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
The world's shortest man measures only 21.5 inches.
73
Having sex can make a woman look younger and more attractive due to the release of estrogen and collagen.
346
By weight, Bone is five times stronger than steel.
417
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 adult human brain weighs about 3 pounds (1,300-1,400 g).
99
Every human spent about half an hour as a single cell.
144