You can't tickle yourself.
29
Shark corneas are used in eye transplants and shark bone marrow can be used to graft human bones.
132
Pet dogs and elephants are the only animals that seem to instinctively understand human gesture.
14
It takes about 20 seconds for a red blood cell to circle the whole body.
102
When you are looking at someone you love, your pupils dilate, they do the same when you are looking at someone you hate.
1k
It takes twice as long to lose new muscle if you stop working out than it did to gain it.
127
The oldest stone tools found are dated from 2.7 - 2.9 million years ago. The species that made these tools is unknown.
13
The largest cell in the human body is the female egg and the smallest is the male sperm.
682