Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
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
Your thumb is about the same size as your nose.
124
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
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
Poor eyesight (myopia) is associated with higher IQ.
232