Blue eyes are a genetic mutation. Before the mutation occured, all humans had brown eyes.
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An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
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You can hear the blood flowing through your ears if you find a quiet place and cover them tightly.
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You see your nose at all times, your brain just chooses to ignore it.
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Your heart will pump about 212 million liters in its lifetime.
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