The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
Mars had an oxygen-rich atmosphere around 4 billion years ago
13
The strangers in your dreams are actually people that you've seen in real life.
50
Cows can sleep standing up, but they can only dream lying down.
745
No one knows Albert Einstein's last words. Just before he passed, he spoke several words in German, but his nurse only knew English.
154