Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Stress can result in more headaches as a result of the body rerouting blood flow to other parts of the body.
92
The human brain doesn't stop developing until about 25 years old.
102
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
The human body contains over a billion miles of DNA.
147
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
Your body is creating and killing about 2.4 million red blood cells per second.
17