Enamel is hardest substance in the human body.
61
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
It takes about 20 seconds for a red blood cell to circle the whole body.
102
There are times when you're walking that the pressure on your feet exceeds your body weight, and when you're running, it can be three or four times your weight.
62
One human hair can support 3 ounces.
191
The human brain uses approximately as much energy as a 10 watt light bulb.
120
Poor eyesight (myopia) is associated with higher IQ.
232
The human brain doesn't stop developing until about 25 years old.
102