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Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
Most childhood vaccines are 90–99% effective in preventing disease. Side effects are rarely serious.
Hippocrates noted that blood separates into four differently colored liquids when removed from the body and examined: a pure red liquid mixed with white liquid material with a yellow-colored froth at the top and a black substance that settles underneath; he named these the four humors (for blood, phlegm, yellow bile, and black bile).
There are more nerve cells in one human brain than there are stars in the Milky Way.
The U.S. Preventive Services Task Force recommends that all women age 65 years of age or older should be screened with bone densitometry.