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Only 12 hours after an egg cell is fertilized by a sperm cell, the egg cell starts to divide. As it continues to divide, it moves along the fallopian tube toward the uterus at about 1 inch per day.
The average human gut is home to perhaps 500 to 1,000 different species of bacteria.
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.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.
Approximately 500,000 babies are born each year in the United States to teenage mothers.