When you are looking at someone you love, your pupils dilate, they do the same when you are looking at someone you hate.
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Blue eyes are a genetic mutation. Before the mutation occured, all humans had brown eyes.
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Only humans shed emotional tears.
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Tigers can see 6 times better at night than humans.
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It is possible for you to survive even after the removal of the spleen, the stomach, one kidney, one lung, 75% of the liver, 80% of the intestines, and almost every organ from the pelvic and groin area.
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Early American humans hunted car-size armadillos and used their shells for houses.
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The human brain doesn't stop developing until about 25 years old.
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It takes about 20 seconds for a red blood cell to circle the whole body.
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