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More than 50% of American adults have oral herpes, which is commonly known as "cold sores" or "fever blisters." The herpes virus can be active on the skin surface without showing any signs or causing any symptoms.
The Babylonians wrote numbers in a system that used 60 as the base value rather than the number 10. They did not have a symbol for "zero."
Human stomach acid is strong enough to dissolve small pieces of metal such as razor blades or staples.
People who have myopia, or nearsightedness, are not able to see objects at a distance but only up close. It occurs when the cornea is either curved too steeply, the eye is too long, or both. This condition is progressive and worsens with time. More than 100 million people in the United States are nearsighted, but only 20% of those are born with the condition. Diet, eye exercise, drug therapy, and corrective lenses can all help manage nearsightedness.
There are 20 feet of blood vessels in each square inch of human skin.
![This pre-Anasazi community in Mesa Verde, Colorado, was carved into a cliff, making it nearly impreg](https://biology-forums.com/gallery/47/medium_6_15_08_15_11_36_37_22212666.jpeg)
![Dewey and the reformers attacked classes, such as this one, circa 1900, where students sat up straig](https://biology-forums.com/gallery/47/medium_376716_26_08_15_11_14_03_224292294.jpeg)