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Vaccines prevent between 2.5 and 4 million deaths every year.
If all the neurons in the human body were lined up, they would stretch more than 600 miles.
Cancer has been around as long as humankind, but only in the second half of the twentieth century did the number of cancer cases explode.
About 600,000 particles of skin are shed every hour by each human. If you live to age 70 years, you have shed 105 pounds of dead skin.
There are 60,000 miles of blood vessels in every adult human.
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