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
When you take a step, you are using up to 200 muscles.
886
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
Your heart will pump about 212 million liters in its lifetime.
26
Every year your body replaces 98% of your atoms.
119
The adult human brain weighs about 3 pounds (1,300-1,400 g).
99