Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
Every year your body replaces 98% of your atoms.
119
For most people, no matter how hard you pinch the skin on your elbow with your fingers it doesn't hurt.
515
If you are cold you are more likely to be hungry because you use energy to keep warm.
143
Poor eyesight (myopia) is associated with higher IQ.
232
Your heart will pump about 212 million liters in its lifetime.
26
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
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55