On average, there's 100 billion neurons in the human brain.
83
After age 30, the brain shrinks a quarter of a percent (0.25%) in mass each year.
139
An unprotected human can survive up to 1.5 minutes in space with no permanent bodily damage.
82
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
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
Research has determined that most people are happiest at 7:26pm on a Saturday night.
69
Early American humans hunted car-size armadillos and used their shells for houses.
12
Blue eyes are a genetic mutation. Before the mutation occured, all humans had brown eyes.
89