The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
It takes about 20 seconds for a red blood cell to circle the whole body.
102
The human brain has the capacity to store everything that you experience.
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The human brain is more active during sleep than during the day.
28
On average, a human being will have sex more than 3,000 times and spend two weeks kissing in their lifetime.
161
Enamel is hardest substance in the human body.
61
Tigers can see 6 times better at night than humans.
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