Early American humans hunted car-size armadillos and used their shells for houses.
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Yawns are more contagious among people with closer relationships.
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It has been scientifically proven that stroking a cat can lower one's blood pressure!
456
In one day, adult lungs move about 10,000 litres of air.
11
The average sperm cell swims at 8 inches per hour.
4
Your heart will pump about 212 million liters in its lifetime.
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It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
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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.
21