Enamel is hardest substance in the human body.
61
The human brain doesn't stop developing until about 25 years old.
102
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
An Indian man known as "Snake Manu" can put small snakes, including deadly cobras, into his mouth and pass them out through his nose.
59
Cracking your knuckles does not actually hurt your bones or cause arthritis. The sound you hear is just gas bubbles bursting.
18
The human body contains over a billion miles of DNA.
147
After age 30, the brain begins to lose about 50,000 neurons per day - shrinking the brain .25% each year.
55