In 2011, archaeologists discovered the skeletal remains of a Roman couple who have been holding hands for 1,500 years.
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A cow produces around 200,000 glasses of milk in her lifetime.
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The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
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Pet dogs and elephants are the only animals that seem to instinctively understand human gesture.
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