Enamel is hardest substance in the human body.
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After age 30, the brain shrinks a quarter of a percent (0.25%) in mass each year.
139
Every human spent about half an hour as a single cell.
144
On average, a human being will have sex more than 3,000 times and spend two weeks kissing in their lifetime.
161
The world's shortest man measures only 21.5 inches.
73
The human body contains over a billion miles of DNA.
147
Poor eyesight (myopia) is associated with higher IQ.
232
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13