It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
Pluto is smaller than Russia.
9
Researchers say that lining the toilet seat with paper is pretty much pointless
8
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
Iron weighs more after it rusts.
16
People who sleep late have more mental stamina and can outperform early risers.
33
The human brain is more active during sleep than during the day.
28