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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).
Approximately 500,000 babies are born each year in the United States to teenage mothers.
Blood in the urine can be a sign of a kidney stone, glomerulonephritis, or other kidney problems.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
Although puberty usually occurs in the early teenage years, the world's youngest parents were two Chinese children who had their first baby when they were 8 and 9 years of age.