Yawns are more contagious among people with closer relationships.
163
When you take a step, you are using up to 200 muscles.
886
Enamel is hardest substance in the human body.
61
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
It takes about 20 seconds for a red blood cell to circle the whole body.
102
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
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118