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When Gabriel Fahrenheit invented the first mercury thermometer, he called "zero degrees" the lowest temperature he was able to attain with a mixture of ice and salt. For the upper point of his scale, he used 96°, which he measured as normal human body temperature (we know it to be 98.6° today because of more accurate thermometers).
Between 1999 and 2012, American adults with high total cholesterol decreased from 18.3% to 12.9%
There are 20 feet of blood vessels in each square inch of human skin.
Vaccines prevent between 2.5 and 4 million deaths every year.
Vampire bats have a natural anticoagulant in their saliva that permits continuous bleeding after they painlessly open a wound with their incisors. This capillary blood does not cause any significant blood loss to their victims.