Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Stress can result in more headaches as a result of the body rerouting blood flow to other parts of the body.
92
Yawns are more contagious among people with closer relationships.
163
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217
Your heart will pump about 212 million liters in its lifetime.
26