Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
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
When you get goosebumps and your hair stands, the hair helps to trap air, making you feel warmer by keeping in your body heat.
46
The human body contains over a billion miles of DNA.
147
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217