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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.
Cytomegalovirus affects nearly the same amount of newborns every year as Down syndrome.
It is believed that the Incas used anesthesia. Evidence supports the theory that shamans chewed cocoa leaves and drilled holes into the heads of patients (letting evil spirits escape), spitting into the wounds they made. The mixture of cocaine, saliva, and resin numbed the site enough to allow hours of drilling.
Adult head lice are gray, about ? inch long, and often have a tiny dot on their backs. A female can lay between 50 and 150 eggs within the several weeks that she is alive. They feed on human blood.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.