The focusing muscles of the eyes move around 100,000 times a day. To give your leg muscles the same workout, you would need to walk 80km (50 miles) every day.
21
The human brain doesn't stop developing until about 25 years old.
102
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99
The average person's skin weighs twice as much as their brain.
131
There are glasses which allow a red-green color-blind person to see colors the way everyone else does.
22
One human hair can support 3 ounces.
191
In 30 minutes, the average body gives off enough heat (combined) to bring a half gallon of water to boil.
199
Some monks can increase their body temperature so much they can dry soaking sheets in a freezing room!
32