Enamel is hardest substance in the human body.
61
In 30 minutes, the average body gives off enough heat (combined) to bring a half gallon of water to boil.
198
The human brain doesn't stop developing until about 25 years old.
102
On average, there's 100 billion neurons in the human brain.
83
Blue eyes are a genetic mutation. Before the mutation occured, all humans had brown eyes.
89
You can't tickle yourself.
29