It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
Some monks can increase their body temperature so much they can dry soaking sheets in a freezing room!
31
A man's beard grows fastest when he anticipates sex.
239
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
Shark corneas are used in eye transplants and shark bone marrow can be used to graft human bones.
132
On average, there's 100 billion neurons in the human brain.
83