Only 12,000 years ago there was a species closely related to modern humans called Homo floresiensis that had been living on an Indonesian Island. They used fire and rather advanced tools, yet were only about 3 feet tall and weighed around 25kg.
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The human eye blinks an average of 4,200,000 times a year.
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Every human spent about half an hour as a single cell.
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Tigers can see 6 times better at night than humans.
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It takes approximately 12 hours for food to entirely digest.
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For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
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The average sperm cell swims at 8 inches per hour.
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You can't tickle yourself.
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