It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
After age 30, the brain shrinks a quarter of a percent (0.25%) in mass each year.
139
It has been scientifically proven that stroking a cat can lower one's blood pressure!
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The largest cell in the human body is the female egg and the smallest is the male sperm.
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A person can live without food for about a month, but only about a week without water.
156
The average sperm cell swims at 8 inches per hour.
4
When you are looking at someone you love, your pupils dilate, they do the same when you are looking at someone you hate.
1k
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
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