Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
If every muscle in your body could pull in one direction, you could lift nearly 25 tons.
22
One human hair can support 3 ounces.
191
Poor eyesight (myopia) is associated with higher IQ.
232
Yawns are more contagious among people with closer relationships.
163
The human body contains over a billion miles of DNA.
147
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 largest cell in the human body is the female egg and the smallest is the male sperm.
682