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There are 60,000 miles of blood vessels in every adult human.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
Stroke kills people from all ethnic backgrounds, but the people at highest risk for fatal strokes are: black men, black women, Asian men, white men, and white women.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
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.