Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
When you take a step, you are using up to 200 muscles.
886
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
Women have about four times as many foot problems as men; lifelong patterns of wearing high heels often are the culprit.
111
It would take about 1,200,000 mosquitoes to fully drain the average human body of blood.
217