The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
Cows can sleep standing up, but they can only dream lying down.
745
Your body is creating and killing about 2.4 million red blood cells per second.
17
If you have 1 billion dollars and spend $1,000 every day, it would take you 2,740 years to go broke.
31
A lump of pure gold the size of a matchbox can be flattened into a sheet the size of a tennis court.
140
In the last 7 years, humanity has discovered 43 potentially habitable planets.
14
The focusing muscles of the eyes move around 100,000 times a day. To give your leg muscles the same workout, you would need to walk 80km (50 miles) every day.
21