Blue eyes are a genetic mutation. Before the mutation occured, all humans had brown eyes.
89
It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
Modern humans first appeared about 200,000 years ago, but record keeping didn't begin until about 6,000 years ago. That means about 97% of human history is lost.
21
In one day, adult lungs move about 10,000 litres of air.
11
You can't tickle yourself.
29
Your heart will pump about 212 million liters in its lifetime.
26
A person will create enough saliva to fill two average size swimming pools during his lifetime.
191
Every human spent about half an hour as a single cell.
144