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Fewer than 10% of babies are born on their exact due dates, 50% are born within 1 week of the due date, and 90% are born within 2 weeks of the date.
The first documented use of surgical anesthesia in the United States was in Connecticut in 1844.
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.
Blood is approximately twice as thick as water because of the cells and other components found in it.
There are over 65,000 known species of protozoa. About 10,000 species are parasitic.