Only humans shed emotional tears.
331
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
Enamel is hardest substance in the human body.
61
There are glasses which allow a red-green color-blind person to see colors the way everyone else does.
22
In 30 minutes, the average body gives off enough heat (combined) to bring a half gallon of water to boil.
198
Poor eyesight (myopia) is associated with higher IQ.
232
When you are looking at someone you love, your pupils dilate, they do the same when you are looking at someone you hate.
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