A man's beard grows fastest when he anticipates sex.
239
An unprotected human can survive up to 1.5 minutes in space with no permanent bodily damage.
82
By weight, Bone is five times stronger than steel.
417
It takes approximately 12 hours for food to entirely digest.
93
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 human sigh acts as a physiological reset button.
23
Modern humans first appeared about 200,000 years ago, but record keeping didn't begin until about 6,000 years ago. That means about 97% of human history is lost.
21
Early American humans hunted car-size armadillos and used their shells for houses.
12