Blue eyes are a genetic mutation. Before the mutation occured, all humans had brown eyes.
89
Our brains have a negativity bias and will remember bad memories more than good ones.
15
In one day, adult lungs move about 10,000 litres of air.
11
The human brain doesn't stop developing until about 25 years old.
102
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
Enamel is hardest substance in the human body.
61
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
Early American humans hunted car-size armadillos and used their shells for houses.
12