Yawns are more contagious among people with closer relationships.
163
Enamel is hardest substance in the human body.
61
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
Your thumb is about the same size as your nose.
124
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The human brain doesn't stop developing until about 25 years old.
102
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
When you take a step, you are using up to 200 muscles.
886