The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
Only about 2% of the world population has green eyes.
36
A lump of pure gold the size of a matchbox can be flattened into a sheet the size of a tennis court.
140
An unprotected human can survive up to 1.5 minutes in space with no permanent bodily damage.
82
In 2011, archaeologists discovered the skeletal remains of a Roman couple who have been holding hands for 1,500 years.
81
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
The strangers in your dreams are actually people that you've seen in real life.
50