Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
Your heart will pump about 212 million liters in its lifetime.
26
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
Yawns are more contagious among people with closer relationships.
163
The average sperm cell swims at 8 inches per hour.
76