Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Poor eyesight (myopia) is associated with higher IQ.
232
Quick naps not only improve your alertness, but they also help in decision making, creativity and sensory perception.
149
One human hair can support 3 ounces.
191
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
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 brain uses approximately as much energy as a 10 watt light bulb.
120
Yawns are more contagious among people with closer relationships.
163