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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Rio de Janeiro was once capital of Portugal, making it the only European capital outside of Europe.
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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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Scientists in Germany have developed a candy that doesn't cause cavities.
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Dogs can make about 100 different facial expressions.
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Disney's first choice to play Jack Sparrow was Jim Carrey.
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