Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
When you get goosebumps and your hair stands, the hair helps to trap air, making you feel warmer by keeping in your body heat.
46
Oxygen, carbon, hydrogen and nitrogen make up 90% of the human body.
118
The human body contains over a billion miles of DNA.
147
The human brain doesn't stop developing until about 25 years old.
102
The average person's skin weighs twice as much as their brain.
131