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Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
The average office desk has 400 times more bacteria on it than a toilet.
As the western states of America were settled, pioneers often had to drink rancid water from ponds and other sources. This often resulted in chronic diarrhea, causing many cases of dehydration and death that could have been avoided if clean water had been available.
The familiar sounds of your heart are made by the heart's valves as they open and close.
About one in five American adults and teenagers have had a genital herpes infection—and most of them don't know it. People with genital herpes have at least twice the risk of becoming infected with HIV if exposed to it than those people who do not have genital herpes.