Bacteria have flourished on the earth for over three billion years. They were the first life forms on the planet.
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Patients who cannot swallow may receive nutrition via a parenteral route—usually, a catheter is inserted through the chest into a large vein going into the heart.
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There are approximately 3 million unintended pregnancies in the United States each year.
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Vaccines prevent between 2.5 and 4 million deaths every year.
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The average adult has about 21 square feet of skin.
Transitional forms between dinosaurs and birds
These two desert arthropods, a scorpion and a cicada, have evolved very different approaches to livi