It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
Our eyes are always the same size from birth, but our nose and ears never stop growing.
266
The human brain is more active during sleep than during the day.
28
Blue eyes are a genetic mutation. Before the mutation occured, all humans had brown eyes.
89
Only humans shed emotional tears.
331
We share 70% of our DNA with a slug.
218
A person can live without food for about a month, but only about a week without water.
156
A person will create enough saliva to fill two average size swimming pools during his lifetime.
191