Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
The human body contains over a billion miles of DNA.
147
Your body is creating and killing about 2.4 million red blood cells per second.
17
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
73
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515