Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Your thumb is about the same size as your nose.
124
The largest cell in the human body is the female egg and the smallest is the male sperm.
682
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
When you get goosebumps and your hair stands, the hair helps to trap air, making you feel warmer by keeping in your body heat.
46
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
Yawns are more contagious among people with closer relationships.
163
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197