The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
There are glasses which allow a red-green color-blind person to see colors the way everyone else does.
22
A human brain produces as many as 12,000 to 50,000 thoughts per day, depending on how deep a thinker a person is.
23
On average, a human being will have sex more than 3,000 times and spend two weeks kissing in their lifetime.
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Research has determined that most people are happiest at 7:26pm on a Saturday night.
69
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.
73
There are times when you're walking that the pressure on your feet exceeds your body weight, and when you're running, it can be three or four times your weight.
62
Only humans shed emotional tears.
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