Yawns are more contagious among people with closer relationships.
163
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
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
The average sperm cell swims at 8 inches per hour.
76
The human body contains over a billion miles of DNA.
147
One human hair can support 3 ounces.
191