It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
After age 30, the brain shrinks a quarter of a percent (0.25%) in mass each year.
139
Due to the angle at which the optic nerve enters the brain, staring at a blue surface during sex greatly increases the intensity of orgasms.
252
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
The average sperm cell swims at 8 inches per hour.
4
Every human spent about half an hour as a single cell.
144
On average, there's 100 billion neurons in the human brain.
83