Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
One human hair can support 3 ounces.
191
The human brain doesn't stop developing until about 25 years old.
102
Every year your body replaces 98% of your atoms.
119
The human brain uses approximately as much energy as a 10 watt light bulb.
120
The human body contains over a billion miles of DNA.
147
Dogs can be trained to identify the scent of lung cancer long before symptoms develop.
190
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55