It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
If the human eye was a digital camera, it would have 576 megapixels.
25
Crying literally alleviates stress and uniquely allows humans to decrease feelings of anger and sadness.
24
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13
Shark corneas are used in eye transplants and shark bone marrow can be used to graft human bones.
132
The human brain is more active during sleep than during the day.
28
The largest cell in the human body is the female egg and the smallest is the male sperm.
682
A person can live without food for about a month, but only about a week without water.
156