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Asthma cases in Americans are about 75% higher today than they were in 1980.
The familiar sounds of your heart are made by the heart's valves as they open and close.
In 1844, Charles Goodyear obtained the first patent for a rubber condom.
Although the Roman numeral for the number 4 has always been taught to have been "IV," according to historians, the ancient Romans probably used "IIII" most of the time. This is partially backed up by the fact that early grandfather clocks displayed IIII for the number 4 instead of IV. Early clockmakers apparently thought that the IIII balanced out the VIII (used for the number 8) on the clock face and that it just looked better.
Sperm cells are so tiny that 400 to 500 million (400,000,000–500,000,000) of them fit onto 1 tsp.