The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
One human hair can support 3 ounces.
191
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
It takes about 20 seconds for a red blood cell to circle the whole body.
102
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The human body contains over a billion miles of DNA.
147