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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Modern humans first appeared about 200,000 years ago, but record keeping didn't begin until about 6,000 years ago. That means about 97% of human history is lost.
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Enamel is hardest substance in the human body.
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Women have about four times as many foot problems as men; lifelong patterns of wearing high heels often are the culprit.
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On average, there's 100 billion neurons in the human brain.
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Blue eyes are a genetic mutation. Before the mutation occured, all humans had brown eyes.
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Cats have a weak sense of taste. They have only 473 tastebuds, humans have 9,000.
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