It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
Blue eyes are a genetic mutation. Before the mutation occured, all humans had brown eyes.
89
Unconsciousness will occur after 8-10 seconds after loss of blood supply to the brain.
93
Women have about four times as many foot problems as men; lifelong patterns of wearing high heels often are the culprit.
111
You can't tickle yourself.
29
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 world's shortest man measures only 21.5 inches.
73
After age 30, the brain shrinks a quarter of a percent (0.25%) in mass each year.
139