Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
An average heart beats 100,000 times a day, pumping some 2,000 gallons of blood through its chambers. Over a 70-year life span, that adds up to more than 2.5 billion heartbeats.
73
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197
The human body contains over a billion miles of DNA.
147
The human brain uses approximately as much energy as a 10 watt light bulb.
120
Poor eyesight (myopia) is associated with higher IQ.
232
Chewing gum boosts your brain power.
285
If you are cold you are more likely to be hungry because you use energy to keep warm.
143