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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.
The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."
Signs and symptoms of a drug overdose include losing consciousness, fever or sweating, breathing problems, abnormal pulse, and changes in skin color.
In most cases, kidneys can recover from almost complete loss of function, such as in acute kidney (renal) failure.
Vaccines prevent between 2.5 and 4 million deaths every year.