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In the ancient and medieval periods, dysentery killed about ? of all babies before they reach 12 months of age. The disease was transferred through contaminated drinking water, because there was no way to adequately dispose of sewage, which contaminated the water.
The immune system needs 9.5 hours of sleep in total darkness to recharge completely.
The modern decimal position system was the invention of the Hindus (around 800 AD), involving the placing of numerals to indicate their value (units, tens, hundreds, and so on).
Each year in the United States, there are approximately six million pregnancies. This means that at any one time, about 4% of women in the United States are pregnant.
More than 2,500 barbiturates have been synthesized. At the height of their popularity, about 50 were marketed for human use.