Enamel is hardest substance in the human body.
61
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
The average person's skin weighs twice as much as their brain.
131
One human hair can support 3 ounces.
191
Staying awake for 17 hours is the same for your body as drinking 2 glasses of wine.
193
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
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