Enamel is hardest substance in the human body.
61
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
73
Your thumb is about the same size as your nose.
124
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
The human brain doesn't stop developing until about 25 years old.
102
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515