It takes about 20 seconds for a red blood cell to circle the whole body.
102
Early American humans hunted car-size armadillos and used their shells for houses.
12
The human brain uses approximately as much energy as a 10 watt light bulb.
120
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
On average, there's 100 billion neurons in the human brain.
83
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13