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The familiar sounds of your heart are made by the heart's valves as they open and close.
It is believed that humans initially contracted crabs from gorillas about 3 million years ago from either sleeping in gorilla nests or eating the apes.
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).
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
There are more sensory neurons in the tongue than in any other part of the body.