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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You can only remember 4 things at a time.
31
Approximately one-third of the population can't snap their fingers!
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The world's youngest parents were 8 and 9 and lived in China in 1910.
130
The average person walks the equivalent of twice around the world in a lifetime
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Blonde hair is not exclusive to Europeans. Melanesians of the south Pacific evolved a different gene for blonde hair.
7