull in one direction, you could lift nearly 25 tons.
22
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18