Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Your body is creating and killing about 2.4 million red blood cells per second.
17
Every year your body replaces 98% of your atoms.
119
Quick naps not only improve your alertness, but they also help in decision making, creativity and sensory perception.
149
Poor eyesight (myopia) is associated with higher IQ.
232
The average sperm cell swims at 8 inches per hour.
76
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
There are times when you're walking that the pressure on your feet exceeds your body weight, and when you're running, it can be three or four times your weight.
62