Yawns are more contagious among people with closer relationships.
163
The average person's skin weighs twice as much as their brain.
131
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
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
It takes about 20 seconds for a red blood cell to circle the whole body.
102
When you take a step, you are using up to 200 muscles.
886
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515