All humans have the ability to see ultraviolet light, but it is passively filtered out by the eye's lens. People who undergo surgery to remove the lens can detect ultraviolet light.
22
Your body is creating and killing about 2.4 million red blood cells per second.
17
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
There are glasses which allow a red-green color-blind person to see colors the way everyone else does.
22
If you hold farts in during the day, they'll just come out when you sleep.
16
You can hear the blood flowing through your ears if you find a quiet place and cover them tightly.
19
The levels of two stress hormones, cortisol and epinephrine which suppress the body's immune system, will actually drop after a dose of laughter.
112
Your heart will pump about 212 million liters in its lifetime.
26