Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
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
Enamel is hardest substance in the human body.
61
An Indian man known as "Snake Manu" can put small snakes, including deadly cobras, into his mouth and pass them out through his nose.
59
Your body is creating and killing about 2.4 million red blood cells per second.
17
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
The average sperm cell swims at 8 inches per hour.
76