For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
If you hold farts in during the day, they'll just come out when you sleep.
16
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
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
You can hear the blood flowing through your ears if you find a quiet place and cover them tightly.
19
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
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118