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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Only about 2% of the world population has green eyes.
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Your body is creating and killing about 2.4 million red blood cells per second.
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It's possible to die from a broken heart; it's called Stress Cardiomyopathy.
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In 2011, archaeologists discovered the skeletal remains of a Roman couple who have been holding hands for 1,500 years.
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