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
Enamel is hardest substance in the human body.
61
Humans are capable of running 40 mph according to a study by bio-mechanical expert Dr. Matthew Bundle. Today's fastest man, Usain Bolt, has a top speed of 28 mph.
34
It takes approximately 12 hours for food to entirely digest.
93
Every human spent about half an hour as a single cell.
144
A person can live without food for about a month, but only about a week without water.
156
There are glasses which allow a red-green color-blind person to see colors the way everyone else does.
22