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
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
Stress can result in more headaches as a result of the body rerouting blood flow to other parts of the body.
92
The human brain doesn't stop developing until about 25 years old.
102
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13
Yawns are more contagious among people with closer relationships.
163