Yawns are more contagious among people with closer relationships.
163
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Your heart will pump about 212 million liters in its lifetime.
26
Every year your body replaces 98% of your atoms.
119
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
The average person's skin weighs twice as much as their brain.
131