In 2011, archaeologists discovered the skeletal remains of a Roman couple who have been holding hands for 1,500 years.
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The focusing muscles of the eyes move around 100,000 times a day. To give your leg muscles the same workout, you would need to walk 80km (50 miles) every day.
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Cows can sleep standing up, but they can only dream lying down.
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The oldest glowing lightbulb was first switched on in 1901 and lives in fire stations in Livermore, CA. It is known as the Centennial Light.
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Only about 2% of the world population has green eyes.
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