Early American humans hunted car-size armadillos and used their shells for houses.
12
After age 30, the brain shrinks a quarter of a percent (0.25%) in mass each year.
139
It takes approximately 12 hours for food to entirely digest.
93
If Earth's life was compressed into 1 year, then humans would have been around for only 2 seconds.
15
An unprotected human can survive up to 1.5 minutes in space with no permanent bodily damage.
82
If the human eye was a digital camera, it would have 576 megapixels.
25
It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
The average sperm cell swims at 8 inches per hour.
4