The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The average sperm cell swims at 8 inches per hour.
76
Every year your body replaces 98% of your atoms.
119
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
Yawns are more contagious among people with closer relationships.
163
Poor eyesight (myopia) is associated with higher IQ.
232