It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
Due to the angle at which the optic nerve enters the brain, staring at a blue surface during sex greatly increases the intensity of orgasms.
252
Enamel is hardest substance in the human body.
61
Modern humans first appeared about 200,000 years ago, but record keeping didn't begin until about 6,000 years ago. That means about 97% of human history is lost.
21
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
Gorillas can catch human colds and other illnesses.
205
Fingers prune underwater not because of them absorbing the water or washing away the oil, but because of an evolutionary trait caused by the brain to enhance the grip of your fingers underwater.
24
It has been scientifically proven that stroking a cat can lower one's blood pressure!
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