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Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
Alzheimer's disease affects only about 10% of people older than 65 years of age. Most forms of decreased mental function and dementia are caused by disuse (letting the mind get lazy).
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).
A cataract is a clouding of the eyes' natural lens. As we age, some clouding of the lens may occur. The first sign of a cataract is usually blurry vision. Although glasses and other visual aids may at first help a person with cataracts, surgery may become inevitable. Cataract surgery is very successful in restoring vision, and it is the most frequently performed surgery in the United States.
Egg cells are about the size of a grain of sand. They are formed inside of a female's ovaries before she is even born.