Pet dogs and elephants are the only animals that seem to instinctively understand human gesture.
14
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
It takes about 20 seconds for a red blood cell to circle the whole body.
102
Poor eyesight (myopia) is associated with higher IQ.
232
Enamel is hardest substance in the human body.
61
It took 200,000 years for humans to reach 3 billion in number. It took 40 years for the next 3 billion.
11
On average a woman has 4 sexual partners in her lifetime.
-143
Tigers can see 6 times better at night than humans.
305