Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Yawns are more contagious among people with closer relationships.
163
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
Your thumb is about the same size as your nose.
124
The human body contains over a billion miles of DNA.
147