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There are over 65,000 known species of protozoa. About 10,000 species are parasitic.
In 1844, Charles Goodyear obtained the first patent for a rubber condom.
The tallest man ever known was Robert Wadlow, an American, who reached the height of 8 feet 11 inches. He died at age 26 years from an infection caused by the immense weight of his body (491 pounds) and the stress on his leg bones and muscles.
Your skin wrinkles if you stay in the bathtub a long time because the outermost layer of skin (which consists of dead keratin) swells when it absorbs water. It is tightly attached to the skin below it, so it compensates for the increased area by wrinkling. This happens to the hands and feet because they have the thickest layer of dead keratin cells.
About 3% of all pregnant women will give birth to twins, which is an increase in rate of nearly 60% since the early 1980s.