Enamel is hardest substance in the human body.
61
A third of the human population sneezes when they look at the Sun. Light can signal the ocular nerve near the sinuses and triggers a sneeze.
18
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
Early American humans hunted car-size armadillos and used their shells for houses.
12
The average person will go on a date at least 100 times before they finally marry.
33
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Poor eyesight (myopia) is associated with higher IQ.
232
On average, there's 100 billion neurons in the human brain.
83