Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
One human hair can support 3 ounces.
191
Your body is creating and killing about 2.4 million red blood cells per second.
17
The human brain doesn't stop developing until about 25 years old.
102
It takes about 20 seconds for a red blood cell to circle the whole body.
102
If your DNA was stretched out it would reach to the moon 6,000 times.
256
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
When you take a step, you are using up to 200 muscles.
886