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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The offspring of two sets of identical twins are legally cousins but genetically siblings.
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According to the American Society for Microbiology, 90% of women and 75% of men wash their hands after using a public restroom.
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Blonde hair is not exclusive to Europeans. Melanesians of the south Pacific evolved a different gene for blonde hair.
7
Awarding people money for doing well in IQ tests causes them to score better, $10 increased people's score by an average of more than 20 IQ points. IQ tests don’t just measure intelligence - they also measure effort.
9
Most people turn their music down in the car when finding a street sign to "see better".
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