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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.
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).
The heart is located in the center of the chest, with part of it tipped slightly so that it taps against the left side of the chest.
Parkinson's disease is both chronic and progressive. This means that it persists over a long period of time and that its symptoms grow worse over time.
Adolescents often feel clumsy during puberty because during this time of development, their hands and feet grow faster than their arms and legs do. The body is therefore out of proportion. One out of five adolescents actually experiences growing pains during this period.