Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55
The human brain is very soft, having a consistency similar to soft gelatin or firm tofu.
13
Your heart will pump about 212 million liters in its lifetime.
26
Every year your body replaces 98% of your atoms.
119
When you take a step, you are using up to 200 muscles.
886
Your thumb is about the same size as your nose.
124
Coughing can cause air to move through your windpipe faster than the speed of sound - over a thousand feet per second!
197